layout/generic/nsFrame.cpp
author Matt Woodrow <mwoodrow@mozilla.com>
Thu, 08 Jun 2017 15:24:03 +1200
changeset 411052 a3eec11c6b37419b1a700b2873d5a66b0db1e62d
parent 410444 80abb5ca3b7364930ab3cf177dca8ffb4512dca6
child 411061 6a84d1b254338f398a9558b886c0ca31a94e7874
permissions -rw-r--r--
Bug 1359709 - Use the DOM-ordering parent frame when deciding if a frame combines its transform with ancestors. r=dbaron

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
// vim:cindent:ts=2:et:sw=2:
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/* base class of all rendering objects */

#include "nsFrame.h"

#include <stdarg.h>
#include <algorithm>

#include "gfx2DGlue.h"
#include "gfxUtils.h"
#include "mozilla/Attributes.h"
#include "mozilla/DebugOnly.h"
#include "mozilla/gfx/2D.h"
#include "mozilla/gfx/PathHelpers.h"
#include "mozilla/Sprintf.h"

#include "nsCOMPtr.h"
#include "nsFrameList.h"
#include "nsPlaceholderFrame.h"
#include "nsIContent.h"
#include "nsIContentInlines.h"
#include "nsContentUtils.h"
#include "nsCSSPseudoElements.h"
#include "nsIAtom.h"
#include "nsString.h"
#include "nsReadableUtils.h"
#include "nsStyleContext.h"
#include "nsTableWrapperFrame.h"
#include "nsView.h"
#include "nsViewManager.h"
#include "nsIScrollableFrame.h"
#include "nsPresContext.h"
#include "nsStyleConsts.h"
#include "nsIPresShell.h"
#include "mozilla/Logging.h"
#include "mozilla/Sprintf.h"
#include "nsFrameManager.h"
#include "nsLayoutUtils.h"
#include "LayoutLogging.h"
#include "mozilla/GeckoRestyleManager.h"
#include "mozilla/RestyleManager.h"
#include "mozilla/RestyleManagerInlines.h"

#include "nsIDOMNode.h"
#include "nsISelection.h"
#include "nsISelectionPrivate.h"
#include "nsFrameSelection.h"
#include "nsGkAtoms.h"
#include "nsCSSAnonBoxes.h"

#include "nsFrameTraversal.h"
#include "nsRange.h"
#include "nsITextControlFrame.h"
#include "nsNameSpaceManager.h"
#include "nsIPercentBSizeObserver.h"
#include "nsStyleStructInlines.h"
#include "FrameLayerBuilder.h"
#include "ImageLayers.h"

#include "nsBidiPresUtils.h"
#include "RubyUtils.h"
#include "nsAnimationManager.h"

// For triple-click pref
#include "imgIContainer.h"
#include "imgIRequest.h"
#include "nsError.h"
#include "nsContainerFrame.h"
#include "nsBoxLayoutState.h"
#include "nsBlockFrame.h"
#include "nsDisplayList.h"
#include "nsSVGIntegrationUtils.h"
#include "nsSVGEffects.h"
#include "nsChangeHint.h"
#include "nsDeckFrame.h"
#include "nsSubDocumentFrame.h"
#include "SVGTextFrame.h"

#include "gfxContext.h"
#include "nsRenderingContext.h"
#include "nsAbsoluteContainingBlock.h"
#include "StickyScrollContainer.h"
#include "nsFontInflationData.h"
#include "nsRegion.h"
#include "nsIFrameInlines.h"
#include "nsStyleChangeList.h"

#include "mozilla/AsyncEventDispatcher.h"
#include "mozilla/EffectCompositor.h"
#include "mozilla/EffectSet.h"
#include "mozilla/EventListenerManager.h"
#include "mozilla/EventStateManager.h"
#include "mozilla/EventStates.h"
#include "mozilla/Preferences.h"
#include "mozilla/LookAndFeel.h"
#include "mozilla/MouseEvents.h"
#include "mozilla/ServoStyleSet.h"
#include "mozilla/css/ImageLoader.h"
#include "mozilla/gfx/Tools.h"
#include "nsPrintfCString.h"
#include "ActiveLayerTracker.h"

#include "nsITheme.h"
#include "nsThemeConstants.h"

using namespace mozilla;
using namespace mozilla::css;
using namespace mozilla::dom;
using namespace mozilla::gfx;
using namespace mozilla::layers;
using namespace mozilla::layout;
typedef nsAbsoluteContainingBlock::AbsPosReflowFlags AbsPosReflowFlags;

const mozilla::LayoutFrameType nsIFrame::sLayoutFrameTypes[
#define FRAME_ID(...) 1 +
#define ABSTRACT_FRAME_ID(...)
#include "nsFrameIdList.h"
#undef FRAME_ID
#undef ABSTRACT_FRAME_ID
  0] = {
#define FRAME_ID(class_, type_, ...) mozilla::LayoutFrameType:: type_,
#define ABSTRACT_FRAME_ID(...)
#include "nsFrameIdList.h"
#undef FRAME_ID
#undef ABSTRACT_FRAME_ID
};

const nsIFrame::FrameClassBits nsIFrame::sFrameClassBits[
#define FRAME_ID(...) 1 +
#define ABSTRACT_FRAME_ID(...)
#include "nsFrameIdList.h"
#undef FRAME_ID
#undef ABSTRACT_FRAME_ID
  0] = {
#define Leaf eFrameClassBitsLeaf
#define NotLeaf eFrameClassBitsNone
#define DynamicLeaf eFrameClassBitsDynamicLeaf
#define FRAME_ID(class_, type_, leaf_, ...) leaf_,
#define ABSTRACT_FRAME_ID(...)
#include "nsFrameIdList.h"
#undef Leaf
#undef NotLeaf
#undef DynamicLeaf
#undef FRAME_ID
#undef ABSTRACT_FRAME_ID
};

// Struct containing cached metrics for box-wrapped frames.
struct nsBoxLayoutMetrics
{
  nsSize mPrefSize;
  nsSize mMinSize;
  nsSize mMaxSize;

  nsSize mBlockMinSize;
  nsSize mBlockPrefSize;
  nscoord mBlockAscent;

  nscoord mFlex;
  nscoord mAscent;

  nsSize mLastSize;
};

struct nsContentAndOffset
{
  nsIContent* mContent;
  int32_t mOffset;
};

// Some Misc #defines
#define SELECTION_DEBUG        0
#define FORCE_SELECTION_UPDATE 1
#define CALC_DEBUG             0

// This is faster than nsBidiPresUtils::IsFrameInParagraphDirection,
// because it uses the frame pointer passed in without drilling down to
// the leaf frame.
static bool
IsReversedDirectionFrame(nsIFrame* aFrame)
{
  FrameBidiData bidiData = aFrame->GetBidiData();
  return !IS_SAME_DIRECTION(bidiData.embeddingLevel, bidiData.baseLevel);
}

#include "nsILineIterator.h"

//non Hack prototypes
#if 0
static void RefreshContentFrames(nsPresContext* aPresContext, nsIContent * aStartContent, nsIContent * aEndContent);
#endif

#include "prenv.h"

NS_DECLARE_FRAME_PROPERTY_DELETABLE(BoxMetricsProperty, nsBoxLayoutMetrics)

static void
InitBoxMetrics(nsIFrame* aFrame, bool aClear)
{
  if (aClear) {
    aFrame->DeleteProperty(BoxMetricsProperty());
  }

  nsBoxLayoutMetrics* metrics = new nsBoxLayoutMetrics();
  aFrame->SetProperty(BoxMetricsProperty(), metrics);

  static_cast<nsFrame*>(aFrame)->nsFrame::MarkIntrinsicISizesDirty();
  metrics->mBlockAscent = 0;
  metrics->mLastSize.SizeTo(0, 0);
}

static bool
IsXULBoxWrapped(const nsIFrame* aFrame)
{
  return aFrame->GetParent() &&
         aFrame->GetParent()->IsXULBoxFrame() &&
         !aFrame->IsXULBoxFrame();
}

void
nsReflowStatus::UpdateTruncated(const ReflowInput& aReflowInput,
                                const ReflowOutput& aMetrics)
{
  const WritingMode containerWM = aMetrics.GetWritingMode();
  if (aReflowInput.GetWritingMode().IsOrthogonalTo(containerWM)) {
    // Orthogonal flows are always reflowed with an unconstrained dimension,
    // so should never end up truncated (see ReflowInput::Init()).
    mTruncated = false;
  } else if (aReflowInput.AvailableBSize() != NS_UNCONSTRAINEDSIZE &&
             aReflowInput.AvailableBSize() < aMetrics.BSize(containerWM) &&
             !aReflowInput.mFlags.mIsTopOfPage) {
    mTruncated = true;
  } else {
    mTruncated = false;
  }
}

// Formerly the nsIFrameDebug interface

#ifdef DEBUG
std::ostream& operator<<(std::ostream& aStream,
                         const nsReflowStatus& aStatus)
{
  char complete = 'Y';
  if (aStatus.IsIncomplete()) {
    complete = 'N';
  } else if (aStatus.IsOverflowIncomplete()) {
    complete = 'O';
  }

  char brk = 'N';
  if (aStatus.IsInlineBreakBefore()) {
    brk = 'B';
  } else if (aStatus.IsInlineBreakAfter()) {
    brk = 'A';
  }

  aStream << "["
          << "Complete=" << complete << ","
          << "NIF=" << (aStatus.NextInFlowNeedsReflow() ? 'Y' : 'N') << ","
          << "Truncated=" << (aStatus.IsTruncated() ? 'Y' : 'N') << ","
          << "Break=" << brk << ","
          << "FirstLetter=" << (aStatus.FirstLetterComplete() ? 'Y' : 'N')
          << "]";
  return aStream;
}

static bool gShowFrameBorders = false;

void nsFrame::ShowFrameBorders(bool aEnable)
{
  gShowFrameBorders = aEnable;
}

bool nsFrame::GetShowFrameBorders()
{
  return gShowFrameBorders;
}

static bool gShowEventTargetFrameBorder = false;

void nsFrame::ShowEventTargetFrameBorder(bool aEnable)
{
  gShowEventTargetFrameBorder = aEnable;
}

bool nsFrame::GetShowEventTargetFrameBorder()
{
  return gShowEventTargetFrameBorder;
}

/**
 * Note: the log module is created during library initialization which
 * means that you cannot perform logging before then.
 */
mozilla::LazyLogModule nsFrame::sFrameLogModule("frame");

static mozilla::LazyLogModule sStyleVerifyTreeLogModuleInfo("styleverifytree");

static uint32_t gStyleVerifyTreeEnable = 0x55;

bool
nsFrame::GetVerifyStyleTreeEnable()
{
  if (gStyleVerifyTreeEnable == 0x55) {
      gStyleVerifyTreeEnable = 0 != (int)((mozilla::LogModule*)sStyleVerifyTreeLogModuleInfo)->Level();
  }
  return gStyleVerifyTreeEnable;
}

void
nsFrame::SetVerifyStyleTreeEnable(bool aEnabled)
{
  gStyleVerifyTreeEnable = aEnabled;
}

#endif

NS_DECLARE_FRAME_PROPERTY_DELETABLE(AbsoluteContainingBlockProperty,
                                    nsAbsoluteContainingBlock)

bool
nsIFrame::HasAbsolutelyPositionedChildren() const {
  return IsAbsoluteContainer() && GetAbsoluteContainingBlock()->HasAbsoluteFrames();
}

nsAbsoluteContainingBlock*
nsIFrame::GetAbsoluteContainingBlock() const {
  NS_ASSERTION(IsAbsoluteContainer(), "The frame is not marked as an abspos container correctly");
  nsAbsoluteContainingBlock* absCB = GetProperty(AbsoluteContainingBlockProperty());
  NS_ASSERTION(absCB, "The frame is marked as an abspos container but doesn't have the property");
  return absCB;
}

void
nsIFrame::MarkAsAbsoluteContainingBlock()
{
  MOZ_ASSERT(GetStateBits() & NS_FRAME_CAN_HAVE_ABSPOS_CHILDREN);
  NS_ASSERTION(!GetProperty(AbsoluteContainingBlockProperty()),
               "Already has an abs-pos containing block property?");
  NS_ASSERTION(!HasAnyStateBits(NS_FRAME_HAS_ABSPOS_CHILDREN),
               "Already has NS_FRAME_HAS_ABSPOS_CHILDREN state bit?");
  AddStateBits(NS_FRAME_HAS_ABSPOS_CHILDREN);
  SetProperty(AbsoluteContainingBlockProperty(), new nsAbsoluteContainingBlock(GetAbsoluteListID()));
}

void
nsIFrame::MarkAsNotAbsoluteContainingBlock()
{
  NS_ASSERTION(!HasAbsolutelyPositionedChildren(), "Think of the children!");
  NS_ASSERTION(GetProperty(AbsoluteContainingBlockProperty()),
               "Should have an abs-pos containing block property");
  NS_ASSERTION(HasAnyStateBits(NS_FRAME_HAS_ABSPOS_CHILDREN),
               "Should have NS_FRAME_HAS_ABSPOS_CHILDREN state bit");
  MOZ_ASSERT(HasAnyStateBits(NS_FRAME_CAN_HAVE_ABSPOS_CHILDREN));
  RemoveStateBits(NS_FRAME_HAS_ABSPOS_CHILDREN);
  DeleteProperty(AbsoluteContainingBlockProperty());
}

bool
nsIFrame::CheckAndClearPaintedState()
{
  bool result = (GetStateBits() & NS_FRAME_PAINTED_THEBES);
  RemoveStateBits(NS_FRAME_PAINTED_THEBES);
  
  nsIFrame::ChildListIterator lists(this);
  for (; !lists.IsDone(); lists.Next()) {
    nsFrameList::Enumerator childFrames(lists.CurrentList());
    for (; !childFrames.AtEnd(); childFrames.Next()) {
      nsIFrame* child = childFrames.get();
      if (child->CheckAndClearPaintedState()) {
        result = true;
      }
    }
  }
  return result;
}

bool
nsIFrame::IsVisibleConsideringAncestors(uint32_t aFlags) const
{
  if (!StyleVisibility()->IsVisible()) {
    return false;
  }

  const nsIFrame* frame = this;
  while (frame) {
    nsView* view = frame->GetView();
    if (view && view->GetVisibility() == nsViewVisibility_kHide)
      return false;
    
    nsIFrame* parent = frame->GetParent();
    nsDeckFrame* deck = do_QueryFrame(parent);
    if (deck) {
      if (deck->GetSelectedBox() != frame)
        return false;
    }

    if (parent) {
      frame = parent;
    } else {
      parent = nsLayoutUtils::GetCrossDocParentFrame(frame);
      if (!parent)
        break;

      if ((aFlags & nsIFrame::VISIBILITY_CROSS_CHROME_CONTENT_BOUNDARY) == 0 &&
          parent->PresContext()->IsChrome() && !frame->PresContext()->IsChrome()) {
        break;
      }

      if (!parent->StyleVisibility()->IsVisible())
        return false;

      frame = parent;
    }
  }

  return true;
}

void
nsIFrame::FindCloserFrameForSelection(
                                 nsPoint aPoint,
                                 nsIFrame::FrameWithDistance* aCurrentBestFrame)
{
  if (nsLayoutUtils::PointIsCloserToRect(aPoint, mRect,
                                         aCurrentBestFrame->mXDistance,
                                         aCurrentBestFrame->mYDistance)) {
    aCurrentBestFrame->mFrame = this;
  }
}

void
nsIFrame::ContentStatesChanged(mozilla::EventStates aStates)
{
}

AutoWeakFrame::AutoWeakFrame(const WeakFrame& aOther)
  : mPrev(nullptr), mFrame(nullptr)
{
  Init(aOther.GetFrame());
}

void
AutoWeakFrame::Init(nsIFrame* aFrame)
{
  Clear(mFrame ? mFrame->PresContext()->GetPresShell() : nullptr);
  mFrame = aFrame;
  if (mFrame) {
    nsIPresShell* shell = mFrame->PresContext()->GetPresShell();
    NS_WARNING_ASSERTION(shell, "Null PresShell in AutoWeakFrame!");
    if (shell) {
      shell->AddAutoWeakFrame(this);
    } else {
      mFrame = nullptr;
    }
  }
}

void
WeakFrame::Init(nsIFrame* aFrame)
{
  Clear(mFrame ? mFrame->PresContext()->GetPresShell() : nullptr);
  mFrame = aFrame;
  if (mFrame) {
    nsIPresShell* shell = mFrame->PresContext()->GetPresShell();
    MOZ_ASSERT(shell, "Null PresShell in WeakFrame!");
    if (shell) {
      shell->AddWeakFrame(this);
    } else {
      mFrame = nullptr;
    }
  }
}

nsIFrame*
NS_NewEmptyFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
{
  return new (aPresShell) nsFrame(aContext);
}

nsFrame::nsFrame(nsStyleContext* aContext, ClassID aID)
  : nsBox(aID)
{
  MOZ_COUNT_CTOR(nsFrame);

  mStyleContext = aContext;
  mWritingMode = WritingMode(mStyleContext);
  mStyleContext->AddRef();
#ifdef DEBUG
  mStyleContext->FrameAddRef();
#endif
}

nsFrame::~nsFrame()
{
  MOZ_COUNT_DTOR(nsFrame);

  MOZ_ASSERT(GetVisibility() != Visibility::APPROXIMATELY_VISIBLE,
             "Visible nsFrame is being destroyed");

  NS_IF_RELEASE(mContent);
#ifdef DEBUG
  mStyleContext->FrameRelease();
#endif
  mStyleContext->Release();
}

NS_IMPL_FRAMEARENA_HELPERS(nsFrame)

// Dummy operator delete.  Will never be called, but must be defined
// to satisfy some C++ ABIs.
void
nsFrame::operator delete(void *, size_t)
{
  MOZ_CRASH("nsFrame::operator delete should never be called");
}

NS_QUERYFRAME_HEAD(nsFrame)
  NS_QUERYFRAME_ENTRY(nsIFrame)
NS_QUERYFRAME_TAIL_INHERITANCE_ROOT

/////////////////////////////////////////////////////////////////////////////
// nsIFrame

static bool
IsFontSizeInflationContainer(nsIFrame* aFrame,
                             const nsStyleDisplay* aStyleDisplay)
{
  /*
   * Font size inflation is built around the idea that we're inflating
   * the fonts for a pan-and-zoom UI so that when the user scales up a
   * block or other container to fill the width of the device, the fonts
   * will be readable.  To do this, we need to pick what counts as a
   * container.
   *
   * From a code perspective, the only hard requirement is that frames
   * that are line participants
   * (nsIFrame::IsFrameOfType(nsIFrame::eLineParticipant)) are never
   * containers, since line layout assumes that the inflation is
   * consistent within a line.
   *
   * This is not an imposition, since we obviously want a bunch of text
   * (possibly with inline elements) flowing within a block to count the
   * block (or higher) as its container.
   *
   * We also want form controls, including the text in the anonymous
   * content inside of them, to match each other and the text next to
   * them, so they and their anonymous content should also not be a
   * container.
   *
   * However, because we can't reliably compute sizes across XUL during
   * reflow, any XUL frame with a XUL parent is always a container.
   *
   * There are contexts where it would be nice if some blocks didn't
   * count as a container, so that, for example, an indented quotation
   * didn't end up with a smaller font size.  However, it's hard to
   * distinguish these situations where we really do want the indented
   * thing to count as a container, so we don't try, and blocks are
   * always containers.
   */

  // The root frame should always be an inflation container.
  if (!aFrame->GetParent()) {
    return true;
  }

  nsIContent *content = aFrame->GetContent();
  LayoutFrameType frameType = aFrame->Type();
  bool isInline = (aFrame->GetDisplay() == StyleDisplay::Inline ||
                   RubyUtils::IsRubyBox(frameType) ||
                   (aFrame->IsFloating() &&
                    frameType == LayoutFrameType::Letter) ||
                   // Given multiple frames for the same node, only the
                   // outer one should be considered a container.
                   // (Important, e.g., for nsSelectsAreaFrame.)
                   (aFrame->GetParent()->GetContent() == content) ||
                   (content && (content->IsAnyOfHTMLElements(nsGkAtoms::option,
                                                             nsGkAtoms::optgroup,
                                                             nsGkAtoms::select) ||
                                content->IsInNativeAnonymousSubtree()))) &&
                  !(aFrame->IsXULBoxFrame() && aFrame->GetParent()->IsXULBoxFrame());
  NS_ASSERTION(!aFrame->IsFrameOfType(nsIFrame::eLineParticipant) ||
               isInline ||
               // br frames and mathml frames report being line
               // participants even when their position or display is
               // set
               aFrame->IsBrFrame() ||
               aFrame->IsFrameOfType(nsIFrame::eMathML),
               "line participants must not be containers");
  NS_ASSERTION(!aFrame->IsBulletFrame() || isInline,
               "bullets should not be containers");
  return !isInline;
}

void
nsFrame::Init(nsIContent*       aContent,
              nsContainerFrame* aParent,
              nsIFrame*         aPrevInFlow)
{
  MOZ_ASSERT(nsQueryFrame::FrameIID(mClass) == GetFrameId());
  NS_PRECONDITION(!mContent, "Double-initing a frame?");
  NS_ASSERTION(IsFrameOfType(eDEBUGAllFrames) &&
               !IsFrameOfType(eDEBUGNoFrames),
               "IsFrameOfType implementation that doesn't call base class");

  mContent = aContent;
  mParent = aParent;

  if (aContent) {
    NS_ADDREF(aContent);
  }

  if (aPrevInFlow) {
    mWritingMode = aPrevInFlow->GetWritingMode();

    // Make sure the general flags bits are the same
    nsFrameState state = aPrevInFlow->GetStateBits();

    // Make bits that are currently off (see constructor) the same:
    mState |= state & (NS_FRAME_INDEPENDENT_SELECTION |
                       NS_FRAME_PART_OF_IBSPLIT |
                       NS_FRAME_MAY_BE_TRANSFORMED |
                       NS_FRAME_MAY_HAVE_GENERATED_CONTENT |
                       NS_FRAME_CAN_HAVE_ABSPOS_CHILDREN);
  } else {
    PresContext()->ConstructedFrame();
  }
  if (GetParent()) {
    nsFrameState state = GetParent()->GetStateBits();

    // Make bits that are currently off (see constructor) the same:
    mState |= state & (NS_FRAME_INDEPENDENT_SELECTION |
                       NS_FRAME_GENERATED_CONTENT |
                       NS_FRAME_IS_SVG_TEXT |
                       NS_FRAME_IN_POPUP |
                       NS_FRAME_IS_NONDISPLAY);

    if (HasAnyStateBits(NS_FRAME_IN_POPUP) && TrackingVisibility()) {
      // Assume all frames in popups are visible.
      IncApproximateVisibleCount();
    }
  }
  const nsStyleDisplay *disp = StyleDisplay();
  if (disp->HasTransform(this) ||
      (IsFrameOfType(eSupportsCSSTransforms) &&
       nsLayoutUtils::HasAnimationOfProperty(this, eCSSProperty_transform))) {
    // The frame gets reconstructed if we toggle the -moz-transform
    // property, so we can set this bit here and then ignore it.
    mState |= NS_FRAME_MAY_BE_TRANSFORMED;
  }
  if (disp->mPosition == NS_STYLE_POSITION_STICKY &&
      !aPrevInFlow &&
      !(mState & NS_FRAME_IS_NONDISPLAY) &&
      !disp->IsInnerTableStyle()) {
    // Note that we only add first continuations, but we really only
    // want to add first continuation-or-ib-split-siblings.  But since we
    // don't yet know if we're a later part of a block-in-inline split,
    // we'll just add later members of a block-in-inline split here, and
    // then StickyScrollContainer will remove them later.
    // We don't currently support relative positioning of inner table
    // elements (bug 35168), so exclude them from sticky positioning too.
    StickyScrollContainer* ssc =
      StickyScrollContainer::GetStickyScrollContainerForFrame(this);
    if (ssc) {
      ssc->AddFrame(this);
    }
  }

  if (nsLayoutUtils::FontSizeInflationEnabled(PresContext()) || !GetParent()
#ifdef DEBUG
      // We have assertions that check inflation invariants even when
      // font size inflation is not enabled.
      || true
#endif
      ) {
    if (IsFontSizeInflationContainer(this, disp)) {
      AddStateBits(NS_FRAME_FONT_INFLATION_CONTAINER);
      if (!GetParent() ||
          // I'd use NS_FRAME_OUT_OF_FLOW, but it's not set yet.
          disp->IsFloating(this) || disp->IsAbsolutelyPositioned(this)) {
        AddStateBits(NS_FRAME_FONT_INFLATION_FLOW_ROOT);
      }
    }
    NS_ASSERTION(GetParent() ||
                 (GetStateBits() & NS_FRAME_FONT_INFLATION_CONTAINER),
                 "root frame should always be a container");
  }

  if (PresContext()->PresShell()->AssumeAllFramesVisible() &&
      TrackingVisibility()) {
    IncApproximateVisibleCount();
  }

  DidSetStyleContext(nullptr);

  if (::IsXULBoxWrapped(this))
    ::InitBoxMetrics(this, false);
}

void
nsFrame::DestroyFrom(nsIFrame* aDestructRoot)
{
  NS_ASSERTION(!nsContentUtils::IsSafeToRunScript(),
    "destroy called on frame while scripts not blocked");
  NS_ASSERTION(!GetNextSibling() && !GetPrevSibling(),
               "Frames should be removed before destruction.");
  NS_ASSERTION(aDestructRoot, "Must specify destruct root");
  MOZ_ASSERT(!HasAbsolutelyPositionedChildren());
  MOZ_ASSERT(!HasAnyStateBits(NS_FRAME_PART_OF_IBSPLIT),
             "NS_FRAME_PART_OF_IBSPLIT set on non-nsContainerFrame?");

  nsSVGEffects::InvalidateDirectRenderingObservers(this);

  if (StyleDisplay()->mPosition == NS_STYLE_POSITION_STICKY) {
    StickyScrollContainer* ssc =
      StickyScrollContainer::GetStickyScrollContainerForFrame(this);
    if (ssc) {
      ssc->RemoveFrame(this);
    }
  }

  nsPresContext* presContext = PresContext();
  nsIPresShell* shell = presContext->GetPresShell();
  if (mState & NS_FRAME_OUT_OF_FLOW) {
    nsPlaceholderFrame* placeholder = GetPlaceholderFrame();
    NS_ASSERTION(!placeholder || (aDestructRoot != this),
                 "Don't call Destroy() on OOFs, call Destroy() on the placeholder.");
    NS_ASSERTION(!placeholder ||
                 nsLayoutUtils::IsProperAncestorFrame(aDestructRoot, placeholder),
                 "Placeholder relationship should have been torn down already; "
                 "this might mean we have a stray placeholder in the tree.");
    if (placeholder) {
      placeholder->SetOutOfFlowFrame(nullptr);
    }
  }

  bool isPrimaryFrame = (mContent && mContent->GetPrimaryFrame() == this);
  if (isPrimaryFrame) {
    // This needs to happen before we clear our Properties() table.
    ActiveLayerTracker::TransferActivityToContent(this, mContent);

    // Unfortunately, we need to do this for all frames being reframed
    // and not only those whose current style involves CSS transitions,
    // because what matters is whether the new style (not the old)
    // specifies CSS transitions.
    if (presContext->RestyleManager()->IsGecko()) {
      // stylo: ServoRestyleManager does not handle transitions yet, and when
      // it does it probably won't need to track reframed style contexts to
      // initiate transitions correctly.
      GeckoRestyleManager::ReframingStyleContexts* rsc =
        presContext->RestyleManager()->AsGecko()->GetReframingStyleContexts();
      if (rsc) {
        rsc->Put(mContent, mStyleContext);
      }
    }
  }

  if (HasCSSAnimations() || HasCSSTransitions() ||
      EffectSet::GetEffectSet(this)) {
    // If no new frame for this element is created by the end of the
    // restyling process, stop animations and transitions for this frame
    RestyleManager::AnimationsWithDestroyedFrame* adf =
      presContext->RestyleManager()->GetAnimationsWithDestroyedFrame();
    // AnimationsWithDestroyedFrame only lives during the restyling process.
    if (adf) {
      adf->Put(mContent, mStyleContext);
    }
  }

  // Disable visibility tracking. Note that we have to do this before we clear
  // frame properties and lose track of whether we were previously visible.
  // XXX(seth): It'd be ideal to assert that we're already marked nonvisible
  // here, but it's unfortunately tricky to guarantee in the face of things like
  // frame reconstruction induced by style changes.
  DisableVisibilityTracking();

  // Ensure that we're not in the approximately visible list anymore.
  PresContext()->GetPresShell()->RemoveFrameFromApproximatelyVisibleList(this);

  shell->NotifyDestroyingFrame(this);

  if (mState & NS_FRAME_EXTERNAL_REFERENCE) {
    shell->ClearFrameRefs(this);
  }

  nsView* view = GetView();
  if (view) {
    view->SetFrame(nullptr);
    view->Destroy();
  }

  // Make sure that our deleted frame can't be returned from GetPrimaryFrame()
  if (isPrimaryFrame) {
    mContent->SetPrimaryFrame(nullptr);
  }

  // Delete all properties attached to the frame, to ensure any property
  // destructors that need the frame pointer are handled properly.
  DeleteAllProperties();

  // Must retrieve the object ID before calling destructors, so the
  // vtable is still valid.
  //
  // Note to future tweakers: having the method that returns the
  // object size call the destructor will not avoid an indirect call;
  // the compiler cannot devirtualize the call to the destructor even
  // if it's from a method defined in the same class.

  nsQueryFrame::FrameIID id = GetFrameId();
  this->~nsFrame();

  // Now that we're totally cleaned out, we need to add ourselves to
  // the presshell's recycler.
  shell->FreeFrame(id, this);
}

nsresult
nsFrame::GetOffsets(int32_t &aStart, int32_t &aEnd) const
{
  aStart = 0;
  aEnd = 0;
  return NS_OK;
}

static
void
AddAndRemoveImageAssociations(nsFrame* aFrame,
                              const nsStyleImageLayers* aOldLayers,
                              const nsStyleImageLayers* aNewLayers)
{
   ImageLoader* imageLoader =
     aFrame->PresContext()->Document()->StyleImageLoader();

  // If the old context had a background-image image, or mask-image image,
  // and new context does not have the same image, clear the image load
  // notifier (which keeps the image loading, if it still is) for the frame.
  // We want to do this conservatively because some frames paint their
  // backgrounds from some other frame's style data, and we don't want
  // to clear those notifiers unless we have to.  (They'll be reset
  // when we paint, although we could miss a notification in that
  // interval.)

  if (aOldLayers) {
    NS_FOR_VISIBLE_IMAGE_LAYERS_BACK_TO_FRONT(i, (*aOldLayers)) {
      // If there is an image in oldBG that's not in newBG, drop it.
      if (i >= aNewLayers->mImageCount ||
          !aOldLayers->mLayers[i].mImage.ImageDataEquals(
            aNewLayers->mLayers[i].mImage)) {
        const nsStyleImage& oldImage = aOldLayers->mLayers[i].mImage;
        if (oldImage.GetType() != eStyleImageType_Image) {
          continue;
        }

        if (imgRequestProxy* req = oldImage.GetImageData()) {
          imageLoader->DisassociateRequestFromFrame(req, aFrame);
        }
      }
    }
  }

  NS_FOR_VISIBLE_IMAGE_LAYERS_BACK_TO_FRONT(i, (*aNewLayers)) {
    // If there is an image in newBG that's not in oldBG, add it.
    if (!aOldLayers || i >= aOldLayers->mImageCount ||
        !aNewLayers->mLayers[i].mImage.ImageDataEquals(
          aOldLayers->mLayers[i].mImage)) {
      const nsStyleImage& newImage = aNewLayers->mLayers[i].mImage;
      if (newImage.GetType() != eStyleImageType_Image) {
        continue;
      }

      if (imgRequestProxy* req = newImage.GetImageData()) {
        imageLoader->AssociateRequestToFrame(req, aFrame);
      }
    }
  }
}

// Subclass hook for style post processing
/* virtual */ void
nsFrame::DidSetStyleContext(nsStyleContext* aOldStyleContext)
{
  if (nsSVGUtils::IsInSVGTextSubtree(this)) {
    SVGTextFrame* svgTextFrame = static_cast<SVGTextFrame*>(
      nsLayoutUtils::GetClosestFrameOfType(this, LayoutFrameType::SVGText));
    nsIFrame* anonBlock = svgTextFrame->PrincipalChildList().FirstChild();
    // Just as in SVGTextFrame::DidSetStyleContext, we need to ensure that
    // any non-display SVGTextFrames get reflowed when a child text frame
    // gets new style.
    //
    // Note that we must check NS_FRAME_FIRST_REFLOW on our SVGTextFrame's
    // anonymous block frame rather than our self, since NS_FRAME_FIRST_REFLOW
    // may be set on us if we're a new frame that has been inserted after the
    // document's first reflow. (In which case this DidSetStyleContext call may
    // be happening under frame construction under a Reflow() call.)
    if (anonBlock && !(anonBlock->GetStateBits() & NS_FRAME_FIRST_REFLOW) &&
        (svgTextFrame->GetStateBits() & NS_FRAME_IS_NONDISPLAY) &&
        !(svgTextFrame->GetStateBits() & NS_STATE_SVG_TEXT_IN_REFLOW)) {
      svgTextFrame->ScheduleReflowSVGNonDisplayText(nsIPresShell::eStyleChange);
    }
  }

  const nsStyleImageLayers *oldLayers = aOldStyleContext ?
                              &aOldStyleContext->StyleBackground()->mImage :
                              nullptr;
  const nsStyleImageLayers *newLayers = &StyleBackground()->mImage;
  AddAndRemoveImageAssociations(this, oldLayers, newLayers);

  oldLayers = aOldStyleContext ? &aOldStyleContext->StyleSVGReset()->mMask :
                                  nullptr;
  newLayers = &StyleSVGReset()->mMask;
  AddAndRemoveImageAssociations(this, oldLayers, newLayers);

  if (aOldStyleContext) {
    // If we detect a change on margin, padding or border, we store the old
    // values on the frame itself between now and reflow, so if someone
    // calls GetUsed(Margin|Border|Padding)() before the next reflow, we
    // can give an accurate answer.
    // We don't want to set the property if one already exists.
    nsMargin oldValue(0, 0, 0, 0);
    nsMargin newValue(0, 0, 0, 0);
    const nsStyleMargin* oldMargin = aOldStyleContext->PeekStyleMargin();
    if (oldMargin && oldMargin->GetMargin(oldValue)) {
      if ((!StyleMargin()->GetMargin(newValue) || oldValue != newValue) &&
          !HasProperty(UsedMarginProperty())) {
        AddProperty(UsedMarginProperty(), new nsMargin(oldValue));
      }
    }

    const nsStylePadding* oldPadding = aOldStyleContext->PeekStylePadding();
    if (oldPadding && oldPadding->GetPadding(oldValue)) {
      if ((!StylePadding()->GetPadding(newValue) || oldValue != newValue) &&
          !HasProperty(UsedPaddingProperty())) {
        AddProperty(UsedPaddingProperty(), new nsMargin(oldValue));
      }
    }

    const nsStyleBorder* oldBorder = aOldStyleContext->PeekStyleBorder();
    if (oldBorder) {
      oldValue = oldBorder->GetComputedBorder();
      newValue = StyleBorder()->GetComputedBorder();
      if (oldValue != newValue &&
          !HasProperty(UsedBorderProperty())) {
        AddProperty(UsedBorderProperty(), new nsMargin(oldValue));
      }
    }
  }

  ImageLoader* imageLoader = PresContext()->Document()->StyleImageLoader();
  imgIRequest *oldBorderImage = aOldStyleContext
    ? aOldStyleContext->StyleBorder()->GetBorderImageRequest()
    : nullptr;
  imgIRequest *newBorderImage = StyleBorder()->GetBorderImageRequest();
  // FIXME (Bug 759996): The following is no longer true.
  // For border-images, we can't be as conservative (we need to set the
  // new loaders if there has been any change) since the CalcDifference
  // call depended on the result of GetComputedBorder() and that result
  // depends on whether the image has loaded, start the image load now
  // so that we'll get notified when it completes loading and can do a
  // restyle.  Otherwise, the image might finish loading from the
  // network before we start listening to its notifications, and then
  // we'll never know that it's finished loading.  Likewise, we want to
  // do this for freshly-created frames to prevent a similar race if the
  // image loads between reflow (which can depend on whether the image
  // is loaded) and paint.  We also don't really care about any callers
  // who try to paint borders with a different style context, because
  // they won't have the correct size for the border either.
  if (oldBorderImage != newBorderImage) {
    // stop and restart the image loading/notification
    if (oldBorderImage) {
      imageLoader->DisassociateRequestFromFrame(oldBorderImage, this);
    }
    if (newBorderImage) {
      imageLoader->AssociateRequestToFrame(newBorderImage, this);
    }
  }

  // If the page contains markup that overrides text direction, and
  // does not contain any characters that would activate the Unicode
  // bidi algorithm, we need to call |SetBidiEnabled| on the pres
  // context before reflow starts.  See bug 115921.
  if (StyleVisibility()->mDirection == NS_STYLE_DIRECTION_RTL) {
    PresContext()->SetBidiEnabled();
  }

  RemoveStateBits(NS_FRAME_SIMPLE_EVENT_REGIONS |
                  NS_FRAME_SIMPLE_DISPLAYLIST);

  mMayHaveRoundedCorners = true;
}

void
nsIFrame::ReparentFrameViewTo(nsViewManager* aViewManager,
                              nsView*        aNewParentView,
                              nsView*        aOldParentView)
{
  if (HasView()) {
#ifdef MOZ_XUL
    if (IsMenuPopupFrame()) {
      // This view must be parented by the root view, don't reparent it.
      return;
    }
#endif
    nsView* view = GetView();
    // Verify that the current parent view is what we think it is
    //nsView*  parentView;
    //NS_ASSERTION(parentView == aOldParentView, "unexpected parent view");

    aViewManager->RemoveChild(view);
    
    // The view will remember the Z-order and other attributes that have been set on it.
    nsView* insertBefore = nsLayoutUtils::FindSiblingViewFor(aNewParentView, this);
    aViewManager->InsertChild(aNewParentView, view, insertBefore, insertBefore != nullptr);
  } else if (GetStateBits() & NS_FRAME_HAS_CHILD_WITH_VIEW) {
    nsIFrame::ChildListIterator lists(this);
    for (; !lists.IsDone(); lists.Next()) {
      // Iterate the child frames, and check each child frame to see if it has
      // a view
      nsFrameList::Enumerator childFrames(lists.CurrentList());
      for (; !childFrames.AtEnd(); childFrames.Next()) {
        childFrames.get()->ReparentFrameViewTo(aViewManager, aNewParentView,
                                               aOldParentView);
      }
    }
  }
}

void
nsIFrame::SyncFrameViewProperties(nsView* aView)
{
  if (!aView) {
    aView = GetView();
    if (!aView) {
      return;
    }
  }

  nsViewManager* vm = aView->GetViewManager();

  // Make sure visibility is correct. This only affects nsSubDocumentFrame.
  if (!SupportsVisibilityHidden()) {
    // See if the view should be hidden or visible
    nsStyleContext* sc = StyleContext();
    vm->SetViewVisibility(aView,
        sc->StyleVisibility()->IsVisible()
            ? nsViewVisibility_kShow : nsViewVisibility_kHide);
  }

  int32_t zIndex = 0;
  bool    autoZIndex = false;

  if (IsAbsPosContainingBlock()) {
    // Make sure z-index is correct
    nsStyleContext* sc = StyleContext();
    const nsStylePosition* position = sc->StylePosition();
    if (position->mZIndex.GetUnit() == eStyleUnit_Integer) {
      zIndex = position->mZIndex.GetIntValue();
    } else if (position->mZIndex.GetUnit() == eStyleUnit_Auto) {
      autoZIndex = true;
    }
  } else {
    autoZIndex = true;
  }

  vm->SetViewZIndex(aView, autoZIndex, zIndex);
}

void
nsFrame::CreateView()
{
  MOZ_ASSERT(!HasView());

  nsView* parentView = GetParent()->GetClosestView();
  MOZ_ASSERT(parentView, "no parent with view");

  nsViewManager* viewManager = parentView->GetViewManager();
  MOZ_ASSERT(viewManager, "null view manager");

  nsView* view = viewManager->CreateView(GetRect(), parentView);
  SyncFrameViewProperties(view);

  nsView* insertBefore = nsLayoutUtils::FindSiblingViewFor(parentView, this);
  // we insert this view 'above' the insertBefore view, unless insertBefore is null,
  // in which case we want to call with aAbove == false to insert at the beginning
  // in document order
  viewManager->InsertChild(parentView, view, insertBefore, insertBefore != nullptr);

  // REVIEW: Don't create a widget for fixed-pos elements anymore.
  // ComputeRepaintRegionForCopy will calculate the right area to repaint
  // when we scroll.
  // Reparent views on any child frames (or their descendants) to this
  // view. We can just call ReparentFrameViewTo on this frame because
  // we know this frame has no view, so it will crawl the children. Also,
  // we know that any descendants with views must have 'parentView' as their
  // parent view.
  ReparentFrameViewTo(viewManager, view, parentView);

  // Remember our view
  SetView(view);

  NS_FRAME_LOG(NS_FRAME_TRACE_CALLS,
               ("nsFrame::CreateView: frame=%p view=%p",
                this, view));
}

// MSVC fails with link error "one or more multiply defined symbols found",
// gcc fails with "hidden symbol `nsIFrame::kPrincipalList' isn't defined"
// etc if they are not defined.
#ifndef _MSC_VER
// static nsIFrame constants; initialized in the header file.
const nsIFrame::ChildListID nsIFrame::kPrincipalList;
const nsIFrame::ChildListID nsIFrame::kAbsoluteList;
const nsIFrame::ChildListID nsIFrame::kBulletList;
const nsIFrame::ChildListID nsIFrame::kCaptionList;
const nsIFrame::ChildListID nsIFrame::kColGroupList;
const nsIFrame::ChildListID nsIFrame::kExcessOverflowContainersList;
const nsIFrame::ChildListID nsIFrame::kFixedList;
const nsIFrame::ChildListID nsIFrame::kFloatList;
const nsIFrame::ChildListID nsIFrame::kOverflowContainersList;
const nsIFrame::ChildListID nsIFrame::kOverflowList;
const nsIFrame::ChildListID nsIFrame::kOverflowOutOfFlowList;
const nsIFrame::ChildListID nsIFrame::kPopupList;
const nsIFrame::ChildListID nsIFrame::kPushedFloatsList;
const nsIFrame::ChildListID nsIFrame::kSelectPopupList;
const nsIFrame::ChildListID nsIFrame::kNoReflowPrincipalList;
#endif

/* virtual */ nsMargin
nsIFrame::GetUsedMargin() const
{
  nsMargin margin(0, 0, 0, 0);
  if (((mState & NS_FRAME_FIRST_REFLOW) &&
       !(mState & NS_FRAME_IN_REFLOW)) ||
      nsSVGUtils::IsInSVGTextSubtree(this))
    return margin;

  nsMargin *m = GetProperty(UsedMarginProperty());
  if (m) {
    margin = *m;
  } else {
    if (!StyleMargin()->GetMargin(margin)) {
      // If we get here, our caller probably shouldn't be calling us...
      NS_ERROR("Returning bogus 0-sized margin, because this margin "
               "depends on layout & isn't cached!");
    }
  }
  return margin;
}

/* virtual */ nsMargin
nsIFrame::GetUsedBorder() const
{
  nsMargin border(0, 0, 0, 0);
  if (((mState & NS_FRAME_FIRST_REFLOW) &&
       !(mState & NS_FRAME_IN_REFLOW)) ||
      nsSVGUtils::IsInSVGTextSubtree(this))
    return border;

  // Theme methods don't use const-ness.
  nsIFrame *mutable_this = const_cast<nsIFrame*>(this);

  const nsStyleDisplay *disp = StyleDisplay();
  if (mutable_this->IsThemed(disp)) {
    nsIntMargin result;
    nsPresContext *presContext = PresContext();
    presContext->GetTheme()->GetWidgetBorder(presContext->DeviceContext(),
                                             mutable_this, disp->mAppearance,
                                             &result);
    border.left = presContext->DevPixelsToAppUnits(result.left);
    border.top = presContext->DevPixelsToAppUnits(result.top);
    border.right = presContext->DevPixelsToAppUnits(result.right);
    border.bottom = presContext->DevPixelsToAppUnits(result.bottom);
    return border;
  }

  nsMargin *b = GetProperty(UsedBorderProperty());
  if (b) {
    border = *b;
  } else {
    border = StyleBorder()->GetComputedBorder();
  }
  return border;
}

/* virtual */ nsMargin
nsIFrame::GetUsedPadding() const
{
  nsMargin padding(0, 0, 0, 0);
  if (((mState & NS_FRAME_FIRST_REFLOW) &&
       !(mState & NS_FRAME_IN_REFLOW)) ||
      nsSVGUtils::IsInSVGTextSubtree(this))
    return padding;

  // Theme methods don't use const-ness.
  nsIFrame *mutable_this = const_cast<nsIFrame*>(this);

  const nsStyleDisplay *disp = StyleDisplay();
  if (mutable_this->IsThemed(disp)) {
    nsPresContext *presContext = PresContext();
    nsIntMargin widget;
    if (presContext->GetTheme()->GetWidgetPadding(presContext->DeviceContext(),
                                                  mutable_this,
                                                  disp->mAppearance,
                                                  &widget)) {
      padding.top = presContext->DevPixelsToAppUnits(widget.top);
      padding.right = presContext->DevPixelsToAppUnits(widget.right);
      padding.bottom = presContext->DevPixelsToAppUnits(widget.bottom);
      padding.left = presContext->DevPixelsToAppUnits(widget.left);
      return padding;
    }
  }

  nsMargin *p = GetProperty(UsedPaddingProperty());
  if (p) {
    padding = *p;
  } else {
    if (!StylePadding()->GetPadding(padding)) {
      // If we get here, our caller probably shouldn't be calling us...
      NS_ERROR("Returning bogus 0-sized padding, because this padding "
               "depends on layout & isn't cached!");
    }
  }
  return padding;
}

nsIFrame::Sides
nsIFrame::GetSkipSides(const ReflowInput* aReflowInput) const
{
  if (MOZ_UNLIKELY(StyleBorder()->mBoxDecorationBreak ==
                     StyleBoxDecorationBreak::Clone) &&
      !(GetStateBits() & NS_FRAME_IS_OVERFLOW_CONTAINER)) {
    return Sides();
  }

  // Convert the logical skip sides to physical sides using the frame's
  // writing mode
  WritingMode writingMode = GetWritingMode();
  LogicalSides logicalSkip = GetLogicalSkipSides(aReflowInput);
  Sides skip;

  if (logicalSkip.BStart()) {
    if (writingMode.IsVertical()) {
      skip |= writingMode.IsVerticalLR() ? eSideBitsLeft : eSideBitsRight;
    } else {
      skip |= eSideBitsTop;
    }
  }

  if (logicalSkip.BEnd()) {
    if (writingMode.IsVertical()) {
      skip |= writingMode.IsVerticalLR() ? eSideBitsRight : eSideBitsLeft;
    } else {
      skip |= eSideBitsBottom;
    }
  }

  if (logicalSkip.IStart()) {
    if (writingMode.IsVertical()) {
      skip |= eSideBitsTop;
    } else {
      skip |= writingMode.IsBidiLTR() ? eSideBitsLeft : eSideBitsRight;
    }
  }

  if (logicalSkip.IEnd()) {
    if (writingMode.IsVertical()) {
      skip |= eSideBitsBottom;
    } else {
      skip |= writingMode.IsBidiLTR() ? eSideBitsRight : eSideBitsLeft;
    }
  }
  return skip;
}

nsRect
nsIFrame::GetPaddingRectRelativeToSelf() const
{
  nsMargin border(GetUsedBorder());
  border.ApplySkipSides(GetSkipSides());
  nsRect r(0, 0, mRect.width, mRect.height);
  r.Deflate(border);
  return r;
}

nsRect
nsIFrame::GetPaddingRect() const
{
  return GetPaddingRectRelativeToSelf() + GetPosition();
}

WritingMode
nsIFrame::WritingModeForLine(WritingMode aSelfWM,
                             nsIFrame*   aSubFrame) const
{
  MOZ_ASSERT(aSelfWM == GetWritingMode());
  WritingMode writingMode = aSelfWM;

  if (StyleTextReset()->mUnicodeBidi & NS_STYLE_UNICODE_BIDI_PLAINTEXT) {
    nsBidiLevel frameLevel = nsBidiPresUtils::GetFrameBaseLevel(aSubFrame);
    writingMode.SetDirectionFromBidiLevel(frameLevel);
  }

  return writingMode;
}

nsRect
nsIFrame::GetMarginRectRelativeToSelf() const
{
  nsMargin m = GetUsedMargin();
  m.ApplySkipSides(GetSkipSides());
  nsRect r(0, 0, mRect.width, mRect.height);
  r.Inflate(m);
  return r;
}

bool
nsIFrame::IsTransformed(const nsStyleDisplay* aStyleDisplay,
                        EffectSet* aEffectSet) const
{
  MOZ_ASSERT(aStyleDisplay == StyleDisplay());
  return ((mState & NS_FRAME_MAY_BE_TRANSFORMED) &&
          (aStyleDisplay->HasTransform(this) ||
           IsSVGTransformed() ||
           HasAnimationOfTransform(aEffectSet)));
}

bool
nsIFrame::HasAnimationOfTransform(EffectSet* aEffectSet) const
{
  EffectSet* effects =
    aEffectSet ? aEffectSet : EffectSet::GetEffectSet(this);

  return mContent &&
    nsLayoutUtils::HasAnimationOfProperty(effects, eCSSProperty_transform) &&
    IsFrameOfType(eSupportsCSSTransforms) &&
    mContent->GetPrimaryFrame() == this;
}

bool
nsIFrame::HasOpacityInternal(float aThreshold,
                             EffectSet* aEffectSet) const
{
  MOZ_ASSERT(0.0 <= aThreshold && aThreshold <= 1.0, "Invalid argument");
  if (StyleEffects()->mOpacity < aThreshold ||
      (StyleDisplay()->mWillChangeBitField & NS_STYLE_WILL_CHANGE_OPACITY)) {
    return true;
  }

  EffectSet* effects =
    aEffectSet ? aEffectSet : EffectSet::GetEffectSet(this);
  return (mContent && mContent->GetPrimaryFrame() == this &&
          nsLayoutUtils::HasAnimationOfProperty(effects, eCSSProperty_opacity));
}

bool
nsIFrame::IsSVGTransformed(gfx::Matrix *aOwnTransforms,
                           gfx::Matrix *aFromParentTransforms) const
{
  return false;
}

bool
nsIFrame::Extend3DContext(const nsStyleDisplay* aStyleDisplay, mozilla::EffectSet* aEffectSet) const
{
  const nsStyleDisplay* disp = StyleDisplayWithOptionalParam(aStyleDisplay);
  if (disp->mTransformStyle != NS_STYLE_TRANSFORM_STYLE_PRESERVE_3D ||
      !IsFrameOfType(nsIFrame::eSupportsCSSTransforms)) {
    return false;
  }

  // If we're all scroll frame, then all descendants will be clipped, so we can't preserve 3d.
  if (IsScrollFrame()) {
    return false;
  }

  if (HasOpacity(aEffectSet)) {
    return false;
  }

  const nsStyleEffects* effects = StyleEffects();
  return !nsFrame::ShouldApplyOverflowClipping(this, disp) &&
         !GetClipPropClipRect(disp, effects, GetSize()) &&
         !nsSVGIntegrationUtils::UsingEffectsForFrame(this);
}

bool
nsIFrame::Combines3DTransformWithAncestors(const nsStyleDisplay* aStyleDisplay,
                                           EffectSet* aEffectSet) const
{
  MOZ_ASSERT(aStyleDisplay == StyleDisplay());
  nsIFrame* parent = GetFlattenedTreeParentPrimaryFrame();
  if (!parent || !parent->Extend3DContext()) {
    return false;
  }
  return IsTransformed(aStyleDisplay,aEffectSet) ||
         BackfaceIsHidden(aStyleDisplay);
}

bool
nsIFrame::In3DContextAndBackfaceIsHidden(EffectSet* aEffectSet) const
{
  // While both tests fail most of the time, test BackfaceIsHidden()
  // first since it's likely to fail faster.
  const nsStyleDisplay* disp = StyleDisplay();
  return BackfaceIsHidden(disp) &&
         Combines3DTransformWithAncestors(disp, aEffectSet);
}

bool
nsIFrame::HasPerspective(const nsStyleDisplay* aStyleDisplay, EffectSet* aEffectSet) const
{
  MOZ_ASSERT(aStyleDisplay == StyleDisplay());
  if (!IsTransformed(aStyleDisplay, aEffectSet)) {
    return false;
  }
  nsIFrame* containingBlock = GetContainingBlock(SKIP_SCROLLED_FRAME, aStyleDisplay);
  if (!containingBlock) {
    return false;
  }
  return containingBlock->ChildrenHavePerspective();
}

nsRect
nsIFrame::GetContentRectRelativeToSelf() const
{
  nsMargin bp(GetUsedBorderAndPadding());
  bp.ApplySkipSides(GetSkipSides());
  nsRect r(0, 0, mRect.width, mRect.height);
  r.Deflate(bp);
  return r;
}

nsRect
nsIFrame::GetContentRect() const
{
  return GetContentRectRelativeToSelf() + GetPosition();
}

bool
nsIFrame::ComputeBorderRadii(const nsStyleCorners& aBorderRadius,
                             const nsSize& aFrameSize,
                             const nsSize& aBorderArea,
                             Sides aSkipSides,
                             nscoord aRadii[8])
{
  // Percentages are relative to whichever side they're on.
  NS_FOR_CSS_HALF_CORNERS(i) {
    const nsStyleCoord c = aBorderRadius.Get(i);
    nscoord axis =
      HalfCornerIsX(i) ? aFrameSize.width : aFrameSize.height;

    if (c.IsCoordPercentCalcUnit()) {
      aRadii[i] = nsRuleNode::ComputeCoordPercentCalc(c, axis);
      if (aRadii[i] < 0) {
        // clamp calc()
        aRadii[i] = 0;
      }
    } else {
      NS_NOTREACHED("ComputeBorderRadii: bad unit");
      aRadii[i] = 0;
    }
  }

  if (aSkipSides.Top()) {
    aRadii[eCornerTopLeftX] = 0;
    aRadii[eCornerTopLeftY] = 0;
    aRadii[eCornerTopRightX] = 0;
    aRadii[eCornerTopRightY] = 0;
  }

  if (aSkipSides.Right()) {
    aRadii[eCornerTopRightX] = 0;
    aRadii[eCornerTopRightY] = 0;
    aRadii[eCornerBottomRightX] = 0;
    aRadii[eCornerBottomRightY] = 0;
  }

  if (aSkipSides.Bottom()) {
    aRadii[eCornerBottomRightX] = 0;
    aRadii[eCornerBottomRightY] = 0;
    aRadii[eCornerBottomLeftX] = 0;
    aRadii[eCornerBottomLeftY] = 0;
  }

  if (aSkipSides.Left()) {
    aRadii[eCornerBottomLeftX] = 0;
    aRadii[eCornerBottomLeftY] = 0;
    aRadii[eCornerTopLeftX] = 0;
    aRadii[eCornerTopLeftY] = 0;
  }

  // css3-background specifies this algorithm for reducing
  // corner radii when they are too big.
  bool haveRadius = false;
  double ratio = 1.0f;
  NS_FOR_CSS_SIDES(side) {
    uint32_t hc1 = SideToHalfCorner(side, false, true);
    uint32_t hc2 = SideToHalfCorner(side, true, true);
    nscoord length =
      SideIsVertical(side) ? aBorderArea.height : aBorderArea.width;
    nscoord sum = aRadii[hc1] + aRadii[hc2];
    if (sum)
      haveRadius = true;

    // avoid floating point division in the normal case
    if (length < sum)
      ratio = std::min(ratio, double(length)/sum);
  }
  if (ratio < 1.0) {
    NS_FOR_CSS_HALF_CORNERS(corner) {
      aRadii[corner] *= ratio;
    }
  }

  return haveRadius;
}

/* static */ void
nsIFrame::InsetBorderRadii(nscoord aRadii[8], const nsMargin &aOffsets)
{
  NS_FOR_CSS_SIDES(side) {
    nscoord offset = aOffsets.Side(side);
    uint32_t hc1 = SideToHalfCorner(side, false, false);
    uint32_t hc2 = SideToHalfCorner(side, true, false);
    aRadii[hc1] = std::max(0, aRadii[hc1] - offset);
    aRadii[hc2] = std::max(0, aRadii[hc2] - offset);
  }
}

/* static */ void
nsIFrame::OutsetBorderRadii(nscoord aRadii[8], const nsMargin &aOffsets)
{
  auto AdjustOffset = [] (const uint32_t aRadius, const nscoord aOffset) {
    // Implement the cubic formula to adjust offset when aOffset > 0 and
    // aRadius / aOffset < 1.
    // https://drafts.csswg.org/css-shapes/#valdef-shape-box-margin-box
    if (aOffset > 0) {
      const double ratio = aRadius / double(aOffset);
      if (ratio < 1.0) {
        return nscoord(aOffset * (1.0 + std::pow(ratio - 1, 3)));
      }
    }
    return aOffset;
  };

  NS_FOR_CSS_SIDES(side) {
    const nscoord offset = aOffsets.Side(side);
    const uint32_t hc1 = SideToHalfCorner(side, false, false);
    const uint32_t hc2 = SideToHalfCorner(side, true, false);
    if (aRadii[hc1] > 0) {
      const nscoord offset1 = AdjustOffset(aRadii[hc1], offset);
      aRadii[hc1] = std::max(0, aRadii[hc1] + offset1);
    }
    if (aRadii[hc2] > 0) {
      const nscoord offset2 = AdjustOffset(aRadii[hc2], offset);
      aRadii[hc2] = std::max(0, aRadii[hc2] + offset2);
    }
  }
}

/* virtual */ bool
nsIFrame::GetBorderRadii(const nsSize& aFrameSize, const nsSize& aBorderArea,
                         Sides aSkipSides, nscoord aRadii[8]) const
{
  if (!mMayHaveRoundedCorners) {
    memset(aRadii, 0, sizeof(nscoord) * 8);
    return false;
  }

  if (IsThemed()) {
    // When we're themed, the native theme code draws the border and
    // background, and therefore it doesn't make sense to tell other
    // code that's interested in border-radius that we have any radii.
    //
    // In an ideal world, we might have a way for the them to tell us an
    // border radius, but since we don't, we're better off assuming
    // zero.
    NS_FOR_CSS_HALF_CORNERS(corner) {
      aRadii[corner] = 0;
    }
    return false;
  }

  const_cast<nsIFrame*>(this)->mMayHaveRoundedCorners =
    ComputeBorderRadii(StyleBorder()->mBorderRadius,
                       aFrameSize, aBorderArea,
                       aSkipSides, aRadii);
  return mMayHaveRoundedCorners;
}

bool
nsIFrame::GetBorderRadii(nscoord aRadii[8]) const
{
  nsSize sz = GetSize();
  return GetBorderRadii(sz, sz, GetSkipSides(), aRadii);
}

bool
nsIFrame::GetMarginBoxBorderRadii(nscoord aRadii[8]) const
{
  if (!GetBorderRadii(aRadii)) {
    return false;
  }
  OutsetBorderRadii(aRadii, GetUsedMargin());
  NS_FOR_CSS_HALF_CORNERS(corner) {
    if (aRadii[corner]) {
      return true;
    }
  }
  return false;
}

bool
nsIFrame::GetPaddingBoxBorderRadii(nscoord aRadii[8]) const
{
  if (!GetBorderRadii(aRadii))
    return false;
  InsetBorderRadii(aRadii, GetUsedBorder());
  NS_FOR_CSS_HALF_CORNERS(corner) {
    if (aRadii[corner])
      return true;
  }
  return false;
}

bool
nsIFrame::GetContentBoxBorderRadii(nscoord aRadii[8]) const
{
  if (!GetBorderRadii(aRadii))
    return false;
  InsetBorderRadii(aRadii, GetUsedBorderAndPadding());
  NS_FOR_CSS_HALF_CORNERS(corner) {
    if (aRadii[corner])
      return true;
  }
  return false;
}

bool
nsIFrame::GetShapeBoxBorderRadii(nscoord aRadii[8]) const
{
  switch (StyleDisplay()->mShapeOutside.GetReferenceBox()) {
    case StyleGeometryBox::NoBox:
      return false;
    case StyleGeometryBox::ContentBox:
      return GetContentBoxBorderRadii(aRadii);
    case StyleGeometryBox::PaddingBox:
      return GetPaddingBoxBorderRadii(aRadii);
    case StyleGeometryBox::BorderBox:
      return GetBorderRadii(aRadii);
    case StyleGeometryBox::MarginBox:
      return GetMarginBoxBorderRadii(aRadii);
    default:
      MOZ_ASSERT_UNREACHABLE("Unexpected box value");
      return false;
  }
  return false;
}

nsStyleContext*
nsFrame::GetAdditionalStyleContext(int32_t aIndex) const
{
  NS_PRECONDITION(aIndex >= 0, "invalid index number");
  return nullptr;
}

void
nsFrame::SetAdditionalStyleContext(int32_t aIndex, 
                                   nsStyleContext* aStyleContext)
{
  NS_PRECONDITION(aIndex >= 0, "invalid index number");
}

nscoord
nsFrame::GetLogicalBaseline(WritingMode aWritingMode) const
{
  NS_ASSERTION(!NS_SUBTREE_DIRTY(this),
               "frame must not be dirty");
  // Baseline for inverted line content is the top (block-start) margin edge,
  // as the frame is in effect "flipped" for alignment purposes.
  if (aWritingMode.IsLineInverted()) {
    return -GetLogicalUsedMargin(aWritingMode).BStart(aWritingMode);
  }
  // Otherwise, the bottom margin edge, per CSS2.1's definition of the
  // 'baseline' value of 'vertical-align'.
  return BSize(aWritingMode) +
         GetLogicalUsedMargin(aWritingMode).BEnd(aWritingMode);
}

const nsFrameList&
nsFrame::GetChildList(ChildListID aListID) const
{
  if (IsAbsoluteContainer() &&
      aListID == GetAbsoluteListID()) {
    return GetAbsoluteContainingBlock()->GetChildList();
  } else {
    return nsFrameList::EmptyList();
  }
}

void
nsFrame::GetChildLists(nsTArray<ChildList>* aLists) const
{
  if (IsAbsoluteContainer()) {
    nsFrameList absoluteList = GetAbsoluteContainingBlock()->GetChildList();
    absoluteList.AppendIfNonempty(aLists, GetAbsoluteListID());
  }
}

void
nsIFrame::GetCrossDocChildLists(nsTArray<ChildList>* aLists)
{
  nsSubDocumentFrame* subdocumentFrame = do_QueryFrame(this);
  if (subdocumentFrame) {
    // Descend into the subdocument
    nsIFrame* root = subdocumentFrame->GetSubdocumentRootFrame();
    if (root) {
      aLists->AppendElement(nsIFrame::ChildList(
        nsFrameList(root, nsLayoutUtils::GetLastSibling(root)),
        nsIFrame::kPrincipalList));
    }
  }

  GetChildLists(aLists);
}

Visibility
nsIFrame::GetVisibility() const
{
  if (!(GetStateBits() & NS_FRAME_VISIBILITY_IS_TRACKED)) {
    return Visibility::UNTRACKED;
  }

  bool isSet = false;
  uint32_t visibleCount = GetProperty(VisibilityStateProperty(), &isSet);

  MOZ_ASSERT(isSet, "Should have a VisibilityStateProperty value "
                    "if NS_FRAME_VISIBILITY_IS_TRACKED is set");

  return visibleCount > 0
       ? Visibility::APPROXIMATELY_VISIBLE
       : Visibility::APPROXIMATELY_NONVISIBLE;
}

void
nsIFrame::UpdateVisibilitySynchronously()
{
  nsIPresShell* presShell = PresContext()->PresShell();
  if (!presShell) {
    return;
  }

  if (presShell->AssumeAllFramesVisible()) {
    presShell->EnsureFrameInApproximatelyVisibleList(this);
    return;
  }

  bool visible = StyleVisibility()->IsVisible();
  nsIFrame* f = GetParent();
  nsRect rect = GetRectRelativeToSelf();
  nsIFrame* rectFrame = this;
  while (f && visible) {
    nsIScrollableFrame* sf = do_QueryFrame(f);
    if (sf) {
      nsRect transformedRect =
        nsLayoutUtils::TransformFrameRectToAncestor(rectFrame, rect, f);
      if (!sf->IsRectNearlyVisible(transformedRect)) {
        visible = false;
        break;
      }

      // In this code we're trying to synchronously update *approximate*
      // visibility. (In the future we may update precise visibility here as
      // well, which is why the method name does not contain 'approximate'.) The
      // IsRectNearlyVisible() check above tells us that the rect we're checking
      // is approximately visible within the scrollframe, but we still need to
      // ensure that, even if it was scrolled into view, it'd be visible when we
      // consider the rest of the document. To do that, we move transformedRect
      // to be contained in the scrollport as best we can (it might not fit) to
      // pretend that it was scrolled into view.
      rect = transformedRect.MoveInsideAndClamp(sf->GetScrollPortRect());
      rectFrame = f;
    }
    nsIFrame* parent = f->GetParent();
    if (!parent) {
      parent = nsLayoutUtils::GetCrossDocParentFrame(f);
      if (parent && parent->PresContext()->IsChrome()) {
        break;
      }
    }
    f = parent;
  }

  if (visible) {
    presShell->EnsureFrameInApproximatelyVisibleList(this);
  } else {
    presShell->RemoveFrameFromApproximatelyVisibleList(this);
  }
}

void
nsIFrame::EnableVisibilityTracking()
{
  if (GetStateBits() & NS_FRAME_VISIBILITY_IS_TRACKED) {
    return;  // Nothing to do.
  }

  MOZ_ASSERT(!HasProperty(VisibilityStateProperty()),
             "Shouldn't have a VisibilityStateProperty value "
             "if NS_FRAME_VISIBILITY_IS_TRACKED is not set");

  // Add the state bit so we know to track visibility for this frame, and
  // initialize the frame property.
  AddStateBits(NS_FRAME_VISIBILITY_IS_TRACKED);
  SetProperty(VisibilityStateProperty(), 0);

  nsIPresShell* presShell = PresContext()->PresShell();
  if (!presShell) {
    return;
  }

  // Schedule a visibility update. This method will virtually always be called
  // when layout has changed anyway, so it's very unlikely that any additional
  // visibility updates will be triggered by this, but this way we guarantee
  // that if this frame is currently visible we'll eventually find out.
  presShell->ScheduleApproximateFrameVisibilityUpdateSoon();
}

void
nsIFrame::DisableVisibilityTracking()
{
  if (!(GetStateBits() & NS_FRAME_VISIBILITY_IS_TRACKED)) {
    return;  // Nothing to do.
  }

  bool isSet = false;
  uint32_t visibleCount = RemoveProperty(VisibilityStateProperty(), &isSet);

  MOZ_ASSERT(isSet, "Should have a VisibilityStateProperty value "
                    "if NS_FRAME_VISIBILITY_IS_TRACKED is set");

  RemoveStateBits(NS_FRAME_VISIBILITY_IS_TRACKED);

  if (visibleCount == 0) {
    return;  // We were nonvisible.
  }

  // We were visible, so send an OnVisibilityChange() notification.
  OnVisibilityChange(Visibility::APPROXIMATELY_NONVISIBLE);
}

void
nsIFrame::DecApproximateVisibleCount(const Maybe<OnNonvisible>& aNonvisibleAction
                                       /* = Nothing() */)
{
  MOZ_ASSERT(GetStateBits() & NS_FRAME_VISIBILITY_IS_TRACKED);

  bool isSet = false;
  uint32_t visibleCount = GetProperty(VisibilityStateProperty(), &isSet);

  MOZ_ASSERT(isSet, "Should have a VisibilityStateProperty value "
                    "if NS_FRAME_VISIBILITY_IS_TRACKED is set");
  MOZ_ASSERT(visibleCount > 0, "Frame is already nonvisible and we're "
                               "decrementing its visible count?");

  visibleCount--;
  SetProperty(VisibilityStateProperty(), visibleCount);
  if (visibleCount > 0) {
    return;
  }

  // We just became nonvisible, so send an OnVisibilityChange() notification.
  OnVisibilityChange(Visibility::APPROXIMATELY_NONVISIBLE, aNonvisibleAction);
}

void
nsIFrame::IncApproximateVisibleCount()
{
  MOZ_ASSERT(GetStateBits() & NS_FRAME_VISIBILITY_IS_TRACKED);

  bool isSet = false;
  uint32_t visibleCount = GetProperty(VisibilityStateProperty(), &isSet);

  MOZ_ASSERT(isSet, "Should have a VisibilityStateProperty value "
                    "if NS_FRAME_VISIBILITY_IS_TRACKED is set");

  visibleCount++;
  SetProperty(VisibilityStateProperty(), visibleCount);
  if (visibleCount > 1) {
    return;
  }

  // We just became visible, so send an OnVisibilityChange() notification.
  OnVisibilityChange(Visibility::APPROXIMATELY_VISIBLE);
}

void
nsIFrame::OnVisibilityChange(Visibility aNewVisibility,
                             const Maybe<OnNonvisible>& aNonvisibleAction
                               /* = Nothing() */)
{
  // XXX(seth): In bug 1218990 we'll implement visibility tracking for CSS
  // images here.
}

static nsIFrame*
GetActiveSelectionFrame(nsPresContext* aPresContext, nsIFrame* aFrame)
{
  nsIContent* capturingContent = nsIPresShell::GetCapturingContent();
  if (capturingContent) {
    nsIFrame* activeFrame = aPresContext->GetPrimaryFrameFor(capturingContent);
    return activeFrame ? activeFrame : aFrame;
  }

  return aFrame;
}

int16_t
nsFrame::DisplaySelection(nsPresContext* aPresContext, bool isOkToTurnOn)
{
  int16_t selType = nsISelectionController::SELECTION_OFF;

  nsCOMPtr<nsISelectionController> selCon;
  nsresult result = GetSelectionController(aPresContext, getter_AddRefs(selCon));
  if (NS_SUCCEEDED(result) && selCon) {
    result = selCon->GetDisplaySelection(&selType);
    if (NS_SUCCEEDED(result) && (selType != nsISelectionController::SELECTION_OFF)) {
      // Check whether style allows selection.
      if (!IsSelectable(nullptr)) {
        selType = nsISelectionController::SELECTION_OFF;
        isOkToTurnOn = false;
      }
    }
    if (isOkToTurnOn && (selType == nsISelectionController::SELECTION_OFF)) {
      selCon->SetDisplaySelection(nsISelectionController::SELECTION_ON);
      selType = nsISelectionController::SELECTION_ON;
    }
  }
  return selType;
}

class nsDisplaySelectionOverlay : public nsDisplayItem {
public:
  nsDisplaySelectionOverlay(nsDisplayListBuilder* aBuilder,
                            nsFrame* aFrame, int16_t aSelectionValue)
    : nsDisplayItem(aBuilder, aFrame), mSelectionValue(aSelectionValue) {
    MOZ_COUNT_CTOR(nsDisplaySelectionOverlay);
  }
#ifdef NS_BUILD_REFCNT_LOGGING
  virtual ~nsDisplaySelectionOverlay() {
    MOZ_COUNT_DTOR(nsDisplaySelectionOverlay);
  }
#endif

  virtual void Paint(nsDisplayListBuilder* aBuilder,
                     nsRenderingContext* aCtx) override;
  NS_DISPLAY_DECL_NAME("SelectionOverlay", TYPE_SELECTION_OVERLAY)
private:
  int16_t mSelectionValue;
};

void nsDisplaySelectionOverlay::Paint(nsDisplayListBuilder* aBuilder,
                                      nsRenderingContext* aCtx)
{
  DrawTarget& aDrawTarget = *aCtx->GetDrawTarget();

  LookAndFeel::ColorID colorID;
  if (mSelectionValue == nsISelectionController::SELECTION_ON) {
    colorID = LookAndFeel::eColorID_TextSelectBackground;
  } else if (mSelectionValue == nsISelectionController::SELECTION_ATTENTION) {
    colorID = LookAndFeel::eColorID_TextSelectBackgroundAttention;
  } else {
    colorID = LookAndFeel::eColorID_TextSelectBackgroundDisabled;
  }

  Color c = Color::FromABGR(LookAndFeel::GetColor(colorID, NS_RGB(255, 255, 255)));
  c.a = .5;
  ColorPattern color(ToDeviceColor(c));

  nsIntRect pxRect =
    mVisibleRect.ToOutsidePixels(mFrame->PresContext()->AppUnitsPerDevPixel());
  Rect rect(pxRect.x, pxRect.y, pxRect.width, pxRect.height);
  MaybeSnapToDevicePixels(rect, aDrawTarget, true);

  aDrawTarget.FillRect(rect, color);
}

/********************************************************
* Refreshes each content's frame
*********************************************************/

void
nsFrame::DisplaySelectionOverlay(nsDisplayListBuilder*   aBuilder,
                                 nsDisplayList*          aList,
                                 uint16_t                aContentType)
{
  if (!IsSelected() || !IsVisibleForPainting(aBuilder))
    return;
    
  nsPresContext* presContext = PresContext();
  nsIPresShell *shell = presContext->PresShell();
  if (!shell)
    return;

  int16_t displaySelection = shell->GetSelectionFlags();
  if (!(displaySelection & aContentType))
    return;

  const nsFrameSelection* frameSelection = GetConstFrameSelection();
  int16_t selectionValue = frameSelection->GetDisplaySelection();

  if (selectionValue <= nsISelectionController::SELECTION_HIDDEN)
    return; // selection is hidden or off

  nsIContent *newContent = mContent->GetParent();

  //check to see if we are anonymous content
  int32_t offset = 0;
  if (newContent) {
    // XXXbz there has GOT to be a better way of determining this!
    offset = newContent->IndexOf(mContent);
  }

  //look up to see what selection(s) are on this frame
  UniquePtr<SelectionDetails> details
    = frameSelection->LookUpSelection(newContent, offset, 1, false);
  if (!details)
    return;

  bool normal = false;
  for (SelectionDetails* sd = details.get(); sd; sd = sd->mNext.get()) {
    if (sd->mSelectionType == SelectionType::eNormal) {
      normal = true;
    }
  }

  if (!normal && aContentType == nsISelectionDisplay::DISPLAY_IMAGES) {
    // Don't overlay an image if it's not in the primary selection.
    return;
  }

  aList->AppendNewToTop(new (aBuilder)
    nsDisplaySelectionOverlay(aBuilder, this, selectionValue));
}

void
nsFrame::DisplayOutlineUnconditional(nsDisplayListBuilder*   aBuilder,
                                     const nsDisplayListSet& aLists)
{
  if (!StyleOutline()->ShouldPaintOutline()) {
    return;
  }

  aLists.Outlines()->AppendNewToTop(
    new (aBuilder) nsDisplayOutline(aBuilder, this));
}

void
nsFrame::DisplayOutline(nsDisplayListBuilder*   aBuilder,
                        const nsDisplayListSet& aLists)
{
  if (!IsVisibleForPainting(aBuilder))
    return;

  DisplayOutlineUnconditional(aBuilder, aLists);
}

void
nsIFrame::DisplayCaret(nsDisplayListBuilder* aBuilder,
                       const nsRect& aDirtyRect, nsDisplayList* aList)
{
  if (!IsVisibleForPainting(aBuilder))
    return;

  aList->AppendNewToTop(new (aBuilder) nsDisplayCaret(aBuilder, this));
}

nscolor
nsIFrame::GetCaretColorAt(int32_t aOffset)
{
  return nsLayoutUtils::GetColor(this, &nsStyleUserInterface::mCaretColor);
}

bool
nsFrame::DisplayBackgroundUnconditional(nsDisplayListBuilder* aBuilder,
                                        const nsDisplayListSet& aLists,
                                        bool aForceBackground)
{
  // Here we don't try to detect background propagation. Frames that might
  // receive a propagated background should just set aForceBackground to
  // true.
  if (aBuilder->IsForEventDelivery() || aForceBackground ||
      !StyleBackground()->IsTransparent(this) || StyleDisplay()->mAppearance) {
    return nsDisplayBackgroundImage::AppendBackgroundItemsToTop(
        aBuilder, this, GetRectRelativeToSelf(), aLists.BorderBackground());
  }
  return false;
}

void
nsFrame::DisplayBorderBackgroundOutline(nsDisplayListBuilder*   aBuilder,
                                        const nsDisplayListSet& aLists,
                                        bool                    aForceBackground)
{
  // The visibility check belongs here since child elements have the
  // opportunity to override the visibility property and display even if
  // their parent is hidden.
  if (!IsVisibleForPainting(aBuilder)) {
    return;
  }

  nsCSSShadowArray* shadows = StyleEffects()->mBoxShadow;
  if (shadows && shadows->HasShadowWithInset(false)) {
    aLists.BorderBackground()->AppendNewToTop(new (aBuilder)
      nsDisplayBoxShadowOuter(aBuilder, this));
  }

  bool bgIsThemed = DisplayBackgroundUnconditional(aBuilder, aLists,
                                                   aForceBackground);

  if (shadows && shadows->HasShadowWithInset(true)) {
    aLists.BorderBackground()->AppendNewToTop(new (aBuilder)
      nsDisplayBoxShadowInner(aBuilder, this));
  }

  // If there's a themed background, we should not create a border item.
  // It won't be rendered.
  if (!bgIsThemed && StyleBorder()->HasBorder()) {
    aLists.BorderBackground()->AppendNewToTop(new (aBuilder)
      nsDisplayBorder(aBuilder, this));
  }

  DisplayOutlineUnconditional(aBuilder, aLists);
}

inline static bool IsSVGContentWithCSSClip(const nsIFrame *aFrame)
{
  // The CSS spec says that the 'clip' property only applies to absolutely
  // positioned elements, whereas the SVG spec says that it applies to SVG
  // elements regardless of the value of the 'position' property. Here we obey
  // the CSS spec for outer-<svg> (since that's what we generally do), but
  // obey the SVG spec for other SVG elements to which 'clip' applies.
  return (aFrame->GetStateBits() & NS_FRAME_SVG_LAYOUT) &&
          aFrame->GetContent()->IsAnyOfSVGElements(nsGkAtoms::svg,
                                                   nsGkAtoms::foreignObject);
}

Maybe<nsRect>
nsIFrame::GetClipPropClipRect(const nsStyleDisplay* aDisp,
                              const nsStyleEffects* aEffects,
                              const nsSize& aSize) const
{
  if (!(aEffects->mClipFlags & NS_STYLE_CLIP_RECT) ||
      !(aDisp->IsAbsolutelyPositioned(this) || IsSVGContentWithCSSClip(this))) {
    return Nothing();
  }

  nsRect rect = aEffects->mClip;
  if (MOZ_LIKELY(StyleBorder()->mBoxDecorationBreak ==
                   StyleBoxDecorationBreak::Slice)) {
    // The clip applies to the joined boxes so it's relative the first
    // continuation.
    nscoord y = 0;
    for (nsIFrame* f = GetPrevContinuation(); f; f = f->GetPrevContinuation()) {
      y += f->GetRect().height;
    }
    rect.MoveBy(nsPoint(0, -y));
  }

  if (NS_STYLE_CLIP_RIGHT_AUTO & aEffects->mClipFlags) {
    rect.width = aSize.width - rect.x;
  }
  if (NS_STYLE_CLIP_BOTTOM_AUTO & aEffects->mClipFlags) {
    rect.height = aSize.height - rect.y;
  }
  return Some(rect);
}

/**
 * If the CSS 'overflow' property applies to this frame, and is not
 * handled by constructing a dedicated nsHTML/XULScrollFrame, set up clipping
 * for that overflow in aBuilder->ClipState() to clip all containing-block
 * descendants.
 *
 * Return true if clipping was applied.
 */
static bool
ApplyOverflowClipping(nsDisplayListBuilder* aBuilder,
                      const nsIFrame* aFrame,
                      const nsStyleDisplay* aDisp,
                      DisplayListClipState::AutoClipMultiple& aClipState)
{
  // Only -moz-hidden-unscrollable is handled here (and 'hidden' for table
  // frames, and any non-visible value for blocks in a paginated context).
  // We allow -moz-hidden-unscrollable to apply to any kind of frame. This
  // is required by comboboxes which make their display text (an inline frame)
  // have clipping.
  if (!nsFrame::ShouldApplyOverflowClipping(aFrame, aDisp)) {
    return false;
  }
  nsRect clipRect;
  bool haveRadii = false;
  nscoord radii[8];
  if (aFrame->StyleDisplay()->mOverflowClipBox ==
        NS_STYLE_OVERFLOW_CLIP_BOX_PADDING_BOX) {
    clipRect = aFrame->GetPaddingRectRelativeToSelf() +
      aBuilder->ToReferenceFrame(aFrame);
    haveRadii = aFrame->GetPaddingBoxBorderRadii(radii);
  } else {
    clipRect = aFrame->GetContentRectRelativeToSelf() +
      aBuilder->ToReferenceFrame(aFrame);
    // XXX border-radius
  }
  aClipState.ClipContainingBlockDescendantsExtra(clipRect, haveRadii ? radii : nullptr);
  return true;
}

#ifdef DEBUG
static void PaintDebugBorder(nsIFrame* aFrame, DrawTarget* aDrawTarget,
     const nsRect& aDirtyRect, nsPoint aPt)
{
  nsRect r(aPt, aFrame->GetSize());
  int32_t appUnitsPerDevPixel = aFrame->PresContext()->AppUnitsPerDevPixel();
  Color blueOrRed(aFrame->HasView() ? Color(0.f, 0.f, 1.f, 1.f) :
                                      Color(1.f, 0.f, 0.f, 1.f));
  aDrawTarget->StrokeRect(NSRectToRect(r, appUnitsPerDevPixel),
                          ColorPattern(ToDeviceColor(blueOrRed)));
}

static void PaintEventTargetBorder(nsIFrame* aFrame, DrawTarget* aDrawTarget,
     const nsRect& aDirtyRect, nsPoint aPt)
{
  nsRect r(aPt, aFrame->GetSize());
  int32_t appUnitsPerDevPixel = aFrame->PresContext()->AppUnitsPerDevPixel();
  ColorPattern purple(ToDeviceColor(Color(.5f, 0.f, .5f, 1.f)));
  aDrawTarget->StrokeRect(NSRectToRect(r, appUnitsPerDevPixel), purple);
}

static void
DisplayDebugBorders(nsDisplayListBuilder* aBuilder, nsIFrame* aFrame,
                    const nsDisplayListSet& aLists) {
  // Draw a border around the child
  // REVIEW: From nsContainerFrame::PaintChild
  if (nsFrame::GetShowFrameBorders() && !aFrame->GetRect().IsEmpty()) {
    aLists.Outlines()->AppendNewToTop(new (aBuilder)
        nsDisplayGeneric(aBuilder, aFrame, PaintDebugBorder, "DebugBorder",
                         nsDisplayItem::TYPE_DEBUG_BORDER));
  }
  // Draw a border around the current event target
  if (nsFrame::GetShowEventTargetFrameBorder() &&
      aFrame->PresContext()->PresShell()->GetDrawEventTargetFrame() == aFrame) {
    aLists.Outlines()->AppendNewToTop(new (aBuilder)
        nsDisplayGeneric(aBuilder, aFrame, PaintEventTargetBorder, "EventTargetBorder",
                         nsDisplayItem::TYPE_EVENT_TARGET_BORDER));
  }
}
#endif

static bool
IsScrollFrameActive(nsDisplayListBuilder* aBuilder, nsIScrollableFrame* aScrollableFrame)
{
  return aScrollableFrame && aScrollableFrame->IsScrollingActive(aBuilder);
}

/**
 * Returns whether a display item that gets created with the builder's current
 * state will have a scrolled clip, i.e. a clip that is scrolled by a scroll
 * frame which does not move the item itself.
 */
static bool
BuilderHasScrolledClip(nsDisplayListBuilder* aBuilder)
{
  const DisplayItemClipChain* currentClip =
    aBuilder->ClipState().GetCurrentCombinedClipChain(aBuilder);
  if (!currentClip) {
    return false;
  }

  const ActiveScrolledRoot* currentClipASR = currentClip->mASR;
  const ActiveScrolledRoot* currentASR = aBuilder->CurrentActiveScrolledRoot();
  return ActiveScrolledRoot::PickDescendant(currentClipASR, currentASR) != currentASR;
}

class AutoSaveRestoreContainsBlendMode
{
  nsDisplayListBuilder& mBuilder;
  bool mSavedContainsBlendMode;
public:
  explicit AutoSaveRestoreContainsBlendMode(nsDisplayListBuilder& aBuilder)
    : mBuilder(aBuilder)
    , mSavedContainsBlendMode(aBuilder.ContainsBlendMode())
  { }

  ~AutoSaveRestoreContainsBlendMode() {
    mBuilder.SetContainsBlendMode(mSavedContainsBlendMode);
  }
};

static void
CheckForApzAwareEventHandlers(nsDisplayListBuilder* aBuilder, nsIFrame* aFrame)
{
  nsIContent* content = aFrame->GetContent();
  if (!content) {
    return;
  }

  if (content->IsNodeApzAware()) {
    aBuilder->SetAncestorHasApzAwareEventHandler(true);
  }
}

/**
 * True if aDescendant participates the context aAncestor participating.
 */
static bool
FrameParticipatesIn3DContext(nsIFrame* aAncestor, nsIFrame* aDescendant) {
  MOZ_ASSERT(aAncestor != aDescendant);
  MOZ_ASSERT(aAncestor->Extend3DContext());
  nsIFrame* frame;
  for (frame = aDescendant->GetFlattenedTreeParentPrimaryFrame();
       frame && aAncestor != frame;
       frame = frame->GetFlattenedTreeParentPrimaryFrame()) {
    if (!frame->Extend3DContext()) {
      return false;
    }
  }
  MOZ_ASSERT(frame == aAncestor);
  return true;
}

static bool
ItemParticipatesIn3DContext(nsIFrame* aAncestor, nsDisplayItem* aItem)
{
  nsIFrame* transformFrame;
  if (aItem->GetType() == nsDisplayItem::TYPE_TRANSFORM) {
    transformFrame = aItem->Frame();
  } else if (aItem->GetType() == nsDisplayItem::TYPE_PERSPECTIVE) {
    transformFrame = static_cast<nsDisplayPerspective*>(aItem)->TransformFrame();
  } else {
    return false;
  }
  if (aAncestor == transformFrame) {
    return true;
  }
  return FrameParticipatesIn3DContext(aAncestor, transformFrame);
}

static void
WrapSeparatorTransform(nsDisplayListBuilder* aBuilder, nsIFrame* aFrame,
                       nsRect& aDirtyRect,
                       nsDisplayList* aSource, nsDisplayList* aTarget,
                       int aIndex) {
  if (!aSource->IsEmpty()) {
    nsDisplayTransform *sepIdItem =
      new (aBuilder) nsDisplayTransform(aBuilder, aFrame, aSource,
                                        aDirtyRect, Matrix4x4(), aIndex);
    sepIdItem->SetNoExtendContext();
    aTarget->AppendToTop(sepIdItem);
  }
}

void
nsIFrame::BuildDisplayListForStackingContext(nsDisplayListBuilder* aBuilder,
                                             const nsRect&         aDirtyRect,
                                             nsDisplayList*        aList) {
  if (GetStateBits() & NS_FRAME_TOO_DEEP_IN_FRAME_TREE)
    return;

  // Replaced elements have their visibility handled here, because
  // they're visually atomic
  if (IsFrameOfType(eReplaced) && !IsVisibleForPainting(aBuilder))
    return;

  const nsStyleDisplay* disp = StyleDisplay();
  const nsStyleEffects* effects = StyleEffects();
  EffectSet* effectSet = EffectSet::GetEffectSet(this);
  // We can stop right away if this is a zero-opacity stacking context and
  // we're painting, and we're not animating opacity. Don't do this
  // if we're going to compute plugin geometry, since opacity-0 plugins
  // need to have display items built for them.
  bool needEventRegions =
    aBuilder->IsBuildingLayerEventRegions() &&
    StyleUserInterface()->GetEffectivePointerEvents(this) !=
      NS_STYLE_POINTER_EVENTS_NONE;
  bool opacityItemForEventsAndPluginsOnly = false;
  if (effects->mOpacity == 0.0 && aBuilder->IsForPainting() &&
      !(disp->mWillChangeBitField & NS_STYLE_WILL_CHANGE_OPACITY) &&
      !nsLayoutUtils::HasAnimationOfProperty(effectSet, eCSSProperty_opacity)) {
    if (needEventRegions ||
        aBuilder->WillComputePluginGeometry()) {
      opacityItemForEventsAndPluginsOnly = true;
    } else {
      return;
    }
  }

  if (disp->mWillChangeBitField != 0) {
    aBuilder->AddToWillChangeBudget(this, GetSize());
  }

  bool extend3DContext = Extend3DContext(disp, effectSet);
  Maybe<nsDisplayListBuilder::AutoPreserves3DContext> autoPreserves3DContext;
  if (extend3DContext && !Combines3DTransformWithAncestors(disp)) {
    // Start a new preserves3d context to keep informations on
    // nsDisplayListBuilder.
    autoPreserves3DContext.emplace(aBuilder);
    // Save dirty rect on the builder to avoid being distorted for
    // multiple transforms along the chain.
    aBuilder->SetPreserves3DDirtyRect(aDirtyRect);
  }

  // For preserves3d, use the dirty rect already installed on the
  // builder, since aDirtyRect maybe distorted for transforms along
  // the chain.
  nsRect dirtyRect = aDirtyRect;

  bool inTransform = aBuilder->IsInTransform();
  bool isTransformed = IsTransformed(disp, effectSet);
  bool hasPerspective = HasPerspective(effectSet);
  // reset blend mode so we can keep track if this stacking context needs have
  // a nsDisplayBlendContainer. Set the blend mode back when the routine exits
  // so we keep track if the parent stacking context needs a container too.
  AutoSaveRestoreContainsBlendMode autoRestoreBlendMode(*aBuilder);
  aBuilder->SetContainsBlendMode(false);
 
  nsRect dirtyRectOutsideTransform = dirtyRect;
  bool allowAsyncAnimation = false;
  if (isTransformed) {
    const nsRect overflow = GetVisualOverflowRectRelativeToSelf();
    nsDisplayTransform::PrerenderDecision decision =
        nsDisplayTransform::ShouldPrerenderTransformedContent(aBuilder, this, &dirtyRect);
    switch (decision) {
    case nsDisplayTransform::FullPrerender:
      allowAsyncAnimation = true;
      break;
    case nsDisplayTransform::PartialPrerender:
      allowAsyncAnimation = true;
      MOZ_FALLTHROUGH;
      // fall through to the NoPrerender case
    case nsDisplayTransform::NoPrerender:
      if (overflow.IsEmpty() && !extend3DContext) {
        return;
      }

      // If we're in preserve-3d then grab the dirty rect that was given to the root
      // and transform using the combined transform.
      if (Combines3DTransformWithAncestors(disp)) {
        dirtyRect = aBuilder->GetPreserves3DDirtyRect(this);
      }

      nsRect untransformedDirtyRect;
      if (nsDisplayTransform::UntransformRect(dirtyRect, overflow, this,
            &untransformedDirtyRect)) {
        dirtyRect = untransformedDirtyRect;
      } else {
        NS_WARNING("Unable to untransform dirty rect!");
        // This should only happen if the transform is singular, in which case nothing is visible anyway
        dirtyRect.SetEmpty();
      }
    }
    inTransform = true;
  }
  bool usingFilter = StyleEffects()->HasFilters();
  bool usingMask = nsSVGIntegrationUtils::UsingMaskOrClipPathForFrame(this);
  bool usingSVGEffects = usingFilter || usingMask;

  nsRect dirtyRectOutsideSVGEffects = dirtyRect;
  nsDisplayList hoistedScrollInfoItemsStorage;
  if (usingSVGEffects) {
    dirtyRect =
      nsSVGIntegrationUtils::GetRequiredSourceForInvalidArea(this, dirtyRect);
    aBuilder->EnterSVGEffectsContents(&hoistedScrollInfoItemsStorage);
  }

  // We build an opacity item if it's not going to be drawn by SVG content, or
  // SVG effects. SVG effects won't handle the opacity if we want an active
  // layer (for async animations), see
  // nsSVGIntegrationsUtils::PaintMaskAndClipPath or
  // nsSVGIntegrationsUtils::PaintFilter.
  bool useOpacity = HasVisualOpacity(effectSet) &&
                    !nsSVGUtils::CanOptimizeOpacity(this) &&
                    (!usingSVGEffects || nsDisplayOpacity::NeedsActiveLayer(aBuilder, this));
  bool useBlendMode = effects->mMixBlendMode != NS_STYLE_BLEND_NORMAL;
  bool useStickyPosition = disp->mPosition == NS_STYLE_POSITION_STICKY &&
    IsScrollFrameActive(aBuilder,
                        nsLayoutUtils::GetNearestScrollableFrame(GetParent(),
                        nsLayoutUtils::SCROLLABLE_SAME_DOC |
                        nsLayoutUtils::SCROLLABLE_INCLUDE_HIDDEN));
  bool useFixedPosition = disp->mPosition == NS_STYLE_POSITION_FIXED &&
    (nsLayoutUtils::IsFixedPosFrameInDisplayPort(this) || BuilderHasScrolledClip(aBuilder));

  nsDisplayListBuilder::AutoBuildingDisplayList
    buildingDisplayList(aBuilder, this, dirtyRect, true);

  // Depending on the effects that are applied to this frame, we can create
  // multiple container display items and wrap them around our contents.
  // This enum lists all the potential container display items, in the order
  // outside to inside.
  enum class ContainerItemType : uint8_t {
    eNone = 0,
    eOwnLayerIfNeeded,
    eBlendMode,
    eFixedPosition,
    eOwnLayerForTransformWithRoundedClip,
    ePerspective,
    eTransform,
    eSeparatorTransforms,
    eOpacity,
    eFilter,
    eBlendContainer
  };

  nsDisplayListBuilder::AutoContainerASRTracker contASRTracker(aBuilder);

  DisplayListClipState::AutoSaveRestore clipState(aBuilder);

  // If there is a current clip, then depending on the container items we
  // create, different things can happen to it. Some container items simply
  // propagate the clip to their children and aren't clipped themselves.
  // But other container items, especially those that establish a different
  // geometry for their contents (e.g. transforms), capture the clip on
  // themselves and unset the clip for their contents. If we create more than
  // one of those container items, the clip will be captured on the outermost
  // one and the inner container items will be unclipped.
  ContainerItemType clipCapturedBy = ContainerItemType::eNone;
  if (useFixedPosition) {
    clipCapturedBy = ContainerItemType::eFixedPosition;
  } else if (isTransformed) {
    const DisplayItemClipChain* currentClip =
      aBuilder->ClipState().GetCurrentCombinedClipChain(aBuilder);
    if ((hasPerspective || extend3DContext) &&
        (currentClip && currentClip->HasRoundedCorners())) {
      // If we're creating an nsDisplayTransform item that is going to combine
      // its transform with its children (preserve-3d or perspective), then we
      // can't have an intermediate surface. Mask layers force an intermediate
      // surface, so if we're going to need both then create a separate
      // wrapping layer for the mask.
      clipCapturedBy = ContainerItemType::eOwnLayerForTransformWithRoundedClip;
    } else if (hasPerspective) {
      clipCapturedBy = ContainerItemType::ePerspective;
    } else {
      clipCapturedBy = ContainerItemType::eTransform;
    }
  } else if (usingFilter) {
    clipCapturedBy = ContainerItemType::eFilter;
  }

  if (clipCapturedBy != ContainerItemType::eNone) {
    clipState.Clear();
  }

  nsDisplayListCollection set;
  {
    DisplayListClipState::AutoSaveRestore nestedClipState(aBuilder);
    nsDisplayListBuilder::AutoInTransformSetter
      inTransformSetter(aBuilder, inTransform);
    nsDisplayListBuilder::AutoSaveRestorePerspectiveIndex
      perspectiveIndex(aBuilder, this);

    CheckForApzAwareEventHandlers(aBuilder, this);

    Maybe<nsRect> contentClip =
      GetClipPropClipRect(disp, effects, GetSize());

    if (contentClip) {
      dirtyRect.IntersectRect(dirtyRect, *contentClip);
      nestedClipState.ClipContentDescendants(*contentClip +
                                             aBuilder->ToReferenceFrame(this));
    }

    // extend3DContext also guarantees that applyAbsPosClipping and usingSVGEffects are false
    // We only modify the preserve-3d rect if we are the top of a preserve-3d heirarchy
    if (extend3DContext) {
      // Mark these first so MarkAbsoluteFramesForDisplayList knows if we are
      // going to be forced to descend into frames.
      aBuilder->MarkPreserve3DFramesForDisplayList(this);
    }

    MarkAbsoluteFramesForDisplayList(aBuilder, dirtyRect);

    nsDisplayLayerEventRegions* eventRegions = nullptr;
    if (aBuilder->IsBuildingLayerEventRegions()) {
      eventRegions = new (aBuilder) nsDisplayLayerEventRegions(aBuilder, this);
      eventRegions->AddFrame(aBuilder, this);
      aBuilder->SetLayerEventRegions(eventRegions);
    }
    aBuilder->AdjustWindowDraggingRegion(this);
    BuildDisplayList(aBuilder, dirtyRect, set);
    if (eventRegions) {
      // If the event regions item ended up empty, throw it away rather than
      // adding it to the display list.
      if (!eventRegions->IsEmpty()) {
        set.BorderBackground()->AppendToBottom(eventRegions);
      } else {
        aBuilder->SetLayerEventRegions(nullptr);
        eventRegions->~nsDisplayLayerEventRegions();
        eventRegions = nullptr;
      }
    }
  }

  if (aBuilder->IsBackgroundOnly()) {
    set.BlockBorderBackgrounds()->DeleteAll();
    set.Floats()->DeleteAll();
    set.Content()->DeleteAll();
    set.PositionedDescendants()->DeleteAll();
    set.Outlines()->DeleteAll();
  }

  // Sort PositionedDescendants() in CSS 'z-order' order.  The list is already
  // in content document order and SortByZOrder is a stable sort which
  // guarantees that boxes produced by the same element are placed together
  // in the sort. Consider a position:relative inline element that breaks
  // across lines and has absolutely positioned children; all the abs-pos
  // children should be z-ordered after all the boxes for the position:relative
  // element itself.
  set.PositionedDescendants()->SortByZOrder();

  nsDisplayList resultList;
  // Now follow the rules of http://www.w3.org/TR/CSS21/zindex.html
  // 1,2: backgrounds and borders
  resultList.AppendToTop(set.BorderBackground());
  // 3: negative z-index children.
  for (;;) {
    nsDisplayItem* item = set.PositionedDescendants()->GetBottom();
    if (item && item->ZIndex() < 0) {
      set.PositionedDescendants()->RemoveBottom();
      resultList.AppendToTop(item);
      continue;
    }
    break;
  }
  // 4: block backgrounds
  resultList.AppendToTop(set.BlockBorderBackgrounds());
  // 5: floats
  resultList.AppendToTop(set.Floats());
  // 7: general content
  resultList.AppendToTop(set.Content());
  // 7.5: outlines, in content tree order. We need to sort by content order
  // because an element with outline that breaks and has children with outline
  // might have placed child outline items between its own outline items.
  // The element's outline items need to all come before any child outline
  // items.
  nsIContent* content = GetContent();
  if (!content) {
    content = PresContext()->Document()->GetRootElement();
  }
  if (content) {
    set.Outlines()->SortByContentOrder(content);
  }
#ifdef DEBUG
  DisplayDebugBorders(aBuilder, this, set);
#endif
  resultList.AppendToTop(set.Outlines());
  // 8, 9: non-negative z-index children
  resultList.AppendToTop(set.PositionedDescendants());

  // Get the ASR to use for the container items that we create here.
  const ActiveScrolledRoot* containerItemASR = contASRTracker.GetContainerASR();

  /* If adding both a nsDisplayBlendContainer and a nsDisplayBlendMode to the
   * same list, the nsDisplayBlendContainer should be added first. This only
   * happens when the element creating this stacking context has mix-blend-mode
   * and also contains a child which has mix-blend-mode.
   * The nsDisplayBlendContainer must be added to the list first, so it does not
   * isolate the containing element blending as well.
   */
  if (aBuilder->ContainsBlendMode()) {
    DisplayListClipState::AutoSaveRestore blendContainerClipState(aBuilder);
    blendContainerClipState.ClearUpToASR(containerItemASR);
    resultList.AppendNewToTop(
      nsDisplayBlendContainer::CreateForMixBlendMode(aBuilder, this, &resultList,
                                                     containerItemASR));
  }

  /* If there are any SVG effects, wrap the list up in an SVG effects item
   * (which also handles CSS group opacity). Note that we create an SVG effects
   * item even if resultList is empty, since a filter can produce graphical
   * output even if the element being filtered wouldn't otherwise do so.
   */
  if (usingSVGEffects) {
    MOZ_ASSERT(usingFilter ||usingMask,
               "Beside filter & mask/clip-path, what else effect do we have?");

    if (clipCapturedBy == ContainerItemType::eFilter) {
      clipState.Restore();
    }
    // Revert to the post-filter dirty rect.
    buildingDisplayList.SetDirtyRect(dirtyRectOutsideSVGEffects);

    // Skip all filter effects while generating glyph mask.
    if (usingFilter && !aBuilder->IsForGenerateGlyphMask()) {
      // If we are going to create a mask display item, handle opacity effect
      // in that mask display item; Otherwise, take care of opacity in this
      // filter display item.
      bool handleOpacity = !usingMask && !useOpacity;

      /* List now emptied, so add the new list to the top. */
      resultList.AppendNewToTop(
        new (aBuilder) nsDisplayFilter(aBuilder, this, &resultList,
                                       handleOpacity));
    }

    if (usingMask) {
      DisplayListClipState::AutoSaveRestore maskClipState(aBuilder);
      maskClipState.ClearUpToASR(containerItemASR);
      /* List now emptied, so add the new list to the top. */
      resultList.AppendNewToTop(
          new (aBuilder) nsDisplayMask(aBuilder, this, &resultList,
                                       !useOpacity, containerItemASR));
    }

    // Also add the hoisted scroll info items. We need those for APZ scrolling
    // because nsDisplayMask items can't build active layers.
    aBuilder->ExitSVGEffectsContents();
    resultList.AppendToTop(&hoistedScrollInfoItemsStorage);
  }

  /* If the list is non-empty and there is CSS group opacity without SVG
   * effects, wrap it up in an opacity item.
   */
  if (useOpacity && !resultList.IsEmpty()) {
    // Don't clip nsDisplayOpacity items. We clip their descendants instead.
    // The clip we would set on an element with opacity would clip
    // all descendant content, but some should not be clipped.
    DisplayListClipState::AutoSaveRestore opacityClipState(aBuilder);
    opacityClipState.ClearUpToASR(containerItemASR);
    resultList.AppendNewToTop(
        new (aBuilder) nsDisplayOpacity(aBuilder, this, &resultList,
                                        containerItemASR,
                                        opacityItemForEventsAndPluginsOnly));
  }

  /* If we're going to apply a transformation and don't have preserve-3d set, wrap
   * everything in an nsDisplayTransform. If there's nothing in the list, don't add
   * anything.
   *
   * For the preserve-3d case we want to individually wrap every child in the list with
   * a separate nsDisplayTransform instead. When the child is already an nsDisplayTransform,
   * we can skip this step, as the computed transform will already include our own.
   *
   * We also traverse into sublists created by nsDisplayWrapList, so that we find all the
   * correct children.
   */
  if (isTransformed && !resultList.IsEmpty() && extend3DContext) {
    // Install dummy nsDisplayTransform as a leaf containing
    // descendants not participating this 3D rendering context.
    nsDisplayList nonparticipants;
    nsDisplayList participants;
    int index = 1;

    while (nsDisplayItem* item = resultList.RemoveBottom()) {
      if (ItemParticipatesIn3DContext(this, item) && !item->GetClip().HasClip()) {
        // The frame of this item participates the same 3D context.
        WrapSeparatorTransform(aBuilder, this, dirtyRect,
                               &nonparticipants, &participants, index++);
        participants.AppendToTop(item);
      } else {
        // The frame of the item doesn't participate the current
        // context, or has no transform.
        //
        // For items participating but not transformed, they are add
        // to nonparticipants to get a separator layer for handling
        // clips, if there is, on an intermediate surface.
        // \see ContainerLayer::DefaultComputeEffectiveTransforms().
        nonparticipants.AppendToTop(item);
      }
    }
    WrapSeparatorTransform(aBuilder, this, dirtyRect,
                           &nonparticipants, &participants, index++);
    resultList.AppendToTop(&participants);
  }

  if (isTransformed && !resultList.IsEmpty()) {
    if (clipCapturedBy == ContainerItemType::eTransform) {
      // Restore clip state now so nsDisplayTransform is clipped properly.
      clipState.Restore();
    }
    // Revert to the dirtyrect coming in from the parent, without our transform
    // taken into account.
    buildingDisplayList.SetDirtyRect(dirtyRectOutsideTransform);
    // Revert to the outer reference frame and offset because all display
    // items we create from now on are outside the transform.
    nsPoint toOuterReferenceFrame;
    const nsIFrame* outerReferenceFrame = this;
    if (this != aBuilder->RootReferenceFrame()) {
      outerReferenceFrame =
        aBuilder->FindReferenceFrameFor(GetParent(), &toOuterReferenceFrame);
    }
    buildingDisplayList.SetReferenceFrameAndCurrentOffset(outerReferenceFrame,
      GetOffsetToCrossDoc(outerReferenceFrame));

    if (!aBuilder->IsForGenerateGlyphMask() &&
        !aBuilder->IsForPaintingSelectionBG()) {
      nsDisplayTransform *transformItem =
        new (aBuilder) nsDisplayTransform(aBuilder, this,
                                          &resultList, dirtyRect, 0,
                                          allowAsyncAnimation);
      resultList.AppendNewToTop(transformItem);
    }

    if (hasPerspective) {
      if (clipCapturedBy == ContainerItemType::ePerspective) {
        clipState.Restore();
      }
      resultList.AppendNewToTop(
        new (aBuilder) nsDisplayPerspective(
          aBuilder, this,
          GetContainingBlock(0, disp)->GetContent()->GetPrimaryFrame(),
          &resultList));
    }
  }

  if (clipCapturedBy == ContainerItemType::eOwnLayerForTransformWithRoundedClip) {
    clipState.Restore();
    resultList.AppendNewToTop(
      new (aBuilder) nsDisplayOwnLayer(aBuilder, this, &resultList,
                                       aBuilder->CurrentActiveScrolledRoot(), 0,
                                       mozilla::layers::FrameMetrics::NULL_SCROLL_ID,
                                       ScrollThumbData{}, /* aForceActive = */ false));
  }

  /* If we have sticky positioning, wrap it in a sticky position item.
   */
  if (useFixedPosition) {
    if (clipCapturedBy == ContainerItemType::eFixedPosition) {
      clipState.Restore();
    }
    // The ASR for the fixed item should be the ASR of our containing block,
    // which has been set as the builder's current ASR, unless this frame is
    // invisible and we hadn't saved display item data for it. In that case,
    // we need to take the containerItemASR since we might have fixed children.
    const ActiveScrolledRoot* fixedASR =
      ActiveScrolledRoot::PickAncestor(containerItemASR, aBuilder->CurrentActiveScrolledRoot());
    resultList.AppendNewToTop(
        new (aBuilder) nsDisplayFixedPosition(aBuilder, this, &resultList, fixedASR));
  } else if (useStickyPosition) {
    // For position:sticky, the clip needs to be applied both to the sticky
    // container item and to the contents. The container item needs the clip
    // because a scrolled clip needs to move independently from the sticky
    // contents, and the contents need the clip so that they have finite
    // clipped bounds with respect to the container item's ASR. The latter is
    // a little tricky in the case where the sticky item has both fixed and
    // non-fixed descendants, because that means that the sticky container
    // item's ASR is the ASR of the fixed descendant.
    const ActiveScrolledRoot* stickyASR =
      ActiveScrolledRoot::PickAncestor(containerItemASR, aBuilder->CurrentActiveScrolledRoot());
    resultList.AppendNewToTop(
        new (aBuilder) nsDisplayStickyPosition(aBuilder, this, &resultList, stickyASR));
  }

  /* If there's blending, wrap up the list in a blend-mode item. Note
   * that opacity can be applied before blending as the blend color is
   * not affected by foreground opacity (only background alpha).
   */

  if (useBlendMode && !resultList.IsEmpty()) {
    DisplayListClipState::AutoSaveRestore blendModeClipState(aBuilder);
    blendModeClipState.ClearUpToASR(containerItemASR);
    resultList.AppendNewToTop(
        new (aBuilder) nsDisplayBlendMode(aBuilder, this, &resultList,
                                          effects->mMixBlendMode,
                                          containerItemASR));
  }

  CreateOwnLayerIfNeeded(aBuilder, &resultList);

  aList->AppendToTop(&resultList);
}

static nsDisplayItem*
WrapInWrapList(nsDisplayListBuilder* aBuilder,
               nsIFrame* aFrame, nsDisplayList* aList,
               const ActiveScrolledRoot* aContainerASR)
{
  nsDisplayItem* item = aList->GetBottom();
  if (!item) {
    return nullptr;
  }

  // For perspective items we want to treat the 'frame' as being the transform
  // frame that created it. This stops the transform frame from wrapping another
  // nsDisplayWrapList around it (with mismatching reference frames), but still
  // makes the perspective frame create one (so we have an atomic entry for z-index
  // sorting).
  nsIFrame *itemFrame = item->Frame();
  if (item->GetType() == nsDisplayItem::TYPE_PERSPECTIVE) {
    itemFrame = static_cast<nsDisplayPerspective*>(item)->TransformFrame();
  }

  if (item->GetAbove() || itemFrame != aFrame) {
    return new (aBuilder) nsDisplayWrapList(aBuilder, aFrame, aList, aContainerASR);
  }
  aList->RemoveBottom();
  return item;
}

/**
 * Check if a frame should be visited for building display list.
 */
static bool
DescendIntoChild(nsDisplayListBuilder* aBuilder, nsIFrame *aChild,
                 const nsRect& aDirty)
{
  nsIFrame* child = aChild;
  const nsRect& dirty = aDirty;

  if (!(child->GetStateBits() & NS_FRAME_FORCE_DISPLAY_LIST_DESCEND_INTO)) {
    // No need to descend into child to catch placeholders for visible
    // positioned stuff. So see if we can short-circuit frame traversal here.

    // We can stop if child's frame subtree's intersection with the
    // dirty area is empty.
    // If the child is a scrollframe that we want to ignore, then we need
    // to descend into it because its scrolled child may intersect the dirty
    // area even if the scrollframe itself doesn't.
    // There are cases where the "ignore scroll frame" on the builder is not set
    // correctly, and so we additionally want to catch cases where the child is
    // a root scrollframe and we are ignoring scrolling on the viewport.
    nsIPresShell* shell = child->PresContext()->PresShell();
    bool keepDescending = child == aBuilder->GetIgnoreScrollFrame() ||
      (shell->IgnoringViewportScrolling() && child == shell->GetRootScrollFrame());
    if (!keepDescending) {
      nsRect childDirty;
      if (!childDirty.IntersectRect(dirty, child->GetVisualOverflowRect()))
        return false;
      // Usually we could set dirty to childDirty now but there's no
      // benefit, and it can be confusing. It can especially confuse
      // situations where we're going to ignore a scrollframe's clipping;
      // we wouldn't want to clip the dirty area to the scrollframe's
      // bounds in that case.
    }
  }
  return true;
}

void
nsIFrame::BuildDisplayListForChild(nsDisplayListBuilder*   aBuilder,
                                   nsIFrame*               aChild,
                                   const nsRect&           aDirtyRect,
                                   const nsDisplayListSet& aLists,
                                   uint32_t                aFlags) {
  // If painting is restricted to just the background of the top level frame,
  // then we have nothing to do here.
  if (aBuilder->IsBackgroundOnly())
    return;

  if (aBuilder->IsForGenerateGlyphMask() ||
      aBuilder->IsForPaintingSelectionBG()) {
    if (!aChild->IsTextFrame() && aChild->IsLeaf()) {
      return;
    }
  }

  nsIFrame* child = aChild;
  if (child->GetStateBits() & NS_FRAME_TOO_DEEP_IN_FRAME_TREE)
    return;

  const bool doingShortcut =
    (child->GetStateBits() & NS_FRAME_SIMPLE_DISPLAYLIST) &&
    aBuilder->IsPaintingToWindow() &&
    // This would be changed by the change of preference.
    aBuilder->IsBuildingLayerEventRegions() &&
    // Animations may change the value of |HasOpacity()|.
    !(child->GetContent() &&
      child->GetContent()->MayHaveAnimations());
  if (doingShortcut) {
    // This is the shortcut for frames been handled along the common
    // path, the most common one of THE COMMON CASE mentioned later.
    MOZ_ASSERT(child->Type() != LayoutFrameType::Placeholder);
    MOZ_ASSERT(!aBuilder->GetSelectedFramesOnly() &&
               !aBuilder->GetIncludeAllOutOfFlows(),
               "It should be held for painting to window");

    // dirty rect in child-relative coordinates
    nsRect dirty = aDirtyRect - child->GetOffsetTo(this);
    if (!DescendIntoChild(aBuilder, child, dirty)) {
      return;
    }

    nsDisplayListBuilder::AutoBuildingDisplayList
      buildingForChild(aBuilder, child, dirty, false);

    CheckForApzAwareEventHandlers(aBuilder, child);

    nsDisplayLayerEventRegions* eventRegions = aBuilder->GetLayerEventRegions();
    if (eventRegions) {
      eventRegions->AddFrame(aBuilder, child);
    }

    child->MarkAbsoluteFramesForDisplayList(aBuilder, dirty);
    aBuilder->AdjustWindowDraggingRegion(child);
    child->BuildDisplayList(aBuilder, dirty, aLists);
    aBuilder->DisplayCaret(child, dirty, aLists.Content());
#ifdef DEBUG
    DisplayDebugBorders(aBuilder, child, aLists);
#endif
    return;
  }

  bool isSVG = (child->GetStateBits() & NS_FRAME_SVG_LAYOUT);

  // It is raised if the control flow strays off the common path.
  // The common path is the most common one of THE COMMON CASE
  // mentioned later.
  bool awayFromCommonPath = false;

  // true if this is a real or pseudo stacking context
  bool pseudoStackingContext =
    (aFlags & DISPLAY_CHILD_FORCE_PSEUDO_STACKING_CONTEXT) != 0;
  awayFromCommonPath |= pseudoStackingContext;
  if (!isSVG &&
      (aFlags & DISPLAY_CHILD_INLINE) &&
      !child->IsFrameOfType(eLineParticipant)) {
    // child is a non-inline frame in an inline context, i.e.,
    // it acts like inline-block or inline-table. Therefore it is a
    // pseudo-stacking-context.
    pseudoStackingContext = true;
    awayFromCommonPath = true;
  }

  // dirty rect in child-relative coordinates
  nsRect dirty = aDirtyRect - child->GetOffsetTo(this);

  nsDisplayListBuilder::OutOfFlowDisplayData* savedOutOfFlowData = nullptr;
  bool isPlaceholder = false;
  if (child->IsPlaceholderFrame()) {
    isPlaceholder = true;
    nsPlaceholderFrame* placeholder = static_cast<nsPlaceholderFrame*>(child);
    child = placeholder->GetOutOfFlowFrame();
    NS_ASSERTION(child, "No out of flow frame?");
    // If 'child' is a pushed float then it's owned by a block that's not an
    // ancestor of the placeholder, and it will be painted by that block and
    // should not be painted through the placeholder.
    if (!child || nsLayoutUtils::IsPopup(child) ||
        (child->GetStateBits() & NS_FRAME_IS_PUSHED_FLOAT))
      return;
    MOZ_ASSERT(child->GetStateBits() & NS_FRAME_OUT_OF_FLOW);
    // If the out-of-flow frame is in the top layer, the viewport frame
    // will paint it. Skip it here. Note that, only out-of-flow frames
    // with this property should be skipped, because non-HTML elements
    // may stop their children from being out-of-flow. Those frames
    // should still be handled in the normal in-flow path.
    if (placeholder->GetStateBits() & PLACEHOLDER_FOR_TOPLAYER) {
      return;
    }
    // Recheck NS_FRAME_TOO_DEEP_IN_FRAME_TREE
    if (child->GetStateBits() & NS_FRAME_TOO_DEEP_IN_FRAME_TREE)
      return;
    savedOutOfFlowData = nsDisplayListBuilder::GetOutOfFlowData(child);
    if (savedOutOfFlowData) {
      dirty = savedOutOfFlowData->mDirtyRect;
    } else {
      // The out-of-flow frame did not intersect the dirty area. We may still
      // need to traverse into it, since it may contain placeholders we need
      // to enter to reach other out-of-flow frames that are visible.
      dirty.SetEmpty();
    }
    pseudoStackingContext = true;
    awayFromCommonPath = true;
  }

  NS_ASSERTION(!child->IsPlaceholderFrame(),
               "Should have dealt with placeholders already");
  if (aBuilder->GetSelectedFramesOnly() &&
      child->IsLeaf() &&
      !aChild->IsSelected()) {
    return;
  }

  if (aBuilder->GetIncludeAllOutOfFlows() &&
      (child->GetStateBits() & NS_FRAME_OUT_OF_FLOW)) {
    dirty = child->GetVisualOverflowRect();
    awayFromCommonPath = true;
  } else if (!DescendIntoChild(aBuilder, child, dirty)) {
    return;
  }

  // XXX need to have inline-block and inline-table set pseudoStackingContext
  
  const nsStyleDisplay* ourDisp = StyleDisplay();
  // REVIEW: Taken from nsBoxFrame::Paint
  // Don't paint our children if the theme object is a leaf.
  if (IsThemed(ourDisp) &&
      !PresContext()->GetTheme()->WidgetIsContainer(ourDisp->mAppearance))
    return;

  // Since we're now sure that we're adding this frame to the display list
  // (which means we're painting it, modulo occlusion), mark it as visible
  // within the displayport.
  if (aBuilder->IsPaintingToWindow() && child->TrackingVisibility()) {
    child->PresContext()->PresShell()->EnsureFrameInApproximatelyVisibleList(child);
    awayFromCommonPath = true;
  }

  // Child is composited if it's transformed, partially transparent, or has
  // SVG effects or a blend mode..
  EffectSet* effectSet = EffectSet::GetEffectSet(this);
  const nsStyleDisplay* disp = child->StyleDisplay();
  const nsStyleEffects* effects = child->StyleEffects();
  const nsStylePosition* pos = child->StylePosition();
  bool isVisuallyAtomic = child->HasOpacity(effectSet)
    || child->IsTransformed(disp, effectSet)
    // strictly speaking, 'perspective' doesn't require visual atomicity,
    // but the spec says it acts like the rest of these
    || disp->mChildPerspective.GetUnit() == eStyleUnit_Coord
    || effects->mMixBlendMode != NS_STYLE_BLEND_NORMAL
    || nsSVGIntegrationUtils::UsingEffectsForFrame(child);

  bool isPositioned = disp->IsAbsPosContainingBlock(child);
  bool isStackingContext =
    (isPositioned && (disp->IsPositionForcingStackingContext() ||
                      pos->mZIndex.GetUnit() == eStyleUnit_Integer)) ||
     (disp->mWillChangeBitField & NS_STYLE_WILL_CHANGE_STACKING_CONTEXT) ||
     disp->mIsolation != NS_STYLE_ISOLATION_AUTO ||
     isVisuallyAtomic || (aFlags & DISPLAY_CHILD_FORCE_STACKING_CONTEXT);

  if (isVisuallyAtomic || isPositioned || (!isSVG && disp->IsFloating(child)) ||
      ((effects->mClipFlags & NS_STYLE_CLIP_RECT) &&
       IsSVGContentWithCSSClip(child)) ||
       disp->mIsolation != NS_STYLE_ISOLATION_AUTO ||
       (disp->mWillChangeBitField & NS_STYLE_WILL_CHANGE_STACKING_CONTEXT) ||
      (aFlags & DISPLAY_CHILD_FORCE_STACKING_CONTEXT)) {
    // If you change this, also change IsPseudoStackingContextFromStyle()
    pseudoStackingContext = true;
    awayFromCommonPath = true;
  }
  NS_ASSERTION(!isStackingContext || pseudoStackingContext,
               "Stacking contexts must also be pseudo-stacking-contexts");

  nsDisplayListBuilder::AutoBuildingDisplayList
    buildingForChild(aBuilder, child, dirty, pseudoStackingContext);
  DisplayListClipState::AutoClipMultiple clipState(aBuilder);
  nsDisplayListBuilder::AutoCurrentActiveScrolledRootSetter asrSetter(aBuilder);
  CheckForApzAwareEventHandlers(aBuilder, child);

  if (savedOutOfFlowData) {
    aBuilder->SetBuildingInvisibleItems(false);

    clipState.SetClipChainForContainingBlockDescendants(
      savedOutOfFlowData->mContainingBlockClipChain);
    asrSetter.SetCurrentActiveScrolledRoot(
      savedOutOfFlowData->mContainingBlockActiveScrolledRoot);
    MOZ_ASSERT(awayFromCommonPath, "It is impossible when savedOutOfFlowData is true");
  } else if (GetStateBits() & NS_FRAME_FORCE_DISPLAY_LIST_DESCEND_INTO &&
             isPlaceholder) {
    NS_ASSERTION(dirty.IsEmpty(), "should have empty dirty rect");
    // Every item we build from now until we descent into an out of flow that
    // does have saved out of flow data should be invisible. This state gets
    // restored when AutoBuildingDisplayList gets out of scope.
    aBuilder->SetBuildingInvisibleItems(true);

    // If we have nested out-of-flow frames and the outer one isn't visible
    // then we won't have stored clip data for it. We can just clear the clip
    // instead since we know we won't render anything, and the inner out-of-flow
    // frame will setup the correct clip for itself.
    clipState.SetClipChainForContainingBlockDescendants(nullptr);
    awayFromCommonPath = true;
  }

  // Setup clipping for the parent's overflow:-moz-hidden-unscrollable,
  // or overflow:hidden on elements that don't support scrolling (and therefore
  // don't create nsHTML/XULScrollFrame). This clipping needs to not clip
  // anything directly rendered by the parent, only the rendering of its
  // children.
  // Don't use overflowClip to restrict the dirty rect, since some of the
  // descendants may not be clipped by it. Even if we end up with unnecessary
  // display items, they'll be pruned during ComputeVisibility.
  nsIFrame* parent = child->GetParent();
  const nsStyleDisplay* parentDisp =
    parent == this ? ourDisp : parent->StyleDisplay();
  if (ApplyOverflowClipping(aBuilder, parent, parentDisp, clipState)) {
    awayFromCommonPath = true;
  }

  nsDisplayList list;
  nsDisplayList extraPositionedDescendants;
  const ActiveScrolledRoot* wrapListASR = aBuilder->CurrentActiveScrolledRoot();
  if (isStackingContext) {
    if (effects->mMixBlendMode != NS_STYLE_BLEND_NORMAL) {
      aBuilder->SetContainsBlendMode(true);
    }
    // True stacking context.
    // For stacking contexts, BuildDisplayListForStackingContext handles
    // clipping and MarkAbsoluteFramesForDisplayList.
    nsDisplayListBuilder::AutoContainerASRTracker contASRTracker(aBuilder);
    child->BuildDisplayListForStackingContext(aBuilder, dirty, &list);
    wrapListASR = contASRTracker.GetContainerASR();
    aBuilder->DisplayCaret(child, dirty, &list);
  } else {
    Maybe<nsRect> clipPropClip =
      child->GetClipPropClipRect(disp, effects, child->GetSize());
    if (clipPropClip) {
      dirty.IntersectRect(dirty, *clipPropClip);
      clipState.ClipContentDescendants(
        *clipPropClip + aBuilder->ToReferenceFrame(child));
      awayFromCommonPath = true;
    }

    child->MarkAbsoluteFramesForDisplayList(aBuilder, dirty);

    if (aBuilder->IsBuildingLayerEventRegions()) {
      // If this frame has a different animated geometry root than its parent,
      // make sure we accumulate event regions for its layer.
      if (buildingForChild.IsAnimatedGeometryRoot() || isPositioned) {
        nsDisplayLayerEventRegions* eventRegions =
          new (aBuilder) nsDisplayLayerEventRegions(aBuilder, child);
        eventRegions->AddFrame(aBuilder, child);
        aBuilder->SetLayerEventRegions(eventRegions);

        if (isPositioned) {
          // We need this nsDisplayLayerEventRegions to be sorted with the positioned
          // elements as positioned elements will be sorted on top of normal elements
          list.AppendNewToTop(eventRegions);
        } else {
          aLists.BorderBackground()->AppendNewToTop(eventRegions);
        }
      } else {
        nsDisplayLayerEventRegions* eventRegions = aBuilder->GetLayerEventRegions();
        if (eventRegions) {
          eventRegions->AddFrame(aBuilder, child);
        }
        if (!awayFromCommonPath &&
            aBuilder->IsPaintingToWindow() &&
            !buildingForChild.MaybeAnimatedGeometryRoot()) {
          // The shortcut is available for the child for next time.
          child->AddStateBits(NS_FRAME_SIMPLE_DISPLAYLIST);
        }
      }
    }

    if (!pseudoStackingContext) {
      // THIS IS THE COMMON CASE.
      // Not a pseudo or real stacking context. Do the simple thing and
      // return early.

      aBuilder->AdjustWindowDraggingRegion(child);
      child->BuildDisplayList(aBuilder, dirty, aLists);
      aBuilder->DisplayCaret(child, dirty, aLists.Content());
#ifdef DEBUG
      DisplayDebugBorders(aBuilder, child, aLists);
#endif
      return;
    }

    // A pseudo-stacking context (e.g., a positioned element with z-index auto).
    // We allow positioned descendants of the child to escape to our parent
    // stacking context's positioned descendant list, because they might be
    // z-index:non-auto
    nsDisplayListCollection pseudoStack;
    aBuilder->AdjustWindowDraggingRegion(child);
    nsDisplayListBuilder::AutoContainerASRTracker contASRTracker(aBuilder);
    child->BuildDisplayList(aBuilder, dirty, pseudoStack);
    aBuilder->DisplayCaret(child, dirty, pseudoStack.Content());
    wrapListASR = contASRTracker.GetContainerASR();

    list.AppendToTop(pseudoStack.BorderBackground());
    list.AppendToTop(pseudoStack.BlockBorderBackgrounds());
    list.AppendToTop(pseudoStack.Floats());
    list.AppendToTop(pseudoStack.Content());
    list.AppendToTop(pseudoStack.Outlines());
    extraPositionedDescendants.AppendToTop(pseudoStack.PositionedDescendants());
#ifdef DEBUG
    DisplayDebugBorders(aBuilder, child, aLists);
#endif
  }

  buildingForChild.RestoreBuildingInvisibleItemsValue();
 
  // Clear clip rect for the construction of the items below. Since we're
  // clipping all their contents, they themselves don't need to be clipped.
  clipState.ClearUpToASR(wrapListASR);

  if (isPositioned || isVisuallyAtomic ||
      (aFlags & DISPLAY_CHILD_FORCE_STACKING_CONTEXT)) {
    // Genuine stacking contexts, and positioned pseudo-stacking-contexts,
    // go in this level.
    if (!list.IsEmpty()) {
      nsDisplayItem* item = WrapInWrapList(aBuilder, child, &list, wrapListASR);
      if (isSVG) {
        aLists.Content()->AppendNewToTop(item);
      } else {
        aLists.PositionedDescendants()->AppendNewToTop(item);
      }
    }
  } else if (!isSVG && disp->IsFloating(child)) {
    if (!list.IsEmpty()) {
      aLists.Floats()->AppendNewToTop(WrapInWrapList(aBuilder, child, &list, wrapListASR));
    }
  } else {
    aLists.Content()->AppendToTop(&list);
  }
  // We delay placing the positioned descendants of positioned frames to here,
  // because in the absence of z-index this is the correct order for them.
  // This doesn't affect correctness because the positioned descendants list
  // is sorted by z-order and content in BuildDisplayListForStackingContext,
  // but it means that sort routine needs to do less work.
  aLists.PositionedDescendants()->AppendToTop(&extraPositionedDescendants);
}

void
nsIFrame::MarkAbsoluteFramesForDisplayList(nsDisplayListBuilder* aBuilder,
                                           const nsRect& aDirtyRect)
{
  if (IsAbsoluteContainer()) {
    aBuilder->MarkFramesForDisplayList(this, GetAbsoluteContainingBlock()->GetChildList(), aDirtyRect);
  }
}

nsresult  
nsFrame::GetContentForEvent(WidgetEvent* aEvent,
                            nsIContent** aContent)
{
  nsIFrame* f = nsLayoutUtils::GetNonGeneratedAncestor(this);
  *aContent = f->GetContent();
  NS_IF_ADDREF(*aContent);
  return NS_OK;
}

void
nsFrame::FireDOMEvent(const nsAString& aDOMEventName, nsIContent *aContent)
{
  nsIContent* target = aContent ? aContent : mContent;

  if (target) {
    RefPtr<AsyncEventDispatcher> asyncDispatcher =
      new AsyncEventDispatcher(target, aDOMEventName, true, false);
    DebugOnly<nsresult> rv = asyncDispatcher->PostDOMEvent();
    NS_ASSERTION(NS_SUCCEEDED(rv), "AsyncEventDispatcher failed to dispatch");
  }
}

nsresult
nsFrame::HandleEvent(nsPresContext* aPresContext, 
                     WidgetGUIEvent* aEvent,
                     nsEventStatus* aEventStatus)
{

  if (aEvent->mMessage == eMouseMove) {
    // XXX If the second argument of HandleDrag() is WidgetMouseEvent,
    //     the implementation becomes simpler.
    return HandleDrag(aPresContext, aEvent, aEventStatus);
  }

  if ((aEvent->mClass == eMouseEventClass &&
       aEvent->AsMouseEvent()->button == WidgetMouseEvent::eLeftButton) ||
      aEvent->mClass == eTouchEventClass) {
    if (aEvent->mMessage == eMouseDown || aEvent->mMessage == eTouchStart) {
      HandlePress(aPresContext, aEvent, aEventStatus);
    } else if (aEvent->mMessage == eMouseUp || aEvent->mMessage == eTouchEnd) {
      HandleRelease(aPresContext, aEvent, aEventStatus);
    }
  }
  return NS_OK;
}

NS_IMETHODIMP
nsFrame::GetDataForTableSelection(const nsFrameSelection* aFrameSelection,
                                  nsIPresShell* aPresShell,
                                  WidgetMouseEvent* aMouseEvent, 
                                  nsIContent** aParentContent,
                                  int32_t* aContentOffset,
                                  int32_t* aTarget)
{
  if (!aFrameSelection || !aPresShell || !aMouseEvent || !aParentContent || !aContentOffset || !aTarget)
    return NS_ERROR_NULL_POINTER;

  *aParentContent = nullptr;
  *aContentOffset = 0;
  *aTarget = 0;

  int16_t displaySelection = aPresShell->GetSelectionFlags();

  bool selectingTableCells = aFrameSelection->GetTableCellSelection();

  // DISPLAY_ALL means we're in an editor.
  // If already in cell selection mode, 
  //  continue selecting with mouse drag or end on mouse up,
  //  or when using shift key to extend block of cells
  //  (Mouse down does normal selection unless Ctrl/Cmd is pressed)
  bool doTableSelection =
     displaySelection == nsISelectionDisplay::DISPLAY_ALL && selectingTableCells &&
     (aMouseEvent->mMessage == eMouseMove ||
      (aMouseEvent->mMessage == eMouseUp &&
       aMouseEvent->button == WidgetMouseEvent::eLeftButton) ||
      aMouseEvent->IsShift());

  if (!doTableSelection)
  {  
    // In Browser, special 'table selection' key must be pressed for table selection
    // or when just Shift is pressed and we're already in table/cell selection mode
#ifdef XP_MACOSX
    doTableSelection = aMouseEvent->IsMeta() || (aMouseEvent->IsShift() && selectingTableCells);
#else
    doTableSelection = aMouseEvent->IsControl() || (aMouseEvent->IsShift() && selectingTableCells);
#endif
  }
  if (!doTableSelection) 
    return NS_OK;

  // Get the cell frame or table frame (or parent) of the current content node
  nsIFrame *frame = this;
  bool foundCell = false;
  bool foundTable = false;

  // Get the limiting node to stop parent frame search
  nsIContent* limiter = aFrameSelection->GetLimiter();

  // If our content node is an ancestor of the limiting node,
  // we should stop the search right now.
  if (limiter && nsContentUtils::ContentIsDescendantOf(limiter, GetContent()))
    return NS_OK;

  //We don't initiate row/col selection from here now,
  //  but we may in future
  //bool selectColumn = false;
  //bool selectRow = false;
  
  while (frame)
  {
    // Check for a table cell by querying to a known CellFrame interface
    nsITableCellLayout *cellElement = do_QueryFrame(frame);
    if (cellElement)
    {
      foundCell = true;
      //TODO: If we want to use proximity to top or left border
      //      for row and column selection, this is the place to do it
      break;
    }
    else
    {
      // If not a cell, check for table
      // This will happen when starting frame is the table or child of a table,
      //  such as a row (we were inbetween cells or in table border)
      nsTableWrapperFrame *tableFrame = do_QueryFrame(frame);
      if (tableFrame)
      {
        foundTable = true;
        //TODO: How can we select row when along left table edge
        //  or select column when along top edge?
        break;
      } else {
        frame = frame->GetParent();
        // Stop if we have hit the selection's limiting content node
        if (frame && frame->GetContent() == limiter)
          break;
      }
    }
  }
  // We aren't in a cell or table
  if (!foundCell && !foundTable) return NS_OK;

  nsIContent* tableOrCellContent = frame->GetContent();
  if (!tableOrCellContent) return NS_ERROR_FAILURE;

  nsCOMPtr<nsIContent> parentContent = tableOrCellContent->GetParent();
  if (!parentContent) return NS_ERROR_FAILURE;

  int32_t offset = parentContent->IndexOf(tableOrCellContent);
  // Not likely?
  if (offset < 0) return NS_ERROR_FAILURE;

  // Everything is OK -- set the return values
  parentContent.forget(aParentContent);

  *aContentOffset = offset;

#if 0
  if (selectRow)
    *aTarget = nsISelectionPrivate::TABLESELECTION_ROW;
  else if (selectColumn)
    *aTarget = nsISelectionPrivate::TABLESELECTION_COLUMN;
  else 
#endif
  if (foundCell)
    *aTarget = nsISelectionPrivate::TABLESELECTION_CELL;
  else if (foundTable)
    *aTarget = nsISelectionPrivate::TABLESELECTION_TABLE;

  return NS_OK;
}

bool
nsIFrame::IsSelectable(StyleUserSelect* aSelectStyle) const
{
  // it's ok if aSelectStyle is null

  // Like 'visibility', we must check all the parents: if a parent
  // is not selectable, none of its children is selectable.
  //
  // The -moz-all value acts similarly: if a frame has 'user-select:-moz-all',
  // all its children are selectable, even those with 'user-select:none'.
  //
  // As a result, if 'none' and '-moz-all' are not present in the frame hierarchy,
  // aSelectStyle returns the first style that is not AUTO. If these values
  // are present in the frame hierarchy, aSelectStyle returns the style of the
  // topmost parent that has either 'none' or '-moz-all'.
  //
  // The -moz-text value acts as a way to override an ancestor's all/-moz-all value.
  //
  // For instance, if the frame hierarchy is:
  //    AUTO     -> _MOZ_ALL  -> NONE -> TEXT,      the returned value is ALL
  //    AUTO     -> _MOZ_ALL  -> NONE -> _MOZ_TEXT, the returned value is TEXT.
  //    TEXT     -> NONE      -> AUTO -> _MOZ_ALL,  the returned value is TEXT
  //    _MOZ_ALL -> TEXT      -> AUTO -> AUTO,      the returned value is ALL
  //    _MOZ_ALL -> _MOZ_TEXT -> AUTO -> AUTO,      the returned value is TEXT.
  //    AUTO     -> CELL      -> TEXT -> AUTO,      the returned value is TEXT
  //
  StyleUserSelect selectStyle  = StyleUserSelect::Auto;
  nsIFrame* frame              = const_cast<nsIFrame*>(this);
  bool containsEditable        = false;

  while (frame) {
    const nsStyleUIReset* userinterface = frame->StyleUIReset();
    switch (userinterface->mUserSelect) {
      case StyleUserSelect::All:
      case StyleUserSelect::MozAll:
      {
        // override the previous values
        if (selectStyle != StyleUserSelect::MozText) {
          selectStyle = userinterface->mUserSelect;
        }
        nsIContent* frameContent = frame->GetContent();
        containsEditable = frameContent &&
          frameContent->EditableDescendantCount() > 0;
        break;
      }
      default:
        // otherwise return the first value which is not 'auto'
        if (selectStyle == StyleUserSelect::Auto) {
          selectStyle = userinterface->mUserSelect;
        }
        break;
    }
    frame = nsLayoutUtils::GetParentOrPlaceholderFor(frame);
  }

  // convert internal values to standard values
  if (selectStyle == StyleUserSelect::Auto ||
      selectStyle == StyleUserSelect::MozText) {
    selectStyle = StyleUserSelect::Text;
  } else if (selectStyle == StyleUserSelect::MozAll) {
    selectStyle = StyleUserSelect::All;
  }

  // If user tries to select all of a non-editable content,
  // prevent selection if it contains editable content.
  bool allowSelection = true;
  if (selectStyle == StyleUserSelect::All) {
    allowSelection = !containsEditable;
  }

  // return stuff
  if (aSelectStyle) {
    *aSelectStyle = selectStyle;
  }

  return !(mState & NS_FRAME_GENERATED_CONTENT) &&
         allowSelection &&
         selectStyle != StyleUserSelect::None;
}

/**
  * Handles the Mouse Press Event for the frame
 */
NS_IMETHODIMP
nsFrame::HandlePress(nsPresContext* aPresContext, 
                     WidgetGUIEvent* aEvent,
                     nsEventStatus* aEventStatus)
{
  NS_ENSURE_ARG_POINTER(aEventStatus);
  if (nsEventStatus_eConsumeNoDefault == *aEventStatus) {
    return NS_OK;
  }

  NS_ENSURE_ARG_POINTER(aEvent);
  if (aEvent->mClass == eTouchEventClass) {
    return NS_OK;
  }

  //We often get out of sync state issues with mousedown events that
  //get interrupted by alerts/dialogs.
  //Check with the ESM to see if we should process this one
  if (!aPresContext->EventStateManager()->EventStatusOK(aEvent)) 
    return NS_OK;

  nsIPresShell *shell = aPresContext->GetPresShell();
  if (!shell)
    return NS_ERROR_FAILURE;

  // if we are in Navigator and the click is in a draggable node, we don't want
  // to start selection because we don't want to interfere with a potential
  // drag of said node and steal all its glory.
  int16_t isEditor = shell->GetSelectionFlags();
  //weaaak. only the editor can display frame selection not just text and images
  isEditor = isEditor == nsISelectionDisplay::DISPLAY_ALL;

  WidgetMouseEvent* mouseEvent = aEvent->AsMouseEvent();

  if (!mouseEvent->IsAlt()) {
    for (nsIContent* content = mContent; content;
         content = content->GetParent()) {
      if (nsContentUtils::ContentIsDraggable(content) &&
          !content->IsEditable()) {
        // coordinate stuff is the fix for bug #55921
        if ((mRect - GetPosition()).Contains(
              nsLayoutUtils::GetEventCoordinatesRelativeTo(mouseEvent, this))) {
          return NS_OK;
        }
      }
    }
  }

  // check whether style allows selection
  // if not, don't tell selection the mouse event even occurred.  
  StyleUserSelect selectStyle;
  // check for select: none
  if (!IsSelectable(&selectStyle)) {
    return NS_OK;
  }

  // When implementing StyleUserSelect::Element, StyleUserSelect::Elements and
  // StyleUserSelect::Toggle, need to change this logic
  bool useFrameSelection = (selectStyle == StyleUserSelect::Text);

  // If the mouse is dragged outside the nearest enclosing scrollable area
  // while making a selection, the area will be scrolled. To do this, capture
  // the mouse on the nearest scrollable frame. If there isn't a scrollable
  // frame, or something else is already capturing the mouse, there's no
  // reason to capture.
  bool hasCapturedContent = false;
  if (!nsIPresShell::GetCapturingContent()) {
    nsIScrollableFrame* scrollFrame =
      nsLayoutUtils::GetNearestScrollableFrame(this,
        nsLayoutUtils::SCROLLABLE_SAME_DOC |
        nsLayoutUtils::SCROLLABLE_INCLUDE_HIDDEN);
    if (scrollFrame) {
      nsIFrame* capturingFrame = do_QueryFrame(scrollFrame);
      nsIPresShell::SetCapturingContent(capturingFrame->GetContent(),
                                        CAPTURE_IGNOREALLOWED);
      hasCapturedContent = true;
    }
  }

  // XXX This is screwy; it really should use the selection frame, not the
  // event frame
  const nsFrameSelection* frameselection = nullptr;
  if (useFrameSelection)
    frameselection = GetConstFrameSelection();
  else
    frameselection = shell->ConstFrameSelection();

  if (!frameselection || frameselection->GetDisplaySelection() == nsISelectionController::SELECTION_OFF)
    return NS_OK;//nothing to do we cannot affect selection from here

#ifdef XP_MACOSX
  if (mouseEvent->IsControl())
    return NS_OK;//short circuit. hard coded for mac due to time restraints.
  bool control = mouseEvent->IsMeta();
#else
  bool control = mouseEvent->IsControl();
#endif

  RefPtr<nsFrameSelection> fc = const_cast<nsFrameSelection*>(frameselection);
  if (mouseEvent->mClickCount > 1) {
    // These methods aren't const but can't actually delete anything,
    // so no need for AutoWeakFrame.
    fc->SetDragState(true);
    fc->SetMouseDoubleDown(true);
    return HandleMultiplePress(aPresContext, mouseEvent, aEventStatus, control);
  }

  nsPoint pt = nsLayoutUtils::GetEventCoordinatesRelativeTo(mouseEvent, this);
  ContentOffsets offsets = GetContentOffsetsFromPoint(pt, SKIP_HIDDEN);

  if (!offsets.content)
    return NS_ERROR_FAILURE;

  // On touchables devices, touch the screen is usually a pan action,
  // so let's reposition the caret if needed but do not select text
  // if the touch did not happen over an editable element.  Otherwise,
  // let the user move the caret by tapping and dragging.
  if (!offsets.content->IsEditable() &&
      Preferences::GetBool("browser.ignoreNativeFrameTextSelection", false)) {
    // On touchables devices, mouse events are generated if the gesture is a tap.
    // Such events are never going to generate a drag action, so let's release
    // captured content if any.
    if (hasCapturedContent) {
      nsIPresShell::SetCapturingContent(nullptr, 0);
    }

    return fc->HandleClick(offsets.content, offsets.StartOffset(),
                           offsets.EndOffset(), false, false,
                           offsets.associate);
  }

  // Let Ctrl/Cmd+mouse down do table selection instead of drag initiation
  nsCOMPtr<nsIContent>parentContent;
  int32_t  contentOffset;
  int32_t target;
  nsresult rv;
  rv = GetDataForTableSelection(frameselection, shell, mouseEvent,
                                getter_AddRefs(parentContent), &contentOffset,
                                &target);
  if (NS_SUCCEEDED(rv) && parentContent)
  {
    fc->SetDragState(true);
    return fc->HandleTableSelection(parentContent, contentOffset, target,
                                    mouseEvent);
  }

  fc->SetDelayedCaretData(0);

  // Check if any part of this frame is selected, and if the
  // user clicked inside the selected region. If so, we delay
  // starting a new selection since the user may be trying to
  // drag the selected region to some other app.

  if (GetContent()->IsSelectionDescendant())
  {
    bool inSelection = false;
    UniquePtr<SelectionDetails> details
      = frameselection->LookUpSelection(offsets.content, 0,
                                        offsets.EndOffset(), false);

    //
    // If there are any details, check to see if the user clicked
    // within any selected region of the frame.
    //

    for (SelectionDetails* curDetail = details.get();
         curDetail;
         curDetail = curDetail->mNext.get()) {
      //
      // If the user clicked inside a selection, then just
      // return without doing anything. We will handle placing
      // the caret later on when the mouse is released. We ignore
      // the spellcheck, find and url formatting selections.
      //
      if (curDetail->mSelectionType != SelectionType::eSpellCheck &&
          curDetail->mSelectionType != SelectionType::eFind &&
          curDetail->mSelectionType != SelectionType::eURLSecondary &&
          curDetail->mSelectionType != SelectionType::eURLStrikeout &&
          curDetail->mStart <= offsets.StartOffset() &&
          offsets.EndOffset() <= curDetail->mEnd)
      {
        inSelection = true;
      }
    }

    if (inSelection) {
      fc->SetDragState(false);
      fc->SetDelayedCaretData(mouseEvent);
      return NS_OK;
    }
  }

  fc->SetDragState(true);

  // Do not touch any nsFrame members after this point without adding
  // weakFrame checks.
  rv = fc->HandleClick(offsets.content, offsets.StartOffset(),
                       offsets.EndOffset(), mouseEvent->IsShift(), control,
                       offsets.associate);

  if (NS_FAILED(rv))
    return rv;

  if (offsets.offset != offsets.secondaryOffset)
    fc->MaintainSelection();

  if (isEditor && !mouseEvent->IsShift() &&
      (offsets.EndOffset() - offsets.StartOffset()) == 1)
  {
    // A single node is selected and we aren't extending an existing
    // selection, which means the user clicked directly on an object (either
    // -moz-user-select: all or a non-text node without children).
    // Therefore, disable selection extension during mouse moves.
    // XXX This is a bit hacky; shouldn't editor be able to deal with this?
    fc->SetDragState(false);
  }

  return rv;
}

/*
 * SelectByTypeAtPoint
 *
 * Search for selectable content at point and attempt to select
 * based on the start and end selection behaviours.
 *
 * @param aPresContext Presentation context
 * @param aPoint Point at which selection will occur. Coordinates
 * should be relaitve to this frame.
 * @param aBeginAmountType, aEndAmountType Selection behavior, see
 * nsIFrame for definitions.
 * @param aSelectFlags Selection flags defined in nsFame.h.
 * @return success or failure at finding suitable content to select.
 */
nsresult
nsFrame::SelectByTypeAtPoint(nsPresContext* aPresContext,
                             const nsPoint& aPoint,
                             nsSelectionAmount aBeginAmountType,
                             nsSelectionAmount aEndAmountType,
                             uint32_t aSelectFlags)
{
  NS_ENSURE_ARG_POINTER(aPresContext);

  // No point in selecting if selection is turned off
  if (DisplaySelection(aPresContext) == nsISelectionController::SELECTION_OFF)
    return NS_OK;

  ContentOffsets offsets = GetContentOffsetsFromPoint(aPoint, SKIP_HIDDEN);
  if (!offsets.content)
    return NS_ERROR_FAILURE;

  int32_t offset;
  const nsFrameSelection* frameSelection =
    PresContext()->GetPresShell()->ConstFrameSelection();
  nsIFrame* theFrame = frameSelection->
    GetFrameForNodeOffset(offsets.content, offsets.offset,
                          offsets.associate, &offset);
  if (!theFrame)
    return NS_ERROR_FAILURE;

  nsFrame* frame = static_cast<nsFrame*>(theFrame);
  return frame->PeekBackwardAndForward(aBeginAmountType, aEndAmountType, offset,
                                       aBeginAmountType != eSelectWord,
                                       aSelectFlags);
}

/**
  * Multiple Mouse Press -- line or paragraph selection -- for the frame.
  * Wouldn't it be nice if this didn't have to be hardwired into Frame code?
 */
NS_IMETHODIMP
nsFrame::HandleMultiplePress(nsPresContext* aPresContext,
                             WidgetGUIEvent* aEvent,
                             nsEventStatus* aEventStatus,
                             bool aControlHeld)
{
  NS_ENSURE_ARG_POINTER(aEvent);
  NS_ENSURE_ARG_POINTER(aEventStatus);

  if (nsEventStatus_eConsumeNoDefault == *aEventStatus ||
      DisplaySelection(aPresContext) == nsISelectionController::SELECTION_OFF) {
    return NS_OK;
  }

  // Find out whether we're doing line or paragraph selection.
  // If browser.triple_click_selects_paragraph is true, triple-click selects paragraph.
  // Otherwise, triple-click selects line, and quadruple-click selects paragraph
  // (on platforms that support quadruple-click).
  nsSelectionAmount beginAmount, endAmount;
  WidgetMouseEvent* mouseEvent = aEvent->AsMouseEvent();
  if (!mouseEvent) {
    return NS_OK;
  }

  if (mouseEvent->mClickCount == 4) {
    beginAmount = endAmount = eSelectParagraph;
  } else if (mouseEvent->mClickCount == 3) {
    if (Preferences::GetBool("browser.triple_click_selects_paragraph")) {
      beginAmount = endAmount = eSelectParagraph;
    } else {
      beginAmount = eSelectBeginLine;
      endAmount = eSelectEndLine;
    }
  } else if (mouseEvent->mClickCount == 2) {
    // We only want inline frames; PeekBackwardAndForward dislikes blocks
    beginAmount = endAmount = eSelectWord;
  } else {
    return NS_OK;
  }

  nsPoint relPoint =
    nsLayoutUtils::GetEventCoordinatesRelativeTo(mouseEvent, this);
  return SelectByTypeAtPoint(aPresContext, relPoint, beginAmount, endAmount,
                             (aControlHeld ? SELECT_ACCUMULATE : 0));
}

nsresult
nsFrame::PeekBackwardAndForward(nsSelectionAmount aAmountBack,
                                nsSelectionAmount aAmountForward,
                                int32_t aStartPos,
                                bool aJumpLines,
                                uint32_t aSelectFlags)
{
  nsIFrame* baseFrame = this;
  int32_t baseOffset = aStartPos;
  nsresult rv;

  if (aAmountBack == eSelectWord) {
    // To avoid selecting the previous word when at start of word,
    // first move one character forward.
    nsPeekOffsetStruct pos(eSelectCharacter,
                           eDirNext,
                           aStartPos,
                           nsPoint(0, 0),
                           aJumpLines,
                           true,  //limit on scrolled views
                           false,
                           false,
                           false);
    rv = PeekOffset(&pos);
    if (NS_SUCCEEDED(rv)) {
      baseFrame = pos.mResultFrame;
      baseOffset = pos.mContentOffset;
    }
  }

  // Use peek offset one way then the other:
  nsPeekOffsetStruct startpos(aAmountBack,
                              eDirPrevious,
                              baseOffset,
                              nsPoint(0, 0),
                              aJumpLines,
                              true,  //limit on scrolled views
                              false,
                              false,
                              false);
  rv = baseFrame->PeekOffset(&startpos);
  if (NS_FAILED(rv))
    return rv;

  nsPeekOffsetStruct endpos(aAmountForward,
                            eDirNext,
                            aStartPos,
                            nsPoint(0, 0),
                            aJumpLines,
                            true,  //limit on scrolled views
                            false,
                            false,
                            false);
  rv = PeekOffset(&endpos);
  if (NS_FAILED(rv))
    return rv;

  // Keep frameSelection alive.
  RefPtr<nsFrameSelection> frameSelection = GetFrameSelection();

  rv = frameSelection->HandleClick(startpos.mResultContent,
                                   startpos.mContentOffset, startpos.mContentOffset,
                                   false, (aSelectFlags & SELECT_ACCUMULATE),
                                   CARET_ASSOCIATE_AFTER);
  if (NS_FAILED(rv))
    return rv;

  rv = frameSelection->HandleClick(endpos.mResultContent,
                                   endpos.mContentOffset, endpos.mContentOffset,
                                   true, false,
                                   CARET_ASSOCIATE_BEFORE);
  if (NS_FAILED(rv))
    return rv;

  // maintain selection
  return frameSelection->MaintainSelection(aAmountBack);
}

NS_IMETHODIMP nsFrame::HandleDrag(nsPresContext* aPresContext, 
                                  WidgetGUIEvent* aEvent,
                                  nsEventStatus* aEventStatus)
{
  MOZ_ASSERT(aEvent->mClass == eMouseEventClass,
             "HandleDrag can only handle mouse event");

  RefPtr<nsFrameSelection> frameselection = GetFrameSelection();
  bool mouseDown = frameselection->GetDragState();
  if (!mouseDown) {
    return NS_OK;
  }

  nsIFrame* scrollbar =
    nsLayoutUtils::GetClosestFrameOfType(this, LayoutFrameType::Scrollbar);
  if (!scrollbar) {
    // XXX Do we really need to exclude non-selectable content here?
    // GetContentOffsetsFromPoint can handle it just fine, although some
    // other stuff might not like it.
    // NOTE: DisplaySelection() returns SELECTION_OFF for non-selectable frames.
    if (DisplaySelection(aPresContext) == nsISelectionController::SELECTION_OFF) {
      return NS_OK;
    }
  }

  frameselection->StopAutoScrollTimer();

  // Check if we are dragging in a table cell
  nsCOMPtr<nsIContent> parentContent;
  int32_t contentOffset;
  int32_t target;
  WidgetMouseEvent* mouseEvent = aEvent->AsMouseEvent();
  nsCOMPtr<nsIPresShell> presShell = aPresContext->PresShell();
  nsresult result;
  result = GetDataForTableSelection(frameselection, presShell, mouseEvent,
                                    getter_AddRefs(parentContent),
                                    &contentOffset, &target);      

  AutoWeakFrame weakThis = this;
  if (NS_SUCCEEDED(result) && parentContent) {
    frameselection->HandleTableSelection(parentContent, contentOffset, target,
                                         mouseEvent);
  } else {
    nsPoint pt = nsLayoutUtils::GetEventCoordinatesRelativeTo(mouseEvent, this);
    frameselection->HandleDrag(this, pt);
  }

  // The frameselection object notifies selection listeners synchronously above
  // which might have killed us.
  if (!weakThis.IsAlive()) {
    return NS_OK;
  }

  // get the nearest scrollframe
  nsIScrollableFrame* scrollFrame =
    nsLayoutUtils::GetNearestScrollableFrame(this,
        nsLayoutUtils::SCROLLABLE_SAME_DOC |
        nsLayoutUtils::SCROLLABLE_INCLUDE_HIDDEN);

  if (scrollFrame) {
    nsIFrame* capturingFrame = scrollFrame->GetScrolledFrame();
    if (capturingFrame) {
      nsPoint pt = nsLayoutUtils::GetEventCoordinatesRelativeTo(mouseEvent,
                                                                capturingFrame);
      frameselection->StartAutoScrollTimer(capturingFrame, pt, 30);
    }
  }

  return NS_OK;
}

/**
 * This static method handles part of the nsFrame::HandleRelease in a way
 * which doesn't rely on the nsFrame object to stay alive.
 */
static nsresult
HandleFrameSelection(nsFrameSelection*         aFrameSelection,
                     nsIFrame::ContentOffsets& aOffsets,
                     bool                      aHandleTableSel,
                     int32_t                   aContentOffsetForTableSel,
                     int32_t                   aTargetForTableSel,
                     nsIContent*               aParentContentForTableSel,
                     WidgetGUIEvent*           aEvent,
                     nsEventStatus*            aEventStatus)
{
  if (!aFrameSelection) {
    return NS_OK;
  }

  nsresult rv = NS_OK;

  if (nsEventStatus_eConsumeNoDefault != *aEventStatus) {
    if (!aHandleTableSel) {
      if (!aOffsets.content || !aFrameSelection->HasDelayedCaretData()) {
        return NS_ERROR_FAILURE;
      }

      // We are doing this to simulate what we would have done on HandlePress.
      // We didn't do it there to give the user an opportunity to drag
      // the text, but since they didn't drag, we want to place the
      // caret.
      // However, we'll use the mouse position from the release, since:
      //  * it's easier
      //  * that's the normal click position to use (although really, in
      //    the normal case, small movements that don't count as a drag
      //    can do selection)
      aFrameSelection->SetDragState(true);

      rv = aFrameSelection->HandleClick(aOffsets.content,
                                        aOffsets.StartOffset(),
                                        aOffsets.EndOffset(),
                                        aFrameSelection->IsShiftDownInDelayedCaretData(),
                                        false,
                                        aOffsets.associate);
      if (NS_FAILED(rv)) {
        return rv;
      }
    } else if (aParentContentForTableSel) {
      aFrameSelection->SetDragState(false);
      rv = aFrameSelection->HandleTableSelection(
                              aParentContentForTableSel,
                              aContentOffsetForTableSel,
                              aTargetForTableSel,
                              aEvent->AsMouseEvent());
      if (NS_FAILED(rv)) {
        return rv;
      }
    }
    aFrameSelection->SetDelayedCaretData(0);
  }

  aFrameSelection->SetDragState(false);
  aFrameSelection->StopAutoScrollTimer();

  return NS_OK;
}

NS_IMETHODIMP nsFrame::HandleRelease(nsPresContext* aPresContext,
                                     WidgetGUIEvent* aEvent,
                                     nsEventStatus* aEventStatus)
{
  if (aEvent->mClass != eMouseEventClass) {
    return NS_OK;
  }

  nsIFrame* activeFrame = GetActiveSelectionFrame(aPresContext, this);

  nsCOMPtr<nsIContent> captureContent = nsIPresShell::GetCapturingContent();

  // We can unconditionally stop capturing because
  // we should never be capturing when the mouse button is up
  nsIPresShell::SetCapturingContent(nullptr, 0);

  bool selectionOff =
    (DisplaySelection(aPresContext) == nsISelectionController::SELECTION_OFF);

  RefPtr<nsFrameSelection> frameselection;
  ContentOffsets offsets;
  nsCOMPtr<nsIContent> parentContent;
  int32_t contentOffsetForTableSel = 0;
  int32_t targetForTableSel = 0;
  bool handleTableSelection = true;

  if (!selectionOff) {
    frameselection = GetFrameSelection();
    if (nsEventStatus_eConsumeNoDefault != *aEventStatus && frameselection) {
      // Check if the frameselection recorded the mouse going down.
      // If not, the user must have clicked in a part of the selection.
      // Place the caret before continuing!

      if (frameselection->MouseDownRecorded()) {
        nsPoint pt = nsLayoutUtils::GetEventCoordinatesRelativeTo(aEvent, this);
        offsets = GetContentOffsetsFromPoint(pt, SKIP_HIDDEN);
        handleTableSelection = false;
      } else {
        GetDataForTableSelection(frameselection, PresContext()->PresShell(),
                                 aEvent->AsMouseEvent(),
                                 getter_AddRefs(parentContent),
                                 &contentOffsetForTableSel,
                                 &targetForTableSel);
      }
    }
  }

  // We might be capturing in some other document and the event just happened to
  // trickle down here. Make sure that document's frame selection is notified.
  // Note, this may cause the current nsFrame object to be deleted, bug 336592.
  RefPtr<nsFrameSelection> frameSelection;
  if (activeFrame != this &&
      static_cast<nsFrame*>(activeFrame)->DisplaySelection(activeFrame->PresContext())
        != nsISelectionController::SELECTION_OFF) {
      frameSelection = activeFrame->GetFrameSelection();
  }

  // Also check the selection of the capturing content which might be in a
  // different document.
  if (!frameSelection && captureContent) {
    nsIDocument* doc = captureContent->GetUncomposedDoc();
    if (doc) {
      nsIPresShell* capturingShell = doc->GetShell();
      if (capturingShell && capturingShell != PresContext()->GetPresShell()) {
        frameSelection = capturingShell->FrameSelection();
      }
    }
  }

  if (frameSelection) {
    frameSelection->SetDragState(false);
    frameSelection->StopAutoScrollTimer();
    nsIScrollableFrame* scrollFrame =
      nsLayoutUtils::GetNearestScrollableFrame(this,
        nsLayoutUtils::SCROLLABLE_SAME_DOC |
        nsLayoutUtils::SCROLLABLE_INCLUDE_HIDDEN);
    if (scrollFrame) {
      // Perform any additional scrolling needed to maintain CSS snap point
      // requirements when autoscrolling is over.
      scrollFrame->ScrollSnap();
    }
  }

  // Do not call any methods of the current object after this point!!!
  // The object is perhaps dead!

  return selectionOff
    ? NS_OK
    : HandleFrameSelection(frameselection, offsets, handleTableSelection,
                           contentOffsetForTableSel, targetForTableSel,
                           parentContent, aEvent, aEventStatus);
}

struct MOZ_STACK_CLASS FrameContentRange {
  FrameContentRange(nsIContent* aContent, int32_t aStart, int32_t aEnd) :
    content(aContent), start(aStart), end(aEnd) { }
  nsCOMPtr<nsIContent> content;
  int32_t start;
  int32_t end;
};

// Retrieve the content offsets of a frame
static FrameContentRange GetRangeForFrame(nsIFrame* aFrame) {
  nsCOMPtr<nsIContent> content, parent;
  content = aFrame->GetContent();
  if (!content) {
    NS_WARNING("Frame has no content");
    return FrameContentRange(nullptr, -1, -1);
  }
  LayoutFrameType type = aFrame->Type();
  if (type == LayoutFrameType::Text) {
    int32_t offset, offsetEnd;
    aFrame->GetOffsets(offset, offsetEnd);
    return FrameContentRange(content, offset, offsetEnd);
  }
  if (type == LayoutFrameType::Br) {
    parent = content->GetParent();
    int32_t beginOffset = parent->IndexOf(content);
    return FrameContentRange(parent, beginOffset, beginOffset);
  }
  // Loop to deal with anonymous content, which has no index; this loop
  // probably won't run more than twice under normal conditions
  do {
    parent  = content->GetParent();
    if (parent) {
      int32_t beginOffset = parent->IndexOf(content);
      if (beginOffset >= 0)
        return FrameContentRange(parent, beginOffset, beginOffset + 1);
      content = parent;
    }
  } while (parent);

  // The root content node must act differently
  return FrameContentRange(content, 0, content->GetChildCount());
}

// The FrameTarget represents the closest frame to a point that can be selected
// The frame is the frame represented, frameEdge says whether one end of the
// frame is the result (in which case different handling is needed), and
// afterFrame says which end is repersented if frameEdge is true
struct FrameTarget {
  FrameTarget(nsIFrame* aFrame, bool aFrameEdge, bool aAfterFrame,
              bool aEmptyBlock = false) :
    frame(aFrame), frameEdge(aFrameEdge), afterFrame(aAfterFrame),
    emptyBlock(aEmptyBlock) { }
  static FrameTarget Null() {
    return FrameTarget(nullptr, false, false);
  }
  bool IsNull() {
    return !frame;
  }
  nsIFrame* frame;
  bool frameEdge;
  bool afterFrame;
  bool emptyBlock;
};

// See function implementation for information
static FrameTarget GetSelectionClosestFrame(nsIFrame* aFrame, nsPoint aPoint,
                                            uint32_t aFlags);

static bool SelfIsSelectable(nsIFrame* aFrame, uint32_t aFlags)
{
  if ((aFlags & nsIFrame::SKIP_HIDDEN) &&
      !aFrame->StyleVisibility()->IsVisible()) {
    return false;
  }
  return !aFrame->IsGeneratedContentFrame() &&
    aFrame->StyleUIReset()->mUserSelect != StyleUserSelect::None;
}

static bool SelectionDescendToKids(nsIFrame* aFrame) {
  StyleUserSelect style = aFrame->StyleUIReset()->mUserSelect;
  nsIFrame* parent = aFrame->GetParent();
  // If we are only near (not directly over) then don't traverse
  // frames with independent selection (e.g. text and list controls)
  // unless we're already inside such a frame (see bug 268497).  Note that this
  // prevents any of the users of this method from entering form controls.
  // XXX We might want some way to allow using the up-arrow to go into a form
  // control, but the focus didn't work right anyway; it'd probably be enough
  // if the left and right arrows could enter textboxes (which I don't believe
  // they can at the moment)
  return !aFrame->IsGeneratedContentFrame() &&
         style != StyleUserSelect::All  &&
         style != StyleUserSelect::None &&
         ((parent->GetStateBits() & NS_FRAME_INDEPENDENT_SELECTION) ||
          !(aFrame->GetStateBits() & NS_FRAME_INDEPENDENT_SELECTION));
}

static FrameTarget GetSelectionClosestFrameForChild(nsIFrame* aChild,
                                                    nsPoint aPoint,
                                                    uint32_t aFlags)
{
  nsIFrame* parent = aChild->GetParent();
  if (SelectionDescendToKids(aChild)) {
    nsPoint pt = aPoint - aChild->GetOffsetTo(parent);
    return GetSelectionClosestFrame(aChild, pt, aFlags);
  }
  return FrameTarget(aChild, false, false);
}

// When the cursor needs to be at the beginning of a block, it shouldn't be
// before the first child.  A click on a block whose first child is a block
// should put the cursor in the child.  The cursor shouldn't be between the
// blocks, because that's not where it's expected.
// Note that this method is guaranteed to succeed.
static FrameTarget DrillDownToSelectionFrame(nsIFrame* aFrame,
                                             bool aEndFrame, uint32_t aFlags) {
  if (SelectionDescendToKids(aFrame)) {
    nsIFrame* result = nullptr;
    nsIFrame *frame = aFrame->PrincipalChildList().FirstChild();
    if (!aEndFrame) {
      while (frame && (!SelfIsSelectable(frame, aFlags) ||
                        frame->IsEmpty()))
        frame = frame->GetNextSibling();
      if (frame)
        result = frame;
    } else {
      // Because the frame tree is singly linked, to find the last frame,
      // we have to iterate through all the frames
      // XXX I have a feeling this could be slow for long blocks, although
      //     I can't find any slowdowns
      while (frame) {
        if (!frame->IsEmpty() && SelfIsSelectable(frame, aFlags))
          result = frame;
        frame = frame->GetNextSibling();
      }
    }
    if (result)
      return DrillDownToSelectionFrame(result, aEndFrame, aFlags);
  }
  // If the current frame has no targetable children, target the current frame
  return FrameTarget(aFrame, true, aEndFrame);
}

// This method finds the closest valid FrameTarget on a given line; if there is
// no valid FrameTarget on the line, it returns a null FrameTarget
static FrameTarget GetSelectionClosestFrameForLine(
                      nsBlockFrame* aParent,
                      nsBlockFrame::LineIterator aLine,
                      nsPoint aPoint,
                      uint32_t aFlags)
{
  nsIFrame *frame = aLine->mFirstChild;
  // Account for end of lines (any iterator from the block is valid)
  if (aLine == aParent->LinesEnd())
    return DrillDownToSelectionFrame(aParent, true, aFlags);
  nsIFrame *closestFromIStart = nullptr, *closestFromIEnd = nullptr;
  nscoord closestIStart = aLine->IStart(), closestIEnd = aLine->IEnd();
  WritingMode wm = aLine->mWritingMode;
  LogicalPoint pt(wm, aPoint, aLine->mContainerSize);
  bool canSkipBr = false;
  for (int32_t n = aLine->GetChildCount(); n;
       --n, frame = frame->GetNextSibling()) {
    // Skip brFrames. Can only skip if the line contains at least
    // one selectable and non-empty frame before
    if (!SelfIsSelectable(frame, aFlags) || frame->IsEmpty() ||
        (canSkipBr && frame->IsBrFrame())) {
      continue;
    }
    canSkipBr = true;
    LogicalRect frameRect = LogicalRect(wm, frame->GetRect(),
                                        aLine->mContainerSize);
    if (pt.I(wm) >= frameRect.IStart(wm)) {
      if (pt.I(wm) < frameRect.IEnd(wm)) {
        return GetSelectionClosestFrameForChild(frame, aPoint, aFlags);
      }
      if (frameRect.IEnd(wm) >= closestIStart) {
        closestFromIStart = frame;
        closestIStart = frameRect.IEnd(wm);
      }
    } else {
      if (frameRect.IStart(wm) <= closestIEnd) {
        closestFromIEnd = frame;
        closestIEnd = frameRect.IStart(wm);
      }
    }
  }
  if (!closestFromIStart && !closestFromIEnd) {
    // We should only get here if there are no selectable frames on a line
    // XXX Do we need more elaborate handling here?
    return FrameTarget::Null();
  }
  if (closestFromIStart &&
      (!closestFromIEnd ||
       (abs(pt.I(wm) - closestIStart) <= abs(pt.I(wm) - closestIEnd)))) {
    return GetSelectionClosestFrameForChild(closestFromIStart, aPoint,
                                            aFlags);
  }
  return GetSelectionClosestFrameForChild(closestFromIEnd, aPoint, aFlags);
}

// This method is for the special handling we do for block frames; they're
// special because they represent paragraphs and because they are organized
// into lines, which have bounds that are not stored elsewhere in the
// frame tree.  Returns a null FrameTarget for frames which are not
// blocks or blocks with no lines except editable one.
static FrameTarget GetSelectionClosestFrameForBlock(nsIFrame* aFrame,
                                                    nsPoint aPoint,
                                                    uint32_t aFlags)
{
  nsBlockFrame* bf = nsLayoutUtils::GetAsBlock(aFrame); // used only for QI
  if (!bf)
    return FrameTarget::Null();

  // This code searches for the correct line
  nsBlockFrame::LineIterator firstLine = bf->LinesBegin();
  nsBlockFrame::LineIterator end = bf->LinesEnd();
  if (firstLine == end) {
    nsIContent *blockContent = aFrame->GetContent();
    if (blockContent) {
      // Return with empty flag true.
      return FrameTarget(aFrame, false, false, true);
    }
    return FrameTarget::Null();
  }
  nsBlockFrame::LineIterator curLine = firstLine;
  nsBlockFrame::LineIterator closestLine = end;
  // Convert aPoint into a LogicalPoint in the writing-mode of this block
  WritingMode wm = curLine->mWritingMode;
  LogicalPoint pt(wm, aPoint, curLine->mContainerSize);
  while (curLine != end) {
    // Check to see if our point lies within the line's block-direction bounds
    nscoord BCoord = pt.B(wm) - curLine->BStart();
    nscoord BSize = curLine->BSize();
    if (BCoord >= 0 && BCoord < BSize) {
      closestLine = curLine;
      break; // We found the line; stop looking
    }
    if (BCoord < 0)
      break;
    ++curLine;
  }

  if (closestLine == end) {
    nsBlockFrame::LineIterator prevLine = curLine.prev();
    nsBlockFrame::LineIterator nextLine = curLine;
    // Avoid empty lines
    while (nextLine != end && nextLine->IsEmpty())
      ++nextLine;
    while (prevLine != end && prevLine->IsEmpty())
      --prevLine;

    // This hidden pref dictates whether a point above or below all lines comes
    // up with a line or the beginning or end of the frame; 0 on Windows,
    // 1 on other platforms by default at the writing of this code
    int32_t dragOutOfFrame =
      Preferences::GetInt("browser.drag_out_of_frame_style");

    if (prevLine == end) {
      if (dragOutOfFrame == 1 || nextLine == end)
        return DrillDownToSelectionFrame(aFrame, false, aFlags);
      closestLine = nextLine;
    } else if (nextLine == end) {
      if (dragOutOfFrame == 1)
        return DrillDownToSelectionFrame(aFrame, true, aFlags);
      closestLine = prevLine;
    } else { // Figure out which line is closer
      if (pt.B(wm) - prevLine->BEnd() < nextLine->BStart() - pt.B(wm))
        closestLine = prevLine;
      else
        closestLine = nextLine;
    }
  }

  do {
    FrameTarget target = GetSelectionClosestFrameForLine(bf, closestLine,
                                                         aPoint, aFlags);
    if (!target.IsNull())
      return target;
    ++closestLine;
  } while (closestLine != end);
  // Fall back to just targeting the last targetable place
  return DrillDownToSelectionFrame(aFrame, true, aFlags);
}

// GetSelectionClosestFrame is the helper function that calculates the closest
// frame to the given point.
// It doesn't completely account for offset styles, so needs to be used in
// restricted environments.
// Cannot handle overlapping frames correctly, so it should receive the output
// of GetFrameForPoint
// Guaranteed to return a valid FrameTarget
static FrameTarget GetSelectionClosestFrame(nsIFrame* aFrame, nsPoint aPoint,
                                            uint32_t aFlags)
{
  {
    // Handle blocks; if the frame isn't a block, the method fails
    FrameTarget target = GetSelectionClosestFrameForBlock(aFrame, aPoint, aFlags);
    if (!target.IsNull())
      return target;
  }

  nsIFrame *kid = aFrame->PrincipalChildList().FirstChild();

  if (kid) {
    // Go through all the child frames to find the closest one
    nsIFrame::FrameWithDistance closest = { nullptr, nscoord_MAX, nscoord_MAX };
    for (; kid; kid = kid->GetNextSibling()) {
      if (!SelfIsSelectable(kid, aFlags) || kid->IsEmpty())
        continue;

      kid->FindCloserFrameForSelection(aPoint, &closest);
    }
    if (closest.mFrame) {
      if (nsSVGUtils::IsInSVGTextSubtree(closest.mFrame))
        return FrameTarget(closest.mFrame, false, false);
      return GetSelectionClosestFrameForChild(closest.mFrame, aPoint, aFlags);
    }
  }
  return FrameTarget(aFrame, false, false);
}

nsIFrame::ContentOffsets OffsetsForSingleFrame(nsIFrame* aFrame, nsPoint aPoint)
{
  nsIFrame::ContentOffsets offsets;
  FrameContentRange range = GetRangeForFrame(aFrame);
  offsets.content = range.content;
  // If there are continuations (meaning it's not one rectangle), this is the
  // best this function can do
  if (aFrame->GetNextContinuation() || aFrame->GetPrevContinuation()) {
    offsets.offset = range.start;
    offsets.secondaryOffset = range.end;
    offsets.associate = CARET_ASSOCIATE_AFTER;
    return offsets;
  }

  // Figure out whether the offsets should be over, after, or before the frame
  nsRect rect(nsPoint(0, 0), aFrame->GetSize());

  bool isBlock = aFrame->GetDisplay() != StyleDisplay::Inline;
  bool isRtl = (aFrame->StyleVisibility()->mDirection == NS_STYLE_DIRECTION_RTL);
  if ((isBlock && rect.y < aPoint.y) ||
      (!isBlock && ((isRtl  && rect.x + rect.width / 2 > aPoint.x) || 
                    (!isRtl && rect.x + rect.width / 2 < aPoint.x)))) {
    offsets.offset = range.end;
    if (rect.Contains(aPoint))
      offsets.secondaryOffset = range.start;
    else
      offsets.secondaryOffset = range.end;
  } else {
    offsets.offset = range.start;
    if (rect.Contains(aPoint))
      offsets.secondaryOffset = range.end;
    else
      offsets.secondaryOffset = range.start;
  }
  offsets.associate =
      offsets.offset == range.start ? CARET_ASSOCIATE_AFTER : CARET_ASSOCIATE_BEFORE;
  return offsets;
}

static nsIFrame* AdjustFrameForSelectionStyles(nsIFrame* aFrame) {
  nsIFrame* adjustedFrame = aFrame;
  for (nsIFrame* frame = aFrame; frame; frame = frame->GetParent())
  {
    // These are the conditions that make all children not able to handle
    // a cursor.
    StyleUserSelect userSelect = frame->StyleUIReset()->mUserSelect;
    if (userSelect == StyleUserSelect::MozText) {
      // If we see a -moz-text element, we shouldn't look further up the parent
      // chain!
      break;
    }
    if (userSelect == StyleUserSelect::All ||
        frame->IsGeneratedContentFrame()) {
      adjustedFrame = frame;
    }
  }
  return adjustedFrame;
}

nsIFrame::ContentOffsets nsIFrame::GetContentOffsetsFromPoint(nsPoint aPoint,
                                                              uint32_t aFlags)
{
  nsIFrame *adjustedFrame;
  if (aFlags & IGNORE_SELECTION_STYLE) {
    adjustedFrame = this;
  }
  else {
    // This section of code deals with special selection styles.  Note that
    // -moz-all exists, even though it doesn't need to be explicitly handled.
    //
    // The offset is forced not to end up in generated content; content offsets
    // cannot represent content outside of the document's content tree.

    adjustedFrame = AdjustFrameForSelectionStyles(this);

    // -moz-user-select: all needs special handling, because clicking on it
    // should lead to the whole frame being selected
    if (adjustedFrame && adjustedFrame->StyleUIReset()->mUserSelect ==
        StyleUserSelect::All) {
      nsPoint adjustedPoint = aPoint + this->GetOffsetTo(adjustedFrame);
      return OffsetsForSingleFrame(adjustedFrame, adjustedPoint);
    }

    // For other cases, try to find a closest frame starting from the parent of
    // the unselectable frame
    if (adjustedFrame != this)
      adjustedFrame = adjustedFrame->GetParent();
  }

  nsPoint adjustedPoint = aPoint + this->GetOffsetTo(adjustedFrame);

  FrameTarget closest =
    GetSelectionClosestFrame(adjustedFrame, adjustedPoint, aFlags);

  if (closest.emptyBlock) {
    ContentOffsets offsets;
    NS_ASSERTION(closest.frame,
                 "closest.frame must not be null when it's empty");
    offsets.content = closest.frame->GetContent();
    offsets.offset = 0;
    offsets.secondaryOffset = 0;
    offsets.associate = CARET_ASSOCIATE_AFTER;
    return offsets;
  }

  // If the correct offset is at one end of a frame, use offset-based
  // calculation method
  if (closest.frameEdge) {
    ContentOffsets offsets;
    FrameContentRange range = GetRangeForFrame(closest.frame);
    offsets.content = range.content;
    if (closest.afterFrame)
      offsets.offset = range.end;
    else
      offsets.offset = range.start;
    offsets.secondaryOffset = offsets.offset;
    offsets.associate = offsets.offset == range.start ?
        CARET_ASSOCIATE_AFTER : CARET_ASSOCIATE_BEFORE;
    return offsets;
  }

  nsPoint pt;
  if (closest.frame != this) {
    if (nsSVGUtils::IsInSVGTextSubtree(closest.frame)) {
      pt = nsLayoutUtils::TransformAncestorPointToFrame(closest.frame,
                                                        aPoint, this);
    } else {
      pt = aPoint - closest.frame->GetOffsetTo(this);
    }
  } else {
    pt = aPoint;
  }
  return static_cast<nsFrame*>(closest.frame)->CalcContentOffsetsFromFramePoint(pt);

  // XXX should I add some kind of offset standardization?
  // consider <b>xxxxx</b><i>zzzzz</i>; should any click between the last
  // x and first z put the cursor in the same logical position in addition
  // to the same visual position?
}

nsIFrame::ContentOffsets nsFrame::CalcContentOffsetsFromFramePoint(nsPoint aPoint)
{
  return OffsetsForSingleFrame(this, aPoint);
}

void
nsIFrame::AssociateImage(const nsStyleImage& aImage, nsPresContext* aPresContext)
{
  if (aImage.GetType() != eStyleImageType_Image) {
    return;
  }

  imgRequestProxy* req = aImage.GetImageData();
  if (!req) {
    return;
  }

  mozilla::css::ImageLoader* loader =
    aPresContext->Document()->StyleImageLoader();

  // If this fails there's not much we can do ...
  loader->AssociateRequestToFrame(req, this);
}

nsresult
nsFrame::GetCursor(const nsPoint& aPoint,
                   nsIFrame::Cursor& aCursor)
{
  FillCursorInformationFromStyle(StyleUserInterface(), aCursor);
  if (NS_STYLE_CURSOR_AUTO == aCursor.mCursor) {
    // If this is editable, I-beam cursor is better for most elements.
    aCursor.mCursor =
      (mContent && mContent->IsEditable())
      ? NS_STYLE_CURSOR_TEXT : NS_STYLE_CURSOR_DEFAULT;
  }
  if (NS_STYLE_CURSOR_TEXT == aCursor.mCursor &&
      GetWritingMode().IsVertical()) {
    // Per CSS UI spec, UA may treat value 'text' as
    // 'vertical-text' for vertical text.
    aCursor.mCursor = NS_STYLE_CURSOR_VERTICAL_TEXT;
  }

  return NS_OK;
}

// Resize and incremental reflow

/* virtual */ void
nsFrame::MarkIntrinsicISizesDirty()
{
  // This version is meant only for what used to be box-to-block adaptors.
  // It should not be called by other derived classes.
  if (::IsXULBoxWrapped(this)) {
    nsBoxLayoutMetrics *metrics = BoxMetrics();

    SizeNeedsRecalc(metrics->mPrefSize);
    SizeNeedsRecalc(metrics->mMinSize);
    SizeNeedsRecalc(metrics->mMaxSize);
    SizeNeedsRecalc(metrics->mBlockPrefSize);
    SizeNeedsRecalc(metrics->mBlockMinSize);
    CoordNeedsRecalc(metrics->mFlex);
    CoordNeedsRecalc(metrics->mAscent);
  }

  if (GetStateBits() & NS_FRAME_FONT_INFLATION_FLOW_ROOT) {
    nsFontInflationData::MarkFontInflationDataTextDirty(this);
  }
}

/* virtual */ nscoord
nsFrame::GetMinISize(nsRenderingContext *aRenderingContext)
{
  nscoord result = 0;
  DISPLAY_MIN_WIDTH(this, result);
  return result;
}

/* virtual */ nscoord
nsFrame::GetPrefISize(nsRenderingContext *aRenderingContext)
{
  nscoord result = 0;
  DISPLAY_PREF_WIDTH(this, result);
  return result;
}

/* virtual */ void
nsFrame::AddInlineMinISize(nsRenderingContext* aRenderingContext,
                           nsIFrame::InlineMinISizeData* aData)
{
  nscoord isize = nsLayoutUtils::IntrinsicForContainer(aRenderingContext,
                    this, nsLayoutUtils::MIN_ISIZE);
  aData->DefaultAddInlineMinISize(this, isize);
}

/* virtual */ void
nsFrame::AddInlinePrefISize(nsRenderingContext* aRenderingContext,
                            nsIFrame::InlinePrefISizeData* aData)
{
  nscoord isize = nsLayoutUtils::IntrinsicForContainer(aRenderingContext,
                    this, nsLayoutUtils::PREF_ISIZE);
  aData->DefaultAddInlinePrefISize(isize);
}

void
nsIFrame::InlineMinISizeData::DefaultAddInlineMinISize(nsIFrame* aFrame,
                                                       nscoord   aISize,
                                                       bool      aAllowBreak)
{
  auto parent = aFrame->GetParent();
  MOZ_ASSERT(parent, "Must have a parent if we get here!");
  const bool mayBreak = aAllowBreak &&
    !aFrame->CanContinueTextRun() &&
    !parent->StyleContext()->ShouldSuppressLineBreak() &&
    parent->StyleText()->WhiteSpaceCanWrap(parent);
  if (mayBreak) {
    OptionallyBreak();
  }
  mTrailingWhitespace = 0;
  mSkipWhitespace = false;
  mCurrentLine += aISize;
  mAtStartOfLine = false;
  if (mayBreak) {
    OptionallyBreak();
  }
}

void
nsIFrame::InlinePrefISizeData::DefaultAddInlinePrefISize(nscoord aISize)
{
  mCurrentLine = NSCoordSaturatingAdd(mCurrentLine, aISize);
  mTrailingWhitespace = 0;
  mSkipWhitespace = false;
  mLineIsEmpty = false;
}

void
nsIFrame::InlineMinISizeData::ForceBreak()
{
  mCurrentLine -= mTrailingWhitespace;
  mPrevLines = std::max(mPrevLines, mCurrentLine);
  mCurrentLine = mTrailingWhitespace = 0;

  for (uint32_t i = 0, i_end = mFloats.Length(); i != i_end; ++i) {
    nscoord float_min = mFloats[i].Width();
    if (float_min > mPrevLines)
      mPrevLines = float_min;
  }
  mFloats.Clear();
  mSkipWhitespace = true;
}

void
nsIFrame::InlineMinISizeData::OptionallyBreak(nscoord aHyphenWidth)
{
  // If we can fit more content into a smaller width by staying on this
  // line (because we're still at a negative offset due to negative
  // text-indent or negative margin), don't break.  Otherwise, do the
  // same as ForceBreak.  it doesn't really matter when we accumulate
  // floats.
  if (mCurrentLine + aHyphenWidth < 0 || mAtStartOfLine)
    return;
  mCurrentLine += aHyphenWidth;
  ForceBreak();
}

void
nsIFrame::InlinePrefISizeData::ForceBreak(StyleClear aBreakType)
{
  MOZ_ASSERT(aBreakType == StyleClear::None ||
             aBreakType == StyleClear::Both ||
             aBreakType == StyleClear::Left ||
             aBreakType == StyleClear::Right,
             "Must be a physical break type");

  // If this force break is not clearing any float, we can leave all the
  // floats to the next force break.
  if (mFloats.Length() != 0 && aBreakType != StyleClear::None) {
            // preferred widths accumulated for floats that have already
            // been cleared past
    nscoord floats_done = 0,
            // preferred widths accumulated for floats that have not yet
            // been cleared past
            floats_cur_left = 0,
            floats_cur_right = 0;
    const WritingMode wm = mLineContainerWM;

    for (uint32_t i = 0, i_end = mFloats.Length(); i != i_end; ++i) {
      const FloatInfo& floatInfo = mFloats[i];
      const nsStyleDisplay* floatDisp = floatInfo.Frame()->StyleDisplay();
      StyleClear breakType = floatDisp->PhysicalBreakType(wm);
      if (breakType == StyleClear::Left ||
          breakType == StyleClear::Right ||
          breakType == StyleClear::Both) {
        nscoord floats_cur = NSCoordSaturatingAdd(floats_cur_left,
                                                  floats_cur_right);
        if (floats_cur > floats_done) {
          floats_done = floats_cur;
        }
        if (breakType != StyleClear::Right) {
          floats_cur_left = 0;
        }
        if (breakType != StyleClear::Left) {
          floats_cur_right = 0;
        }
      }

      StyleFloat floatStyle = floatDisp->PhysicalFloats(wm);
      nscoord& floats_cur =
        floatStyle == StyleFloat::Left ? floats_cur_left : floats_cur_right;
      nscoord floatWidth = floatInfo.Width();
      // Negative-width floats don't change the available space so they
      // shouldn't change our intrinsic line width either.
      floats_cur =
        NSCoordSaturatingAdd(floats_cur, std::max(0, floatWidth));
    }

    nscoord floats_cur =
      NSCoordSaturatingAdd(floats_cur_left, floats_cur_right);
    if (floats_cur > floats_done)
      floats_done = floats_cur;

    mCurrentLine = NSCoordSaturatingAdd(mCurrentLine, floats_done);

    if (aBreakType == StyleClear::Both) {
      mFloats.Clear();
    } else {
      // If the break type does not clear all floats, it means there may
      // be some floats whose isize should contribute to the intrinsic
      // isize of the next line. The code here scans the current mFloats
      // and keeps floats which are not cleared by this break. Note that
      // floats may be cleared directly or indirectly. See below.
      nsTArray<FloatInfo> newFloats;
      MOZ_ASSERT(aBreakType == StyleClear::Left ||
                 aBreakType == StyleClear::Right,
                 "Other values should have been handled in other branches");
      StyleFloat clearFloatType =
        aBreakType == StyleClear::Left ? StyleFloat::Left : StyleFloat::Right;
      // Iterate the array in reverse so that we can stop when there are
      // no longer any floats we need to keep. See below.
      for (FloatInfo& floatInfo : Reversed(mFloats)) {
        const nsStyleDisplay* floatDisp = floatInfo.Frame()->StyleDisplay();
        if (floatDisp->PhysicalFloats(wm) != clearFloatType) {
          newFloats.AppendElement(floatInfo);
        } else {
          // This is a float on the side that this break directly clears
          // which means we're not keeping it in mFloats. However, if
          // this float clears floats on the opposite side (via a value
          // of either 'both' or one of 'left'/'right'), any remaining
          // (earlier) floats on that side would be indirectly cleared
          // as well. Thus, we should break out of this loop and stop
          // considering earlier floats to be kept in mFloats.
          StyleClear floatBreakType = floatDisp->PhysicalBreakType(wm);
          if (floatBreakType != aBreakType &&
              floatBreakType != StyleClear::None) {
            break;
          }
        }
      }
      newFloats.Reverse();
      mFloats = Move(newFloats);
    }
  }

  mCurrentLine =
    NSCoordSaturatingSubtract(mCurrentLine, mTrailingWhitespace, nscoord_MAX);
  mPrevLines = std::max(mPrevLines, mCurrentLine);
  mCurrentLine = mTrailingWhitespace = 0;
  mSkipWhitespace = true;
  mLineIsEmpty = true;
}

static void
AddCoord(const nsStyleCoord& aStyle,
         nsIFrame* aFrame,
         nscoord* aCoord, float* aPercent,
         bool aClampNegativeToZero)
{
  switch (aStyle.GetUnit()) {
    case eStyleUnit_Coord: {
      NS_ASSERTION(!aClampNegativeToZero || aStyle.GetCoordValue() >= 0,
                   "unexpected negative value");
      *aCoord += aStyle.GetCoordValue();
      return;
    }
    case eStyleUnit_Percent: {
      NS_ASSERTION(!aClampNegativeToZero || aStyle.GetPercentValue() >= 0.0f,
                   "unexpected negative value");
      *aPercent += aStyle.GetPercentValue();
      return;
    }
    case eStyleUnit_Calc: {
      const nsStyleCoord::Calc *calc = aStyle.GetCalcValue();
      if (aClampNegativeToZero) {
        // This is far from ideal when one is negative and one is positive.
        *aCoord += std::max(calc->mLength, 0);
        *aPercent += std::max(calc->mPercent, 0.0f);
      } else {
        *aCoord += calc->mLength;
        *aPercent += calc->mPercent;
      }
      return;
    }
    default: {
      return;
    }
  }
}

static nsIFrame::IntrinsicISizeOffsetData
IntrinsicSizeOffsets(nsIFrame* aFrame, bool aForISize)
{
  nsIFrame::IntrinsicISizeOffsetData result;
  WritingMode wm = aFrame->GetWritingMode();
  const nsStyleMargin* styleMargin = aFrame->StyleMargin();
  bool verticalAxis = aForISize == wm.IsVertical();
  AddCoord(verticalAxis ? styleMargin->mMargin.GetTop()
                        : styleMargin->mMargin.GetLeft(),
           aFrame, &result.hMargin, &result.hPctMargin,
           false);
  AddCoord(verticalAxis ? styleMargin->mMargin.GetBottom()
                        : styleMargin->mMargin.GetRight(),
           aFrame, &result.hMargin, &result.hPctMargin,
           false);

  const nsStylePadding* stylePadding = aFrame->StylePadding();
  AddCoord(verticalAxis ? stylePadding->mPadding.GetTop()
                        : stylePadding->mPadding.GetLeft(),
           aFrame, &result.hPadding, &result.hPctPadding,
           true);
  AddCoord(verticalAxis ? stylePadding->mPadding.GetBottom()
                        : stylePadding->mPadding.GetRight(),
           aFrame, &result.hPadding, &result.hPctPadding,
           true);

  const nsStyleBorder* styleBorder = aFrame->StyleBorder();
  if (verticalAxis) {
    result.hBorder += styleBorder->GetComputedBorderWidth(eSideTop);
    result.hBorder += styleBorder->GetComputedBorderWidth(eSideBottom);
  } else {
    result.hBorder += styleBorder->GetComputedBorderWidth(eSideLeft);
    result.hBorder += styleBorder->GetComputedBorderWidth(eSideRight);
  }

  const nsStyleDisplay* disp = aFrame->StyleDisplay();
  if (aFrame->IsThemed(disp)) {
    nsPresContext* presContext = aFrame->PresContext();

    nsIntMargin border;
    presContext->GetTheme()->GetWidgetBorder(presContext->DeviceContext(),
                                             aFrame, disp->mAppearance,
                                             &border);
    result.hBorder =
      presContext->DevPixelsToAppUnits(verticalAxis ? border.TopBottom()
                                                    : border.LeftRight());

    nsIntMargin padding;
    if (presContext->GetTheme()->GetWidgetPadding(presContext->DeviceContext(),
                                                  aFrame, disp->mAppearance,
                                                  &padding)) {
      result.hPadding =
        presContext->DevPixelsToAppUnits(verticalAxis ? padding.TopBottom()
                                                      : padding.LeftRight());
      result.hPctPadding = 0;
    }
  }
  return result;
}

/* virtual */ nsIFrame::IntrinsicISizeOffsetData
nsFrame::IntrinsicISizeOffsets()
{
  return IntrinsicSizeOffsets(this, true);
}

nsIFrame::IntrinsicISizeOffsetData
nsIFrame::IntrinsicBSizeOffsets()
{
  return IntrinsicSizeOffsets(this, false);
}

/* virtual */ IntrinsicSize
nsFrame::GetIntrinsicSize()
{
  return IntrinsicSize(); // default is width/height set to eStyleUnit_None
}

/* virtual */ nsSize
nsFrame::GetIntrinsicRatio()
{
  return nsSize(0, 0);
}

/* virtual */
LogicalSize
nsFrame::ComputeSize(nsRenderingContext* aRenderingContext,
                     WritingMode         aWM,
                     const LogicalSize&  aCBSize,
                     nscoord             aAvailableISize,
                     const LogicalSize&  aMargin,
                     const LogicalSize&  aBorder,
                     const LogicalSize&  aPadding,
                     ComputeSizeFlags    aFlags)
{
  MOZ_ASSERT(GetIntrinsicRatio() == nsSize(0,0),
             "Please override this method and call "
             "nsFrame::ComputeSizeWithIntrinsicDimensions instead.");
  LogicalSize result = ComputeAutoSize(aRenderingContext, aWM,
                                       aCBSize, aAvailableISize,
                                       aMargin, aBorder, aPadding,
                                       aFlags);
  const nsStylePosition *stylePos = StylePosition();

  LogicalSize boxSizingAdjust(aWM);
  if (stylePos->mBoxSizing == StyleBoxSizing::Border) {
    boxSizingAdjust = aBorder + aPadding;
  }
  nscoord boxSizingToMarginEdgeISize =
    aMargin.ISize(aWM) + aBorder.ISize(aWM) + aPadding.ISize(aWM) -
    boxSizingAdjust.ISize(aWM);

  const nsStyleCoord* inlineStyleCoord = &stylePos->ISize(aWM);
  const nsStyleCoord* blockStyleCoord = &stylePos->BSize(aWM);

  auto parentFrame = GetParent();
  auto alignCB = parentFrame;
  bool isGridItem = parentFrame && parentFrame->IsGridContainerFrame() &&
                    !(GetStateBits() & NS_FRAME_OUT_OF_FLOW);
  if (parentFrame && parentFrame->IsTableWrapperFrame() && IsTableFrame()) {
    // An inner table frame is sized as a grid item if its table wrapper is,
    // because they actually have the same CB (the wrapper's CB).
    // @see ReflowInput::InitCBReflowInput
    auto tableWrapper = GetParent();
    auto grandParent = tableWrapper->GetParent();
    isGridItem = (grandParent->IsGridContainerFrame() &&
                  !(tableWrapper->GetStateBits() & NS_FRAME_OUT_OF_FLOW));
    if (isGridItem) {
      // When resolving justify/align-self below, we want to use the grid
      // container's justify/align-items value and WritingMode.
      alignCB = grandParent;
    }
  }
  bool isFlexItem = parentFrame && parentFrame->IsFlexContainerFrame() &&
                    !(GetStateBits() & NS_FRAME_OUT_OF_FLOW);
  bool isInlineFlexItem = false;
  if (isFlexItem) {
    // Flex items use their "flex-basis" property in place of their main-size
    // property (e.g. "width") for sizing purposes, *unless* they have
    // "flex-basis:auto", in which case they use their main-size property after
    // all.
    uint32_t flexDirection = GetParent()->StylePosition()->mFlexDirection;
    isInlineFlexItem =
      flexDirection == NS_STYLE_FLEX_DIRECTION_ROW ||
      flexDirection == NS_STYLE_FLEX_DIRECTION_ROW_REVERSE;

    // NOTE: The logic here should match the similar chunk for determining
    // inlineStyleCoord and blockStyleCoord in
    // nsFrame::ComputeSizeWithIntrinsicDimensions().
    const nsStyleCoord* flexBasis = &(stylePos->mFlexBasis);
    if (flexBasis->GetUnit() != eStyleUnit_Auto) {
      if (isInlineFlexItem) {
        inlineStyleCoord = flexBasis;
      } else {
        // One caveat for vertical flex items: We don't support enumerated
        // values (e.g. "max-content") for height properties yet. So, if our
        // computed flex-basis is an enumerated value, we'll just behave as if
        // it were "auto", which means "use the main-size property after all"
        // (which is "height", in this case).
        // NOTE: Once we support intrinsic sizing keywords for "height",
        // we should remove this check.
        if (flexBasis->GetUnit() != eStyleUnit_Enumerated) {
          blockStyleCoord = flexBasis;
        }
      }
    }
  }

  // Compute inline-axis size

  if (inlineStyleCoord->GetUnit() != eStyleUnit_Auto) {
    result.ISize(aWM) =
      ComputeISizeValue(aRenderingContext, aCBSize.ISize(aWM),
                        boxSizingAdjust.ISize(aWM), boxSizingToMarginEdgeISize,
                        *inlineStyleCoord, aFlags);
  } else if (MOZ_UNLIKELY(isGridItem) &&
             !IS_TRUE_OVERFLOW_CONTAINER(this)) {
    // 'auto' inline-size for grid-level box - fill the CB for 'stretch' /
    // 'normal' and clamp it to the CB if requested:
    bool stretch = false;
    if (!(aFlags & nsIFrame::eShrinkWrap) &&
        !StyleMargin()->HasInlineAxisAuto(aWM)) {
      auto inlineAxisAlignment =
        aWM.IsOrthogonalTo(alignCB->GetWritingMode()) ?
          StylePosition()->UsedAlignSelf(alignCB->StyleContext()) :
          StylePosition()->UsedJustifySelf(alignCB->StyleContext());
      stretch = inlineAxisAlignment == NS_STYLE_ALIGN_NORMAL ||
                inlineAxisAlignment == NS_STYLE_ALIGN_STRETCH;
    }
    if (stretch || (aFlags & ComputeSizeFlags::eIClampMarginBoxMinSize)) {
      auto iSizeToFillCB = std::max(nscoord(0), aCBSize.ISize(aWM) -
                                                aPadding.ISize(aWM) -
                                                aBorder.ISize(aWM) -
                                                aMargin.ISize(aWM));
      if (stretch || result.ISize(aWM) > iSizeToFillCB) {
        result.ISize(aWM) = iSizeToFillCB;
      }
    }
  }

  // Flex items ignore their min & max sizing properties in their
  // flex container's main-axis.  (Those properties get applied later in
  // the flexbox algorithm.)
  const nsStyleCoord& maxISizeCoord = stylePos->MaxISize(aWM);
  nscoord maxISize = NS_UNCONSTRAINEDSIZE;
  if (maxISizeCoord.GetUnit() != eStyleUnit_None &&
      !(isFlexItem && isInlineFlexItem)) {
    maxISize =
      ComputeISizeValue(aRenderingContext, aCBSize.ISize(aWM),
                        boxSizingAdjust.ISize(aWM), boxSizingToMarginEdgeISize,
                        maxISizeCoord, aFlags);
    result.ISize(aWM) = std::min(maxISize, result.ISize(aWM));
  }

  const nsStyleCoord& minISizeCoord = stylePos->MinISize(aWM);
  nscoord minISize;
  if (minISizeCoord.GetUnit() != eStyleUnit_Auto &&
      !(isFlexItem && isInlineFlexItem)) {
    minISize =
      ComputeISizeValue(aRenderingContext, aCBSize.ISize(aWM),
                        boxSizingAdjust.ISize(aWM), boxSizingToMarginEdgeISize,
                        minISizeCoord, aFlags);
  } else if (MOZ_UNLIKELY(aFlags & eIApplyAutoMinSize)) {
    // This implements "Implied Minimum Size of Grid Items".
    // https://drafts.csswg.org/css-grid/#min-size-auto
    minISize = std::min(maxISize, GetMinISize(aRenderingContext));
    if (inlineStyleCoord->IsCoordPercentCalcUnit()) {
      minISize = std::min(minISize, result.ISize(aWM));
    } else if (aFlags & eIClampMarginBoxMinSize) {
      // "if the grid item spans only grid tracks that have a fixed max track
      // sizing function, its automatic minimum size in that dimension is
      // further clamped to less than or equal to the size necessary to fit
      // its margin box within the resulting grid area (flooring at zero)"
      // https://drafts.csswg.org/css-grid/#min-size-auto
      auto maxMinISize = std::max(nscoord(0), aCBSize.ISize(aWM) -
                                              aPadding.ISize(aWM) -
                                              aBorder.ISize(aWM) -
                                              aMargin.ISize(aWM));
      minISize = std::min(minISize, maxMinISize);
    }
  } else {
    // Treat "min-width: auto" as 0.
    // NOTE: Technically, "auto" is supposed to behave like "min-content" on
    // flex items. However, we don't need to worry about that here, because
    // flex items' min-sizes are intentionally ignored until the flex
    // container explicitly considers them during space distribution.
    minISize = 0;
  }
  result.ISize(aWM) = std::max(minISize, result.ISize(aWM));

  // Compute block-axis size
  // (but not if we have auto bsize or if we received the "eUseAutoBSize"
  // flag -- then, we'll just stick with the bsize that we already calculated
  // in the initial ComputeAutoSize() call.)
  if (!(aFlags & nsIFrame::eUseAutoBSize)) {
    if (!nsLayoutUtils::IsAutoBSize(*blockStyleCoord, aCBSize.BSize(aWM))) {
      result.BSize(aWM) =
        nsLayoutUtils::ComputeBSizeValue(aCBSize.BSize(aWM),
                                         boxSizingAdjust.BSize(aWM),
                                         *blockStyleCoord);
    } else if (MOZ_UNLIKELY(isGridItem) &&
               blockStyleCoord->GetUnit() == eStyleUnit_Auto &&
               !IS_TRUE_OVERFLOW_CONTAINER(this)) {
      auto cbSize = aCBSize.BSize(aWM);
      if (cbSize != NS_AUTOHEIGHT) {
        // 'auto' block-size for grid-level box - fill the CB for 'stretch' /
        // 'normal' and clamp it to the CB if requested:
        bool stretch = false;
        if (!StyleMargin()->HasBlockAxisAuto(aWM)) {
          auto blockAxisAlignment =
            !aWM.IsOrthogonalTo(alignCB->GetWritingMode()) ?
              StylePosition()->UsedAlignSelf(alignCB->StyleContext()) :
              StylePosition()->UsedJustifySelf(alignCB->StyleContext());
          stretch = blockAxisAlignment == NS_STYLE_ALIGN_NORMAL ||
                    blockAxisAlignment == NS_STYLE_ALIGN_STRETCH;
        }
        if (stretch || (aFlags & ComputeSizeFlags::eBClampMarginBoxMinSize)) {
          auto bSizeToFillCB = std::max(nscoord(0), cbSize -
                                                    aPadding.BSize(aWM) -
                                                    aBorder.BSize(aWM) -
                                                    aMargin.BSize(aWM));
          if (stretch || (result.BSize(aWM) != NS_AUTOHEIGHT &&
                          result.BSize(aWM) > bSizeToFillCB)) {
            result.BSize(aWM) = bSizeToFillCB;
          }
        }
      }
    }
  }

  const nsStyleCoord& maxBSizeCoord = stylePos->MaxBSize(aWM);

  if (result.BSize(aWM) != NS_UNCONSTRAINEDSIZE) {
    if (!nsLayoutUtils::IsAutoBSize(maxBSizeCoord, aCBSize.BSize(aWM)) &&
        !(isFlexItem && !isInlineFlexItem)) {
      nscoord maxBSize =
        nsLayoutUtils::ComputeBSizeValue(aCBSize.BSize(aWM),
                                         boxSizingAdjust.BSize(aWM),
                                         maxBSizeCoord);
      result.BSize(aWM) = std::min(maxBSize, result.BSize(aWM));
    }

    const nsStyleCoord& minBSizeCoord = stylePos->MinBSize(aWM);

    if (!nsLayoutUtils::IsAutoBSize(minBSizeCoord, aCBSize.BSize(aWM)) &&
        !(isFlexItem && !isInlineFlexItem)) {
      nscoord minBSize =
        nsLayoutUtils::ComputeBSizeValue(aCBSize.BSize(aWM),
                                         boxSizingAdjust.BSize(aWM),
                                         minBSizeCoord);
      result.BSize(aWM) = std::max(minBSize, result.BSize(aWM));
    }
  }

  const nsStyleDisplay *disp = StyleDisplay();
  if (IsThemed(disp)) {
    LayoutDeviceIntSize widget;
    bool canOverride = true;
    nsPresContext *presContext = PresContext();
    presContext->GetTheme()->
      GetMinimumWidgetSize(presContext, this, disp->mAppearance,
                           &widget, &canOverride);

    // Convert themed widget's physical dimensions to logical coords
    LogicalSize size(aWM,
                     nsSize(presContext->DevPixelsToAppUnits(widget.width),
                            presContext->DevPixelsToAppUnits(widget.height)));

    // GMWS() returns border-box; we need content-box
    size.ISize(aWM) -= aBorder.ISize(aWM) + aPadding.ISize(aWM);
    size.BSize(aWM) -= aBorder.BSize(aWM) + aPadding.BSize(aWM);

    if (size.BSize(aWM) > result.BSize(aWM) || !canOverride) {
      result.BSize(aWM) = size.BSize(aWM);
    }
    if (size.ISize(aWM) > result.ISize(aWM) || !canOverride) {
      result.ISize(aWM) = size.ISize(aWM);
    }
  }

  result.ISize(aWM) = std::max(0, result.ISize(aWM));
  result.BSize(aWM) = std::max(0, result.BSize(aWM));

  return result;
}

LogicalSize
nsFrame::ComputeSizeWithIntrinsicDimensions(nsRenderingContext*  aRenderingContext,
                                            WritingMode          aWM,
                                            const IntrinsicSize& aIntrinsicSize,
                                            nsSize               aIntrinsicRatio,
                                            const LogicalSize&   aCBSize,
                                            const LogicalSize&   aMargin,
                                            const LogicalSize&   aBorder,
                                            const LogicalSize&   aPadding,
                                            ComputeSizeFlags     aFlags)
{
  const nsStylePosition* stylePos = StylePosition();
  const nsStyleCoord* inlineStyleCoord = &stylePos->ISize(aWM);
  const nsStyleCoord* blockStyleCoord = &stylePos->BSize(aWM);
  auto* parentFrame = GetParent();
  const bool isGridItem = parentFrame && parentFrame->IsGridContainerFrame() &&
                          !(GetStateBits() & NS_FRAME_OUT_OF_FLOW);
  const bool isFlexItem = parentFrame && parentFrame->IsFlexContainerFrame() &&
                          !(GetStateBits() & NS_FRAME_OUT_OF_FLOW);
  bool isInlineFlexItem = false;
  Maybe<nsStyleCoord> imposedMainSizeStyleCoord;

  // If this is a flex item, and we're measuring its cross size after flexing
  // to resolve its main size, then we need to use the resolved main size
  // that the container provides to us *instead of* the main-size coordinate
  // from our style struct. (Otherwise, we'll be using an irrelevant value in
  // the aspect-ratio calculations below.)
  if (isFlexItem) {
    uint32_t flexDirection =
      GetParent()->StylePosition()->mFlexDirection;
    isInlineFlexItem =
      flexDirection == NS_STYLE_FLEX_DIRECTION_ROW ||
      flexDirection == NS_STYLE_FLEX_DIRECTION_ROW_REVERSE;

    // If FlexItemMainSizeOverride frame-property is set, then that means the
    // flex container is imposing a main-size on this flex item for it to use
    // as its size in the container's main axis.
    bool didImposeMainSize;
    nscoord imposedMainSize =
      GetProperty(nsIFrame::FlexItemMainSizeOverride(), &didImposeMainSize);
    if (didImposeMainSize) {
      imposedMainSizeStyleCoord.emplace(imposedMainSize,
                                        nsStyleCoord::CoordConstructor);
      if (isInlineFlexItem) {
        inlineStyleCoord = imposedMainSizeStyleCoord.ptr();
      } else {
        blockStyleCoord = imposedMainSizeStyleCoord.ptr();
      }

    } else {
      // Flex items use their "flex-basis" property in place of their main-size
      // property (e.g. "width") for sizing purposes, *unless* they have
      // "flex-basis:auto", in which case they use their main-size property
      // after all.
      // NOTE: The logic here should match the similar chunk for determining
      // inlineStyleCoord and blockStyleCoord in nsFrame::ComputeSize().
      const nsStyleCoord* flexBasis = &(stylePos->mFlexBasis);
      if (flexBasis->GetUnit() != eStyleUnit_Auto) {
        if (isInlineFlexItem) {
          inlineStyleCoord = flexBasis;
        } else {
          // One caveat for vertical flex items: We don't support enumerated
          // values (e.g. "max-content") for height properties yet. So, if our
          // computed flex-basis is an enumerated value, we'll just behave as if
          // it were "auto", which means "use the main-size property after all"
          // (which is "height", in this case).
          // NOTE: Once we support intrinsic sizing keywords for "height",
          // we should remove this check.
          if (flexBasis->GetUnit() != eStyleUnit_Enumerated) {
            blockStyleCoord = flexBasis;
          }
        }
      }
    }
  }

  // Handle intrinsic sizes and their interaction with
  // {min-,max-,}{width,height} according to the rules in
  // http://www.w3.org/TR/CSS21/visudet.html#min-max-widths

  // Note: throughout the following section of the function, I avoid
  // a * (b / c) because of its reduced accuracy relative to a * b / c
  // or (a * b) / c (which are equivalent).

  const bool isAutoISize = inlineStyleCoord->GetUnit() == eStyleUnit_Auto;
  const bool isAutoBSize =
    nsLayoutUtils::IsAutoBSize(*blockStyleCoord, aCBSize.BSize(aWM));

  LogicalSize boxSizingAdjust(aWM);
  if (stylePos->mBoxSizing == StyleBoxSizing::Border) {
    boxSizingAdjust = aBorder + aPadding;
  }
  nscoord boxSizingToMarginEdgeISize =
    aMargin.ISize(aWM) + aBorder.ISize(aWM) + aPadding.ISize(aWM) -
      boxSizingAdjust.ISize(aWM);

  nscoord iSize, minISize, maxISize, bSize, minBSize, maxBSize;
  enum class Stretch {
    // stretch to fill the CB (preserving intrinsic ratio) in the relevant axis
    eStretchPreservingRatio, // XXX not used yet
    // stretch to fill the CB in the relevant axis
    eStretch,
    // no stretching in the relevant axis
    eNoStretch,
  };
  // just to avoid having to type these out everywhere:
  const auto eStretchPreservingRatio = Stretch::eStretchPreservingRatio;
  const auto eStretch = Stretch::eStretch;
  const auto eNoStretch = Stretch::eNoStretch;

  Stretch stretchI = eNoStretch; // stretch behavior in the inline axis
  Stretch stretchB = eNoStretch; // stretch behavior in the block axis

  const bool isVertical = aWM.IsVertical();
  const nsStyleCoord& isizeCoord =
    isVertical ? aIntrinsicSize.height : aIntrinsicSize.width;
  const bool hasIntrinsicISize = isizeCoord.GetUnit() == eStyleUnit_Coord;
  nscoord intrinsicISize;
  if (hasIntrinsicISize) {
    intrinsicISize = std::max(nscoord(0), isizeCoord.GetCoordValue());
  } else {
    NS_ASSERTION(isizeCoord.GetUnit() == eStyleUnit_None,
                 "unexpected unit");
    intrinsicISize = 0;
  }

  const nsStyleCoord& bsizeCoord =
    isVertical ? aIntrinsicSize.width : aIntrinsicSize.height;
  const bool hasIntrinsicBSize = bsizeCoord.GetUnit() == eStyleUnit_Coord;
  nscoord intrinsicBSize;
  if (hasIntrinsicBSize) {
    intrinsicBSize = std::max(nscoord(0), bsizeCoord.GetCoordValue());
  } else {
    NS_ASSERTION(bsizeCoord.GetUnit() == eStyleUnit_None,
                 "unexpected unit");
    intrinsicBSize = 0;
  }

  NS_ASSERTION(aIntrinsicRatio.width >= 0 && aIntrinsicRatio.height >= 0,
               "Intrinsic ratio has a negative component!");
  LogicalSize logicalRatio(aWM, aIntrinsicRatio);

  if (!isAutoISize) {
    iSize = ComputeISizeValue(aRenderingContext,
              aCBSize.ISize(aWM), boxSizingAdjust.ISize(aWM),
              boxSizingToMarginEdgeISize, *inlineStyleCoord, aFlags);
  } else if (MOZ_UNLIKELY(isGridItem)) {
    MOZ_ASSERT(!IS_TRUE_OVERFLOW_CONTAINER(this));
    // 'auto' inline-size for grid-level box - apply 'stretch' as needed:
    auto cbSize = aCBSize.ISize(aWM);
    if (cbSize != NS_UNCONSTRAINEDSIZE) {
      if (!StyleMargin()->HasInlineAxisAuto(aWM)) {
        auto inlineAxisAlignment =
          aWM.IsOrthogonalTo(GetParent()->GetWritingMode()) ?
            stylePos->UsedAlignSelf(GetParent()->StyleContext()) :
            stylePos->UsedJustifySelf(GetParent()->StyleContext());
        // Note: 'normal' means 'start' for elements with an intrinsic size
        // or ratio in the relevant dimension, otherwise 'stretch'.
        // https://drafts.csswg.org/css-grid/#grid-item-sizing
        if ((inlineAxisAlignment == NS_STYLE_ALIGN_NORMAL &&
             !hasIntrinsicISize &&
             !(logicalRatio.ISize(aWM) > 0)) ||
            inlineAxisAlignment == NS_STYLE_ALIGN_STRETCH) {
          stretchI = eStretch;
        }
      }
      if (stretchI != eNoStretch ||
          (aFlags & ComputeSizeFlags::eIClampMarginBoxMinSize)) {
        iSize = std::max(nscoord(0), cbSize -
                                     aPadding.ISize(aWM) -
                                     aBorder.ISize(aWM) -
                                     aMargin.ISize(aWM));
      }
    } else {
      // Reset this flag to avoid applying the clamping below.
      aFlags = ComputeSizeFlags(aFlags &
                                ~ComputeSizeFlags::eIClampMarginBoxMinSize);
    }
  }

  const nsStyleCoord& maxISizeCoord = stylePos->MaxISize(aWM);

  if (maxISizeCoord.GetUnit() != eStyleUnit_None &&
      !(isFlexItem && isInlineFlexItem)) {
    maxISize = ComputeISizeValue(aRenderingContext,
                 aCBSize.ISize(aWM), boxSizingAdjust.ISize(aWM),
                 boxSizingToMarginEdgeISize, maxISizeCoord, aFlags);
  } else {
    maxISize = nscoord_MAX;
  }

  // NOTE: Flex items ignore their min & max sizing properties in their
  // flex container's main-axis.  (Those properties get applied later in
  // the flexbox algorithm.)

  const nsStyleCoord& minISizeCoord = stylePos->MinISize(aWM);

  if (minISizeCoord.GetUnit() != eStyleUnit_Auto &&
      !(isFlexItem && isInlineFlexItem)) {
    minISize = ComputeISizeValue(aRenderingContext,
                 aCBSize.ISize(aWM), boxSizingAdjust.ISize(aWM),
                 boxSizingToMarginEdgeISize, minISizeCoord, aFlags);
  } else {
    // Treat "min-width: auto" as 0.
    // NOTE: Technically, "auto" is supposed to behave like "min-content" on
    // flex items. However, we don't need to worry about that here, because
    // flex items' min-sizes are intentionally ignored until the flex
    // container explicitly considers them during space distribution.
    minISize = 0;
  }

  if (!isAutoBSize) {
    bSize = nsLayoutUtils::ComputeBSizeValue(aCBSize.BSize(aWM),
                boxSizingAdjust.BSize(aWM),
                *blockStyleCoord);
  } else if (MOZ_UNLIKELY(isGridItem)) {
    MOZ_ASSERT(!IS_TRUE_OVERFLOW_CONTAINER(this));
    // 'auto' block-size for grid-level box - apply 'stretch' as needed:
    auto cbSize = aCBSize.BSize(aWM);
    if (cbSize != NS_AUTOHEIGHT) {
      if (!StyleMargin()->HasBlockAxisAuto(aWM)) {
        auto blockAxisAlignment =
          !aWM.IsOrthogonalTo(GetParent()->GetWritingMode()) ?
            stylePos->UsedAlignSelf(GetParent()->StyleContext()) :
            stylePos->UsedJustifySelf(GetParent()->StyleContext());
        // Note: 'normal' means 'start' for elements with an intrinsic size
        // or ratio in the relevant dimension, otherwise 'stretch'.
        // https://drafts.csswg.org/css-grid/#grid-item-sizing
        if ((blockAxisAlignment == NS_STYLE_ALIGN_NORMAL &&
             !hasIntrinsicBSize &&
             !(logicalRatio.BSize(aWM) > 0)) ||
            blockAxisAlignment == NS_STYLE_ALIGN_STRETCH) {
          stretchB = eStretch;
        }
      }
      if (stretchB != eNoStretch ||
          (aFlags & ComputeSizeFlags::eBClampMarginBoxMinSize)) {
        bSize = std::max(nscoord(0), cbSize -
                                     aPadding.BSize(aWM) -
                                     aBorder.BSize(aWM) -
                                     aMargin.BSize(aWM));
      }
    } else {
      // Reset this flag to avoid applying the clamping below.
      aFlags = ComputeSizeFlags(aFlags &
                                ~ComputeSizeFlags::eBClampMarginBoxMinSize);
    }
  }

  const nsStyleCoord& maxBSizeCoord = stylePos->MaxBSize(aWM);

  if (!nsLayoutUtils::IsAutoBSize(maxBSizeCoord, aCBSize.BSize(aWM)) &&
      !(isFlexItem && !isInlineFlexItem)) {
    maxBSize = nsLayoutUtils::ComputeBSizeValue(aCBSize.BSize(aWM),
                  boxSizingAdjust.BSize(aWM), maxBSizeCoord);
  } else {
    maxBSize = nscoord_MAX;
  }

  const nsStyleCoord& minBSizeCoord = stylePos->MinBSize(aWM);

  if (!nsLayoutUtils::IsAutoBSize(minBSizeCoord, aCBSize.BSize(aWM)) &&
      !(isFlexItem && !isInlineFlexItem)) {
    minBSize = nsLayoutUtils::ComputeBSizeValue(aCBSize.BSize(aWM),
                  boxSizingAdjust.BSize(aWM), minBSizeCoord);
  } else {
    minBSize = 0;
  }

  NS_ASSERTION(aCBSize.ISize(aWM) != NS_UNCONSTRAINEDSIZE,
               "Our containing block must not have unconstrained inline-size!");

  // Now calculate the used values for iSize and bSize:

  if (isAutoISize) {
    if (isAutoBSize) {

      // 'auto' iSize, 'auto' bSize

      // Get tentative values - CSS 2.1 sections 10.3.2 and 10.6.2:

      nscoord tentISize, tentBSize;

      if (hasIntrinsicISize) {
        tentISize = intrinsicISize;
      } else if (hasIntrinsicBSize && logicalRatio.BSize(aWM) > 0) {
        tentISize = NSCoordMulDiv(intrinsicBSize, logicalRatio.ISize(aWM), logicalRatio.BSize(aWM));
      } else if (logicalRatio.ISize(aWM) > 0) {
        tentISize = aCBSize.ISize(aWM) - boxSizingToMarginEdgeISize; // XXX scrollbar?
        if (tentISize < 0) tentISize = 0;
      } else {
        tentISize = nsPresContext::CSSPixelsToAppUnits(300);
      }

      // If we need to clamp the inline size to fit the CB, we use the 'stretch'
      // or 'normal' codepath.  We use the ratio-preserving 'normal' codepath
      // unless we have 'stretch' in the other axis.
      if ((aFlags & ComputeSizeFlags::eIClampMarginBoxMinSize) &&
          stretchI != eStretch && tentISize > iSize) {
        stretchI = (stretchB == eStretch ? eStretch : eStretchPreservingRatio);
      }

      if (hasIntrinsicBSize) {
        tentBSize = intrinsicBSize;
      } else if (logicalRatio.ISize(aWM) > 0) {
        tentBSize = NSCoordMulDiv(tentISize, logicalRatio.BSize(aWM), logicalRatio.ISize(aWM));
      } else {
        tentBSize = nsPresContext::CSSPixelsToAppUnits(150);
      }

      // (ditto the comment about clamping the inline size above)
      if ((aFlags & ComputeSizeFlags::eBClampMarginBoxMinSize) &&
          stretchB != eStretch && tentBSize > bSize) {
        stretchB = (stretchI == eStretch ? eStretch : eStretchPreservingRatio);
      }

      if (aIntrinsicRatio != nsSize(0, 0)) {
        if (stretchI == eStretch) {
          tentISize = iSize;  // * / 'stretch'
          if (stretchB == eStretch) {
            tentBSize = bSize;  // 'stretch' / 'stretch'
          } else if (stretchB == eStretchPreservingRatio && logicalRatio.ISize(aWM) > 0) {
            // 'normal' / 'stretch'
            tentBSize = NSCoordMulDiv(iSize, logicalRatio.BSize(aWM), logicalRatio.ISize(aWM));
          }
        } else if (stretchB == eStretch) {
          tentBSize = bSize;  // 'stretch' / * (except 'stretch')
          if (stretchI == eStretchPreservingRatio && logicalRatio.BSize(aWM) > 0) {
            // 'stretch' / 'normal'
            tentISize = NSCoordMulDiv(bSize, logicalRatio.ISize(aWM), logicalRatio.BSize(aWM));
          }
        } else if (stretchI == eStretchPreservingRatio) {
          tentISize = iSize;  // * (except 'stretch') / 'normal'
          if (logicalRatio.ISize(aWM) > 0) {
            tentBSize = NSCoordMulDiv(iSize, logicalRatio.BSize(aWM), logicalRatio.ISize(aWM));
          }
          if (stretchB == eStretchPreservingRatio && tentBSize > bSize) {
            // Stretch within the CB size with preserved intrinsic ratio.
            tentBSize = bSize;  // 'normal' / 'normal'
            if (logicalRatio.BSize(aWM) > 0) {
              tentISize = NSCoordMulDiv(bSize, logicalRatio.ISize(aWM), logicalRatio.BSize(aWM));
            }
          }
        } else if (stretchB == eStretchPreservingRatio) {
          tentBSize = bSize;  // 'normal' / * (except 'normal' and 'stretch')
          if (logicalRatio.BSize(aWM) > 0) {
            tentISize = NSCoordMulDiv(bSize, logicalRatio.ISize(aWM), logicalRatio.BSize(aWM));
          }
        }
      }

      // ComputeAutoSizeWithIntrinsicDimensions preserves the ratio when applying
      // the min/max-size.  We don't want that when we have 'stretch' in either
      // axis because tentISize/tentBSize is likely not according to ratio now.
      if (aIntrinsicRatio != nsSize(0, 0) &&
          stretchI != eStretch && stretchB != eStretch) {
        nsSize autoSize = nsLayoutUtils::
          ComputeAutoSizeWithIntrinsicDimensions(minISize, minBSize,
                                                 maxISize, maxBSize,
                                                 tentISize, tentBSize);
        // The nsSize that ComputeAutoSizeWithIntrinsicDimensions returns will
        // actually contain logical values if the parameters passed to it were
        // logical coordinates, so we do NOT perform a physical-to-logical
        // conversion here, but just assign the fields directly to our result.
        iSize = autoSize.width;
        bSize = autoSize.height;
      } else {
        // Not honoring an intrinsic ratio: clamp the dimensions independently.
        iSize = NS_CSS_MINMAX(tentISize, minISize, maxISize);
        bSize = NS_CSS_MINMAX(tentBSize, minBSize, maxBSize);
      }
    } else {

      // 'auto' iSize, non-'auto' bSize
      bSize = NS_CSS_MINMAX(bSize, minBSize, maxBSize);
      if (stretchI != eStretch) {
        if (logicalRatio.BSize(aWM) > 0) {
          iSize = NSCoordMulDiv(bSize, logicalRatio.ISize(aWM), logicalRatio.BSize(aWM));
        } else if (hasIntrinsicISize) {
          if (!((aFlags & ComputeSizeFlags::eIClampMarginBoxMinSize) &&
                intrinsicISize > iSize)) {
            iSize = intrinsicISize;
          } // else - leave iSize as is to fill the CB
        } else {
          iSize = nsPresContext::CSSPixelsToAppUnits(300);
        }
      } // else - leave iSize as is to fill the CB
      iSize = NS_CSS_MINMAX(iSize, minISize, maxISize);

    }
  } else {
    if (isAutoBSize) {

      // non-'auto' iSize, 'auto' bSize
      iSize = NS_CSS_MINMAX(iSize, minISize, maxISize);
      if (stretchB != eStretch) {
        if (logicalRatio.ISize(aWM) > 0) {
          bSize = NSCoordMulDiv(iSize, logicalRatio.BSize(aWM), logicalRatio.ISize(aWM));
        } else if (hasIntrinsicBSize) {
          if (!((aFlags & ComputeSizeFlags::eBClampMarginBoxMinSize) &&
                intrinsicBSize > bSize)) {
            bSize = intrinsicBSize;
          } // else - leave bSize as is to fill the CB
        } else {
          bSize = nsPresContext::CSSPixelsToAppUnits(150);
        }
      } // else - leave bSize as is to fill the CB
      bSize = NS_CSS_MINMAX(bSize, minBSize, maxBSize);

    } else {

      // non-'auto' iSize, non-'auto' bSize
      iSize = NS_CSS_MINMAX(iSize, minISize, maxISize);
      bSize = NS_CSS_MINMAX(bSize, minBSize, maxBSize);

    }
  }

  return LogicalSize(aWM, iSize, bSize);
}

nsRect
nsIFrame::ComputeTightBounds(DrawTarget* aDrawTarget) const
{
  return GetVisualOverflowRect();
}

nsRect
nsFrame::ComputeSimpleTightBounds(DrawTarget* aDrawTarget) const
{
  if (StyleOutline()->ShouldPaintOutline() || StyleBorder()->HasBorder() ||
      !StyleBackground()->IsTransparent(this) ||
      StyleDisplay()->mAppearance) {
    // Not necessarily tight, due to clipping, negative
    // outline-offset, and lots of other issues, but that's OK
    return GetVisualOverflowRect();
  }

  nsRect r(0, 0, 0, 0);
  ChildListIterator lists(this);
  for (; !lists.IsDone(); lists.Next()) {
    nsFrameList::Enumerator childFrames(lists.CurrentList());
    for (; !childFrames.AtEnd(); childFrames.Next()) {
      nsIFrame* child = childFrames.get();
      r.UnionRect(r, child->ComputeTightBounds(aDrawTarget) + child->GetPosition());
    }
  }
  return r;
}

/* virtual */ nsresult
nsIFrame::GetPrefWidthTightBounds(nsRenderingContext* aContext,
                                  nscoord* aX,
                                  nscoord* aXMost)
{
  return NS_ERROR_NOT_IMPLEMENTED;
}

/* virtual */
LogicalSize
nsFrame::ComputeAutoSize(nsRenderingContext*         aRenderingContext,
                         WritingMode                 aWM,
                         const mozilla::LogicalSize& aCBSize,
                         nscoord                     aAvailableISize,
                         const mozilla::LogicalSize& aMargin,
                         const mozilla::LogicalSize& aBorder,
                         const mozilla::LogicalSize& aPadding,
                         ComputeSizeFlags            aFlags)
{
  // Use basic shrink-wrapping as a default implementation.
  LogicalSize result(aWM, 0xdeadbeef, NS_UNCONSTRAINEDSIZE);

  // don't bother setting it if the result won't be used
  if (StylePosition()->ISize(aWM).GetUnit() == eStyleUnit_Auto) {
    nscoord availBased = aAvailableISize - aMargin.ISize(aWM) -
                         aBorder.ISize(aWM) - aPadding.ISize(aWM);
    result.ISize(aWM) = ShrinkWidthToFit(aRenderingContext, availBased, aFlags);
  }
  return result;
}

nscoord
nsFrame::ShrinkWidthToFit(nsRenderingContext* aRenderingContext,
                          nscoord             aISizeInCB,
                          ComputeSizeFlags    aFlags)
{
  // If we're a container for font size inflation, then shrink
  // wrapping inside of us should not apply font size inflation.
  AutoMaybeDisableFontInflation an(this);

  nscoord result;
  nscoord minISize = GetMinISize(aRenderingContext);
  if (minISize > aISizeInCB) {
    const bool clamp = aFlags & ComputeSizeFlags::eIClampMarginBoxMinSize;
    result = MOZ_UNLIKELY(clamp) ? aISizeInCB : minISize;
  } else {
    nscoord prefISize = GetPrefISize(aRenderingContext);
    if (prefISize > aISizeInCB) {
      result = aISizeInCB;
    } else {
      result = prefISize;
    }
  }
  return result;
}

nscoord
nsIFrame::ComputeISizeValue(nsRenderingContext* aRenderingContext,
                            nscoord             aContainingBlockISize,
                            nscoord             aContentEdgeToBoxSizing,
                            nscoord             aBoxSizingToMarginEdge,
                            const nsStyleCoord& aCoord,
                            ComputeSizeFlags    aFlags)
{
  NS_PRECONDITION(aRenderingContext, "non-null rendering context expected");
  LAYOUT_WARN_IF_FALSE(aContainingBlockISize != NS_UNCONSTRAINEDSIZE,
                       "have unconstrained inline-size; this should only result from "
                       "very large sizes, not attempts at intrinsic inline-size "
                       "calculation");
  NS_PRECONDITION(aContainingBlockISize >= 0,
                  "inline-size less than zero");

  nscoord result;
  if (aCoord.IsCoordPercentCalcUnit()) {
    result = nsRuleNode::ComputeCoordPercentCalc(aCoord,
                                                 aContainingBlockISize);
    // The result of a calc() expression might be less than 0; we
    // should clamp at runtime (below).  (Percentages and coords that
    // are less than 0 have already been dropped by the parser.)
    result -= aContentEdgeToBoxSizing;
  } else {
    MOZ_ASSERT(eStyleUnit_Enumerated == aCoord.GetUnit());
    // If 'this' is a container for font size inflation, then shrink
    // wrapping inside of it should not apply font size inflation.
    AutoMaybeDisableFontInflation an(this);

    int32_t val = aCoord.GetIntValue();
    switch (val) {
      case NS_STYLE_WIDTH_MAX_CONTENT:
        result = GetPrefISize(aRenderingContext);
        NS_ASSERTION(result >= 0, "inline-size less than zero");
        break;
      case NS_STYLE_WIDTH_MIN_CONTENT:
        result = GetMinISize(aRenderingContext);
        NS_ASSERTION(result >= 0, "inline-size less than zero");
        if (MOZ_UNLIKELY(aFlags & ComputeSizeFlags::eIClampMarginBoxMinSize)) {
          auto available = aContainingBlockISize -
                           (aBoxSizingToMarginEdge + aContentEdgeToBoxSizing);
          result = std::min(available, result);
        }
        break;
      case NS_STYLE_WIDTH_FIT_CONTENT:
        {
          nscoord pref = GetPrefISize(aRenderingContext),
                   min = GetMinISize(aRenderingContext),
                  fill = aContainingBlockISize -
                         (aBoxSizingToMarginEdge + aContentEdgeToBoxSizing);
          if (MOZ_UNLIKELY(aFlags & ComputeSizeFlags::eIClampMarginBoxMinSize)) {
            min = std::min(min, fill);
          }
          result = std::max(min, std::min(pref, fill));
          NS_ASSERTION(result >= 0, "inline-size less than zero");
        }
        break;
      case NS_STYLE_WIDTH_AVAILABLE:
        result = aContainingBlockISize -