layout/generic/nsBlockFrame.h
author Nika Layzell <nika@thelayzells.com>
Tue, 25 Sep 2018 17:34:53 +0200
changeset 507828 5e6dae0c1e5a4939ccd406f14607f7fafffd45a7
parent 503672 09df5390e2fb01be435bf72a8c8e1c1948e45f62
child 508163 6f3709b3878117466168c40affa7bca0b60cf75b
permissions -rw-r--r--
Bug 1448426 - Wrap windows.h to avoid problematic define statements, r=froydnj,glandium By default, windows.h exposes a large number of problematic define statements which are UpperCamelCase, such as a define from `CreateWindow` to `CreateWindow{A,W}`. As many of these names are generic (e.g. CreateFile, CreateWindow), they can mess up Gecko code that may legitimately have its own methods with the same names. The header also defines some traditional SCREAMING_SNAKE_CASE defines which can mess up our code by conflicting with local values. This patch adds a simple code generator which generates wrappers for these defines, and uses them to wrap the windows.h wrapper using the `stl_wrappers` mechanism, allowing us to use windows.h in more places. Differential Revision: https://phabricator.services.mozilla.com/D10932

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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/. */

/*
 * rendering object for CSS display:block, inline-block, and list-item
 * boxes, also used for various anonymous boxes
 */

#ifndef nsBlockFrame_h___
#define nsBlockFrame_h___

#include "nsContainerFrame.h"
#include "nsHTMLParts.h"
#include "nsLineBox.h"
#include "nsCSSPseudoElements.h"
#include "nsFloatManager.h"

enum class LineReflowStatus {
  // The line was completely reflowed and fit in available width, and we should
  // try to pull up content from the next line if possible.
  OK,
  // The line was completely reflowed and fit in available width, but we should
  // not try to pull up content from the next line.
  Stop,
  // We need to reflow the line again at its current vertical position. The
  // new reflow should not try to pull up any frames from the next line.
  RedoNoPull,
  // We need to reflow the line again using the floats from its height
  // this reflow, since its height made it hit floats that were not
  // adjacent to its top.
  RedoMoreFloats,
  // We need to reflow the line again at a lower vertical postion where there
  // may be more horizontal space due to different float configuration.
  RedoNextBand,
  // The line did not fit in the available vertical space. Try pushing it to
  // the next page or column if it's not the first line on the current page/column.
  Truncated
};

class nsBlockInFlowLineIterator;
class nsBulletFrame;
namespace mozilla {
class BlockReflowInput;
class ServoRestyleState;
class ServoStyleSet;
} // namespace mozilla

/**
 * Some invariants:
 * -- The overflow out-of-flows list contains the out-of-
 * flow frames whose placeholders are in the overflow list.
 * -- A given piece of content has at most one placeholder
 * frame in a block's normal child list.
 * -- While a block is being reflowed, and from then until
 * its next-in-flow is reflowed it may have a
 * PushedFloatProperty frame property that points to
 * an nsFrameList. This list contains continuations for
 * floats whose prev-in-flow is in the block's regular float
 * list and first-in-flows of floats that did not fit, but
 * whose placeholders are in the block or one of its
 * prev-in-flows.
 * -- In all these frame lists, if there are two frames for
 * the same content appearing in the list, then the frames
 * appear with the prev-in-flow before the next-in-flow.
 * -- While reflowing a block, its overflow line list
 * will usually be empty but in some cases will have lines
 * (while we reflow the block at its shrink-wrap width).
 * In this case any new overflowing content must be
 * prepended to the overflow lines.
 */

/*
 * Base class for block and inline frames.
 * The block frame has an additional child list, kAbsoluteList, which
 * contains the absolutely positioned frames.
 */
class nsBlockFrame : public nsContainerFrame
{
  using BlockReflowInput = mozilla::BlockReflowInput;

public:
  NS_DECL_FRAMEARENA_HELPERS(nsBlockFrame)

  typedef nsLineList::iterator LineIterator;
  typedef nsLineList::const_iterator ConstLineIterator;
  typedef nsLineList::reverse_iterator ReverseLineIterator;
  typedef nsLineList::const_reverse_iterator ConstReverseLineIterator;

  LineIterator LinesBegin() { return mLines.begin(); }
  LineIterator LinesEnd() { return mLines.end(); }
  ConstLineIterator LinesBegin() const { return mLines.begin(); }
  ConstLineIterator LinesEnd() const { return mLines.end(); }
  ReverseLineIterator LinesRBegin() { return mLines.rbegin(); }
  ReverseLineIterator LinesREnd() { return mLines.rend(); }
  ConstReverseLineIterator LinesRBegin() const { return mLines.rbegin(); }
  ConstReverseLineIterator LinesREnd() const { return mLines.rend(); }
  LineIterator LinesBeginFrom(nsLineBox* aList) { return mLines.begin(aList); }
  ReverseLineIterator LinesRBeginFrom(nsLineBox* aList) { return mLines.rbegin(aList); }

  friend nsBlockFrame* NS_NewBlockFrame(nsIPresShell* aPresShell,
                                        ComputedStyle* aStyle);

  // nsQueryFrame
  NS_DECL_QUERYFRAME

  // nsIFrame
  void Init(nsIContent* aContent,
            nsContainerFrame* aParent,
            nsIFrame* aPrevInFlow) override;
  void SetInitialChildList(ChildListID aListID,
                           nsFrameList& aChildList) override;
  void AppendFrames(ChildListID aListID,
                    nsFrameList& aFrameList) override;
  void InsertFrames(ChildListID aListID,
                    nsIFrame* aPrevFrame,
                    nsFrameList& aFrameList) override;
  void RemoveFrame(ChildListID aListID,
                   nsIFrame* aOldFrame) override;
  const nsFrameList& GetChildList(ChildListID aListID) const override;
  void GetChildLists(nsTArray<ChildList>* aLists) const override;
  nscoord GetLogicalBaseline(mozilla::WritingMode aWritingMode) const override;
  bool GetVerticalAlignBaseline(mozilla::WritingMode aWM,
                                nscoord* aBaseline) const override
  {
    nscoord lastBaseline;
    if (GetNaturalBaselineBOffset(aWM, BaselineSharingGroup::eLast, &lastBaseline)) {
      *aBaseline = BSize() - lastBaseline;
      return true;
    }
    return false;
  }
  bool GetNaturalBaselineBOffset(mozilla::WritingMode aWM,
                                 BaselineSharingGroup aBaselineGroup,
                                 nscoord*             aBaseline) const override;
  nscoord GetCaretBaseline() const override;
  void DestroyFrom(nsIFrame* aDestructRoot, PostDestroyData& aPostDestroyData) override;
  bool IsFloatContainingBlock() const override;
  void BuildDisplayList(nsDisplayListBuilder* aBuilder,
                        const nsDisplayListSet& aLists) override;
  bool IsFrameOfType(uint32_t aFlags) const override
  {
    return nsContainerFrame::IsFrameOfType(aFlags &
             ~(nsIFrame::eCanContainOverflowContainers |
               nsIFrame::eBlockFrame));
  }

  void InvalidateFrame(uint32_t aDisplayItemKey = 0, bool aRebuildDisplayItems = true) override;
  void InvalidateFrameWithRect(const nsRect& aRect, uint32_t aDisplayItemKey = 0, bool aRebuildDisplayItems = true) override;

#ifdef DEBUG_FRAME_DUMP
  void List(FILE* out = stderr, const char* aPrefix = "", uint32_t aFlags = 0) const override;
  nsresult GetFrameName(nsAString& aResult) const override;
#endif

#ifdef DEBUG
  const char* LineReflowStatusToString(LineReflowStatus aLineReflowStatus) const;
#endif

#ifdef ACCESSIBILITY
  mozilla::a11y::AccType AccessibleType() override;
#endif

  // Line cursor methods to speed up line searching in which one query
  // result is expected to be close to the next in general. This is
  // mainly for searching line(s) containing a point. It is also used
  // as a cache for local computation. Use AutoLineCursorSetup for the
  // latter case so that it wouldn't interact unexpectedly with the
  // former. The basic idea for the former is that we set the cursor
  // property if the lines' overflowArea.VisualOverflow().ys and
  // overflowArea.VisualOverflow().yMosts are non-decreasing
  // (considering only non-empty overflowArea.VisualOverflow()s; empty
  // overflowArea.VisualOverflow()s never participate in event handling
  // or painting), and the block has sufficient number of lines. The
  // cursor property points to a "recently used" line. If we get a
  // series of requests that work on lines
  // "near" the cursor, then we can find those nearby lines quickly by
  // starting our search at the cursor.

  // Clear out line cursor because we're disturbing the lines (i.e., Reflow)
  void ClearLineCursor();
  // Get the first line that might contain y-coord 'y', or nullptr if you must search
  // all lines. If nonnull is returned then we guarantee that the lines'
  // combinedArea.ys and combinedArea.yMosts are non-decreasing.
  // The actual line returned might not contain 'y', but if not, it is guaranteed
  // to be before any line which does contain 'y'.
  nsLineBox* GetFirstLineContaining(nscoord y);
  // Set the line cursor to our first line. Only call this if you
  // guarantee that either the lines' combinedArea.ys and combinedArea.
  // yMosts are non-decreasing, or the line cursor is cleared before
  // building the display list of this frame.
  void SetupLineCursor();

  /**
   * Helper RAII class for automatically set and clear line cursor for
   * temporary use. If the frame already has line cursor, this would be
   * a no-op.
   */
  class MOZ_STACK_CLASS AutoLineCursorSetup
  {
  public:
    explicit AutoLineCursorSetup(nsBlockFrame* aFrame)
      : mFrame(aFrame)
      , mOrigCursor(aFrame->GetLineCursor())
    {
      if (!mOrigCursor) {
        mFrame->SetupLineCursor();
      }
    }
    ~AutoLineCursorSetup()
    {
      if (mOrigCursor) {
        mFrame->SetProperty(LineCursorProperty(), mOrigCursor);
      } else {
        mFrame->ClearLineCursor();
      }
    }

  private:
    nsBlockFrame* mFrame;
    nsLineBox* mOrigCursor;
  };

  void ChildIsDirty(nsIFrame* aChild) override;
  bool IsVisibleInSelection(mozilla::dom::Selection* aSelection) override;

  bool IsEmpty() override;
  bool CachedIsEmpty() override;
  bool IsSelfEmpty() override;

  // Given that we have a bullet, does it actually draw something, i.e.,
  // do we have either a 'list-style-type' or 'list-style-image' that is
  // not 'none'?
  bool BulletIsEmpty() const;

  /**
   * Return the bullet text equivalent.
   */
  void GetSpokenBulletText(nsAString& aText) const;

  /**
   * Return true if there's a bullet.
   */
  bool HasBullet() const {
    return HasOutsideBullet() || HasInsideBullet();
  }

  /**
   * @return true if this frame has an inside bullet frame.
   */
  bool HasInsideBullet() const {
    return 0 != (mState & NS_BLOCK_FRAME_HAS_INSIDE_BULLET);
  }

  /**
   * @return true if this frame has an outside bullet frame.
   */
  bool HasOutsideBullet() const {
    return 0 != (mState & NS_BLOCK_FRAME_HAS_OUTSIDE_BULLET);
  }

  /**
   * @return the bullet frame or nullptr if we don't have one.
   */
  nsBulletFrame* GetBullet() const {
    nsBulletFrame* outside = GetOutsideBullet();
    return outside ? outside : GetInsideBullet();
  }

  /**
   * @return the first-letter frame or nullptr if we don't have one.
   */
  nsIFrame* GetFirstLetter() const;

  /**
   * @return the ::first-line frame or nullptr if we don't have one.
   */
  nsIFrame* GetFirstLineFrame() const;

  void MarkIntrinsicISizesDirty() override;
private:
  void CheckIntrinsicCacheAgainstShrinkWrapState();
public:
  nscoord GetMinISize(gfxContext *aRenderingContext) override;
  nscoord GetPrefISize(gfxContext *aRenderingContext) override;

  nsRect ComputeTightBounds(DrawTarget* aDrawTarget) const override;

  nsresult GetPrefWidthTightBounds(gfxContext* aContext,
                                   nscoord* aX,
                                   nscoord* aXMost) override;

  /**
   * Compute the final block size of this frame.
   *
   * @param aReflowInput Data structure passed from parent during reflow.
   * @param aReflowStatus A pointer to the reflow status for when we're finished
   *        doing reflow. this will get set appropriately if the block-size
   *        causes us to exceed the current available (page) block-size.
   * @param aContentBSize The block-size of content, precomputed outside of this
   *        function. The final block-size that is used in aMetrics will be set
   *        to either this or the available block-size, whichever is larger, in
   *        the case where our available block-size is constrained, and we
   *        overflow that available block-size.
   * @param aBorderPadding The margins representing the border padding for block
   *        frames. Can be 0.
   * @param aFinalSize Out parameter for final block-size.
   * @param aConsumed The block-size already consumed by our previous-in-flows.
   */
  void ComputeFinalBSize(const ReflowInput& aReflowInput,
                         nsReflowStatus* aStatus,
                         nscoord aContentBSize,
                         const mozilla::LogicalMargin& aBorderPadding,
                         mozilla::LogicalSize& aFinalSize,
                         nscoord aConsumed);

  void Reflow(nsPresContext* aPresContext,
              ReflowOutput& aDesiredSize,
              const ReflowInput& aReflowInput,
              nsReflowStatus& aStatus) override;

  nsresult AttributeChanged(int32_t aNameSpaceID,
                            nsAtom* aAttribute,
                            int32_t aModType) override;

  /**
   * Move any frames on our overflow list to the end of our principal list.
   * @return true if there were any overflow frames
   */
  bool DrainSelfOverflowList() override;

  nsresult StealFrame(nsIFrame* aChild) override;

  void DeleteNextInFlowChild(nsIFrame* aNextInFlow,
                             bool aDeletingEmptyFrames) override;

  /**
    * This is a special method that allows a child class of nsBlockFrame to
    * return a special, customized nsStyleText object to the nsLineLayout
    * constructor. It is used when the nsBlockFrame child needs to specify its
    * custom rendering style.
    */
  virtual const nsStyleText* StyleTextForLineLayout();

  /**
   * Determines whether the collapsed margin carried out of the last
   * line includes the margin-top of a line with clearance (in which
   * case we must avoid collapsing that margin with our bottom margin)
   */
  bool CheckForCollapsedBEndMarginFromClearanceLine();

  static nsresult GetCurrentLine(BlockReflowInput *aState, nsLineBox **aOutCurrentLine);

  /**
   * Determine if this block is a margin root at the top/bottom edges.
   */
  void IsMarginRoot(bool* aBStartMarginRoot, bool* aBEndMarginRoot);

  static bool BlockNeedsFloatManager(nsIFrame* aBlock);

  /**
   * Returns whether aFrame is a block frame that will wrap its contents
   * around floats intruding on it from the outside.  (aFrame need not
   * be a block frame, but if it's not, the result will be false.)
   */
  static bool BlockCanIntersectFloats(nsIFrame* aFrame);

  /**
   * Returns the inline size that needs to be cleared past floats for
   * blocks that cannot intersect floats.  aState must already have
   * GetAvailableSpace called on it for the block-dir position that we
   * care about (which need not be its current mBCoord)
   */
  struct ReplacedElementISizeToClear {
    // Note that we care about the inline-start margin but can ignore
    // the inline-end margin.
    nscoord marginIStart, borderBoxISize;
  };
  static ReplacedElementISizeToClear
    ISizeToClearPastFloats(const BlockReflowInput& aState,
                           const mozilla::LogicalRect& aFloatAvailableSpace,
                           nsIFrame* aFrame);

  /**
   * Creates a contination for aFloat and adds it to the list of overflow floats.
   * Also updates aState.mReflowStatus to include the float's incompleteness.
   * Must only be called while this block frame is in reflow.
   * aFloatStatus must be the float's true, unmodified reflow status.
   */
  void SplitFloat(BlockReflowInput& aState,
                  nsIFrame* aFloat,
                  const nsReflowStatus& aFloatStatus);

  /**
   * Walks up the frame tree, starting with aCandidate, and returns the first
   * block frame that it encounters.
   */
  static nsBlockFrame* GetNearestAncestorBlock(nsIFrame* aCandidate);

  struct FrameLines {
    nsLineList mLines;
    nsFrameList mFrames;
  };

  /**
   * Update the styles of our various pseudo-elements (bullets, first-line,
   * etc, but _not_ first-letter).
   */
  void UpdatePseudoElementStyles(mozilla::ServoRestyleState& aRestyleState);

  // Update our first-letter styles during stylo post-traversal.  This needs to
  // be done at a slightly different time than our other pseudo-elements.
  void UpdateFirstLetterStyle(mozilla::ServoRestyleState& aRestyleState);

protected:
  explicit nsBlockFrame(ComputedStyle* aStyle, ClassID aID = kClassID)
    : nsContainerFrame(aStyle, aID)
    , mMinWidth(NS_INTRINSIC_WIDTH_UNKNOWN)
    , mPrefWidth(NS_INTRINSIC_WIDTH_UNKNOWN)
  {
#ifdef DEBUG
  InitDebugFlags();
#endif
  }

  virtual ~nsBlockFrame();

#ifdef DEBUG
  already_AddRefed<ComputedStyle> GetFirstLetterStyle(nsPresContext* aPresContext);
#endif

  NS_DECLARE_FRAME_PROPERTY_WITHOUT_DTOR(LineCursorProperty, nsLineBox)
  bool HasLineCursor() { return GetStateBits() & NS_BLOCK_HAS_LINE_CURSOR; }
  nsLineBox* GetLineCursor() {
    return HasLineCursor() ? GetProperty(LineCursorProperty()) : nullptr;
  }

  nsLineBox* NewLineBox(nsIFrame* aFrame, bool aIsBlock) {
    return NS_NewLineBox(PresShell(), aFrame, aIsBlock);
  }
  nsLineBox* NewLineBox(nsLineBox* aFromLine, nsIFrame* aFrame, int32_t aCount) {
    return NS_NewLineBox(PresShell(), aFromLine, aFrame, aCount);
  }
  void FreeLineBox(nsLineBox* aLine) {
    if (aLine == GetLineCursor()) {
      ClearLineCursor();
    }
    aLine->Destroy(PresShell());
  }
  /**
   * Helper method for StealFrame.
   */
  void RemoveFrameFromLine(nsIFrame* aChild, nsLineList::iterator aLine,
                           nsFrameList& aFrameList, nsLineList& aLineList);

  void TryAllLines(nsLineList::iterator* aIterator,
                   nsLineList::iterator* aStartIterator,
                   nsLineList::iterator* aEndIterator,
                   bool* aInOverflowLines,
                   FrameLines** aOverflowLines);

  /** move the frames contained by aLine by aDeltaBCoord
    * if aLine is a block, its child floats are added to the state manager
    */
  void SlideLine(BlockReflowInput& aState,
                 nsLineBox* aLine, nscoord aDeltaBCoord);

  void UpdateLineContainerSize(nsLineBox* aLine,
                               const nsSize& aNewContainerSize);

  // helper for SlideLine and UpdateLineContainerSize
  void MoveChildFramesOfLine(nsLineBox* aLine, nscoord aDeltaBCoord);

  void ComputeFinalSize(const ReflowInput& aReflowInput,
                        BlockReflowInput& aState,
                        ReflowOutput& aMetrics,
                        nscoord* aBottomEdgeOfChildren);

  void ComputeOverflowAreas(const nsRect& aBounds,
                            const nsStyleDisplay* aDisplay,
                            nscoord aBottomEdgeOfChildren,
                            nsOverflowAreas& aOverflowAreas);

  /**
   * Add the frames in aFrameList to this block after aPrevSibling.
   * This block thinks in terms of lines, but the frame construction code
   * knows nothing about lines at all so we need to find the line that
   * contains aPrevSibling and add aFrameList after aPrevSibling on that line.
   * New lines are created as necessary to handle block data in aFrameList.
   * This function will clear aFrameList.
   */
  void AddFrames(nsFrameList& aFrameList, nsIFrame* aPrevSibling);

  /**
   * Perform Bidi resolution on this frame
   */
  nsresult ResolveBidi();

  /**
   * Test whether the frame is a form control in a visual Bidi page.
   * This is necessary for backwards-compatibility, because most visual
   * pages use logical order for form controls so that they will
   * display correctly on native widgets in OSs with Bidi support
   * @param aPresContext the pres context
   * @return whether the frame is a BIDI form control
   */
  bool IsVisualFormControl(nsPresContext* aPresContext);

public:
  /**
   * Helper function to create bullet frame.
   */
  void CreateBulletFrameForListItem();

  /**
   * Does all the real work for removing aDeletedFrame
   * -- finds the line containing aDeletedFrame
   * -- removes all aDeletedFrame next-in-flows (or all continuations,
   * if REMOVE_FIXED_CONTINUATIONS is given)
   * -- marks lines dirty as needed
   * -- marks textruns dirty (unless FRAMES_ARE_EMPTY is given, in which
   * case textruns do not need to be dirtied)
   * -- destroys all removed frames
   */
  enum {
    REMOVE_FIXED_CONTINUATIONS = 0x02,
    FRAMES_ARE_EMPTY = 0x04
  };
  void DoRemoveFrame(nsIFrame* aDeletedFrame, uint32_t aFlags)
  {
    AutoPostDestroyData data(PresContext());
    DoRemoveFrameInternal(aDeletedFrame, aFlags, data.mData);
  }

  void ReparentFloats(nsIFrame* aFirstFrame, nsBlockFrame* aOldParent,
                      bool aReparentSiblings, ReparentingDirection aDirection);

  virtual bool ComputeCustomOverflow(nsOverflowAreas& aOverflowAreas) override;

  virtual void UnionChildOverflow(nsOverflowAreas& aOverflowAreas) override;

  /** Load all of aFrame's floats into the float manager iff aFrame is not a
   *  block formatting context. Handles all necessary float manager translations;
   *  assumes float manager is in aFrame's parent's coord system.
   *  Safe to call on non-blocks (does nothing).
   */
  static void RecoverFloatsFor(nsIFrame* aFrame,
                               nsFloatManager& aFloatManager,
                               mozilla::WritingMode aWM,
                               const nsSize& aContainerSize);

  /**
   * Determine if we have any pushed floats from a previous continuation.
   *
   * @returns true, if any of the floats at the beginning of our mFloats list
   *          have the NS_FRAME_IS_PUSHED_FLOAT bit set; false otherwise.
   */
  bool HasPushedFloatsFromPrevContinuation() const {
    if (!mFloats.IsEmpty()) {
      // If we have pushed floats, then they should be at the beginning of our
      // float list.
      if (mFloats.FirstChild()->GetStateBits() & NS_FRAME_IS_PUSHED_FLOAT) {
        return true;
      }
    }

#ifdef DEBUG
    // Double-check the above assertion that pushed floats should be at the
    // beginning of our floats list.
    for (nsFrameList::Enumerator e(mFloats); !e.AtEnd(); e.Next()) {
      nsIFrame* f = e.get();
      NS_ASSERTION(!(f->GetStateBits() & NS_FRAME_IS_PUSHED_FLOAT),
        "pushed floats must be at the beginning of the float list");
    }
#endif

    // We may have a pending push of pushed floats too:
    if (HasPushedFloats()) {
      // XXX we can return 'true' here once we make HasPushedFloats
      // not lie.  (see nsBlockFrame::RemoveFloat)
      auto* pushedFloats = GetPushedFloats();
      return pushedFloats && !pushedFloats->IsEmpty();
    }
    return false;
  }

  virtual bool RenumberChildFrames(int32_t* aOrdinal,
                                   int32_t aDepth,
                                   int32_t aIncrement,
                                   bool aForCounting) override;

  // @see nsIFrame::AddSizeOfExcludingThisForTree
  void AddSizeOfExcludingThisForTree(nsWindowSizes&) const override;

protected:
  /** @see DoRemoveFrame */
  void DoRemoveFrameInternal(nsIFrame* aDeletedFrame, uint32_t aFlags,
                             PostDestroyData& data);

  /** grab overflow lines from this block's prevInFlow, and make them
    * part of this block's mLines list.
    * @return true if any lines were drained.
    */
  bool DrainOverflowLines();

  /**
   * @return false iff this block does not have a float on any child list.
   * This function is O(1).
   */
  bool MaybeHasFloats() const {
    if (!mFloats.IsEmpty()) {
      return true;
    }
    // XXX this could be replaced with HasPushedFloats() if we enforced
    // removing the property when the frame list becomes empty.
    nsFrameList* list = GetPushedFloats();
    if (list && !list->IsEmpty()) {
      return true;
    }
    // For the OverflowOutOfFlowsProperty I think we do enforce that, but it's
    // a mix of out-of-flow frames, so that's why the method name has "Maybe".
    return GetStateBits() & NS_BLOCK_HAS_OVERFLOW_OUT_OF_FLOWS;
  }

  /**
   * Moves frames from our PushedFloats list back into our mFloats list.
   */
  void DrainSelfPushedFloats();

  /**
   * First calls DrainSelfPushedFloats() then grabs pushed floats from this
   * block's prev-in-flow, and splice them into this block's mFloats list too.
   */
  void DrainPushedFloats();

  /** Load all our floats into the float manager (without reflowing them).
   *  Assumes float manager is in our own coordinate system.
   */
  void RecoverFloats(nsFloatManager& aFloatManager,
                     mozilla::WritingMode aWM,
                     const nsSize& aContainerSize);

  /** Reflow pushed floats
   */
  void ReflowPushedFloats(BlockReflowInput& aState,
                          nsOverflowAreas& aOverflowAreas,
                          nsReflowStatus& aStatus);

  /** Find any trailing BR clear from the last line of the block (or its PIFs)
   */
  mozilla::StyleClear FindTrailingClear();

  /**
   * Remove a float from our float list.
   */
  void RemoveFloat(nsIFrame* aFloat);
  /**
   * Remove a float from the float cache for the line its placeholder is on.
   */
  void RemoveFloatFromFloatCache(nsIFrame* aFloat);

  void CollectFloats(nsIFrame* aFrame, nsFrameList& aList,
                     bool aCollectFromSiblings) {
    if (MaybeHasFloats()) {
      DoCollectFloats(aFrame, aList, aCollectFromSiblings);
    }
  }
  void DoCollectFloats(nsIFrame* aFrame, nsFrameList& aList,
                       bool aCollectFromSiblings);

  // Remove a float, abs, rel positioned frame from the appropriate block's list
  static void DoRemoveOutOfFlowFrame(nsIFrame* aFrame);

  /** set up the conditions necessary for an resize reflow
    * the primary task is to mark the minimumly sufficient lines dirty.
    */
  void PrepareResizeReflow(BlockReflowInput& aState);

  /** reflow all lines that have been marked dirty */
  void ReflowDirtyLines(BlockReflowInput& aState);

  /** Mark a given line dirty due to reflow being interrupted on or before it */
  void MarkLineDirtyForInterrupt(nsLineBox* aLine);

  //----------------------------------------
  // Methods for line reflow
  /**
   * Reflow a line.
   * @param aState           the current reflow state
   * @param aLine            the line to reflow.  can contain a single block frame
   *                         or contain 1 or more inline frames.
   * @param aKeepReflowGoing [OUT] indicates whether the caller should continue to reflow more lines
   */
  void ReflowLine(BlockReflowInput& aState,
                  LineIterator aLine,
                  bool* aKeepReflowGoing);

  // Return false if it needs another reflow because of reduced space
  // between floats that are next to it (but not next to its top), and
  // return true otherwise.
  bool PlaceLine(BlockReflowInput& aState,
                 nsLineLayout& aLineLayout,
                 LineIterator aLine,
                 nsFloatManager::SavedState* aFloatStateBeforeLine,
                 nsFlowAreaRect& aFlowArea, // in-out
                 nscoord& aAvailableSpaceBSize, // in-out
                 bool* aKeepReflowGoing);

  /**
    * If NS_BLOCK_LOOK_FOR_DIRTY_FRAMES is set, call MarkLineDirty
    * on any line with a child frame that is dirty.
    */
  void LazyMarkLinesDirty();

  /**
   * Mark |aLine| dirty, and, if necessary because of possible
   * pull-up, mark the previous line dirty as well. Also invalidates textruns
   * on those lines because the text in the lines might have changed due to
   * addition/removal of frames.
   * @param aLine the line to mark dirty
   * @param aLineList the line list containing that line
   */
  void MarkLineDirty(LineIterator aLine, const nsLineList* aLineList);

  // XXX where to go
  bool IsLastLine(BlockReflowInput& aState,
                  LineIterator aLine);

  void DeleteLine(BlockReflowInput& aState,
                  nsLineList::iterator aLine,
                  nsLineList::iterator aLineEnd);

  //----------------------------------------
  // Methods for individual frame reflow

  bool ShouldApplyBStartMargin(BlockReflowInput& aState,
                               nsLineBox* aLine,
                               nsIFrame* aChildFrame);

  void ReflowBlockFrame(BlockReflowInput& aState,
                        LineIterator aLine,
                        bool* aKeepGoing);

  void ReflowInlineFrames(BlockReflowInput& aState,
                          LineIterator aLine,
                          bool* aKeepLineGoing);

  void DoReflowInlineFrames(BlockReflowInput& aState,
                            nsLineLayout& aLineLayout,
                            LineIterator aLine,
                            nsFlowAreaRect& aFloatAvailableSpace,
                            nscoord& aAvailableSpaceBSize,
                            nsFloatManager::SavedState* aFloatStateBeforeLine,
                            bool* aKeepReflowGoing,
                            LineReflowStatus* aLineReflowStatus,
                            bool aAllowPullUp);

  void ReflowInlineFrame(BlockReflowInput& aState,
                         nsLineLayout& aLineLayout,
                         LineIterator aLine,
                         nsIFrame* aFrame,
                         LineReflowStatus* aLineReflowStatus);

  // Compute the available inline size for a float.
  mozilla::LogicalRect AdjustFloatAvailableSpace(
                         BlockReflowInput& aState,
                         const mozilla::LogicalRect& aFloatAvailableSpace,
                         nsIFrame* aFloatFrame);
  // Computes the border-box inline size of the float
  nscoord ComputeFloatISize(BlockReflowInput& aState,
                            const mozilla::LogicalRect& aFloatAvailableSpace,
                            nsIFrame* aFloat);
  // An incomplete aReflowStatus indicates the float should be split
  // but only if the available height is constrained.
  // aAdjustedAvailableSpace is the result of calling
  // nsBlockFrame::AdjustFloatAvailableSpace.
  void ReflowFloat(BlockReflowInput& aState,
                   const mozilla::LogicalRect& aAdjustedAvailableSpace,
                   nsIFrame* aFloat,
                   mozilla::LogicalMargin& aFloatMargin,
                   mozilla::LogicalMargin& aFloatOffsets,
                   // Whether the float's position
                   // (aAdjustedAvailableSpace) has been pushed down
                   // due to the presence of other floats.
                   bool aFloatPushedDown,
                   nsReflowStatus& aReflowStatus);

  //----------------------------------------
  // Methods for pushing/pulling lines/frames

  /**
   * Create a next-in-flow, if necessary, for aFrame. If a new frame is
   * created, place it in aLine if aLine is not null.
   * @param aState the block reflow state
   * @param aLine where to put a new frame
   * @param aFrame the frame
   * @return true if a new frame was created, false if not
   */
  bool CreateContinuationFor(BlockReflowInput& aState,
                             nsLineBox* aLine,
                             nsIFrame* aFrame);

  /**
   * Push aLine (and any after it), since it cannot be placed on this
   * page/column.  Set aKeepReflowGoing to false and set
   * flag aState.mReflowStatus as incomplete.
   */
  void PushTruncatedLine(BlockReflowInput& aState,
                         LineIterator aLine,
                         bool* aKeepReflowGoing);

  void SplitLine(BlockReflowInput& aState,
                 nsLineLayout& aLineLayout,
                 LineIterator aLine,
                 nsIFrame* aFrame,
                 LineReflowStatus* aLineReflowStatus);

  /**
   * Pull a frame from the next available location (one of our lines or
   * one of our next-in-flows lines).
   * @return the pulled frame or nullptr
   */
  nsIFrame* PullFrame(BlockReflowInput& aState,
                      LineIterator aLine);

  /**
   * Try to pull a frame out of a line pointed at by aFromLine.
   *
   * Note: pulling a frame from a line that is a place-holder frame
   * doesn't automatically remove the corresponding float from the
   * line's float array. This happens indirectly: either the line gets
   * emptied (and destroyed) or the line gets reflowed (because we mark
   * it dirty) and the code at the top of ReflowLine empties the
   * array. So eventually, it will be removed, just not right away.
   *
   * @return the pulled frame or nullptr
   */
  nsIFrame* PullFrameFrom(nsLineBox* aLine,
                          nsBlockFrame* aFromContainer,
                          nsLineList::iterator aFromLine);

  /**
   * Push the line after aLineBefore to the overflow line list.
   * @param aLineBefore a line in 'mLines' (or LinesBegin() when
   *        pushing the first line)
   */
  void PushLines(BlockReflowInput& aState,
                 nsLineList::iterator aLineBefore);

  void PropagateFloatDamage(BlockReflowInput& aState,
                            nsLineBox* aLine,
                            nscoord aDeltaBCoord);

  void CheckFloats(BlockReflowInput& aState);

  //----------------------------------------
  // List handling kludge

  void ReflowBullet(nsIFrame* aBulletFrame,
                    BlockReflowInput& aState,
                    ReflowOutput& aMetrics,
                    nscoord aLineTop);

  //----------------------------------------

  virtual nsILineIterator* GetLineIterator() override;

public:
  bool HasOverflowLines() const {
    return 0 != (GetStateBits() & NS_BLOCK_HAS_OVERFLOW_LINES);
  }
  FrameLines* GetOverflowLines() const;
protected:
  FrameLines* RemoveOverflowLines();
  void SetOverflowLines(FrameLines* aOverflowLines);
  void DestroyOverflowLines();

  /**
   * This class is useful for efficiently modifying the out of flow
   * overflow list. It gives the client direct writable access to
   * the frame list temporarily but ensures that property is only
   * written back if absolutely necessary.
   */
  struct nsAutoOOFFrameList {
    nsFrameList mList;

    explicit nsAutoOOFFrameList(nsBlockFrame* aBlock)
      : mPropValue(aBlock->GetOverflowOutOfFlows())
      , mBlock(aBlock) {
      if (mPropValue) {
        mList = *mPropValue;
      }
    }
    ~nsAutoOOFFrameList() {
      mBlock->SetOverflowOutOfFlows(mList, mPropValue);
    }
  protected:
    nsFrameList* const mPropValue;
    nsBlockFrame* const mBlock;
  };
  friend struct nsAutoOOFFrameList;

  nsFrameList* GetOverflowOutOfFlows() const;
  void SetOverflowOutOfFlows(const nsFrameList& aList, nsFrameList* aPropValue);

  /**
   * @return the inside bullet frame or nullptr if we don't have one.
   */
  nsBulletFrame* GetInsideBullet() const;

  /**
   * @return the outside bullet frame or nullptr if we don't have one.
   */
  nsBulletFrame* GetOutsideBullet() const;

  /**
   * @return the outside bullet frame list frame property.
   */
  nsFrameList* GetOutsideBulletList() const;

  /**
   * @return true if this frame has pushed floats.
   */
  bool HasPushedFloats() const {
    return 0 != (GetStateBits() & NS_BLOCK_HAS_PUSHED_FLOATS);
  }

  // Get the pushed floats list, which is used for *temporary* storage
  // of floats during reflow, between when we decide they don't fit in
  // this block until our next continuation takes them.
  nsFrameList* GetPushedFloats() const;
  // Get the pushed floats list, or if there is not currently one,
  // make a new empty one.
  nsFrameList* EnsurePushedFloats();
  // Remove and return the pushed floats list.
  nsFrameList* RemovePushedFloats();

  // Resolve a ComputedStyle for our bullet frame.  aType should be
  // mozListBullet or mozListNumber.  Passing in the style set is an
  // optimization, because all callsites have it.
  already_AddRefed<ComputedStyle> ResolveBulletStyle(
    mozilla::CSSPseudoElementType aType,
    mozilla::ServoStyleSet* aStyleSet);

#ifdef DEBUG
  void VerifyLines(bool aFinalCheckOK);
  void VerifyOverflowSituation();
  int32_t GetDepth() const;
#endif

  // FIXME The two variables should go through a renaming refactoring to reflect
  // the fact that they mean an inline size, not a width.
  nscoord mMinWidth, mPrefWidth;

  nsLineList mLines;

  // List of all floats in this block
  // XXXmats blocks rarely have floats, make it a frame property
  nsFrameList mFloats;

  friend class mozilla::BlockReflowInput;
  friend class nsBlockInFlowLineIterator;

#ifdef DEBUG
public:
  static bool gLamePaintMetrics;
  static bool gLameReflowMetrics;
  static bool gNoisy;
  static bool gNoisyDamageRepair;
  static bool gNoisyIntrinsic;
  static bool gNoisyReflow;
  static bool gReallyNoisyReflow;
  static bool gNoisyFloatManager;
  static bool gVerifyLines;
  static bool gDisableResizeOpt;

  static int32_t gNoiseIndent;

  static const char* kReflowCommandType[];

protected:
  static void InitDebugFlags();
#endif
};

#ifdef DEBUG
class AutoNoisyIndenter {
public:
  explicit AutoNoisyIndenter(bool aDoIndent) : mIndented(aDoIndent) {
    if (mIndented) {
      nsBlockFrame::gNoiseIndent++;
    }
  }
  ~AutoNoisyIndenter() {
    if (mIndented) {
      nsBlockFrame::gNoiseIndent--;
    }
  }
private:
  bool mIndented;
};
#endif

/**
 * Iterates over all lines in the prev-in-flows/next-in-flows of this block.
 */
class nsBlockInFlowLineIterator {
public:
  typedef nsBlockFrame::LineIterator LineIterator;
  /**
   * Set up the iterator to point to aLine which must be a normal line
   * in aFrame (not an overflow line).
   */
  nsBlockInFlowLineIterator(nsBlockFrame* aFrame, LineIterator aLine);
  /**
   * Set up the iterator to point to the first line found starting from
   * aFrame. Sets aFoundValidLine to false if there is no such line.
   * After aFoundValidLine has returned false, don't call any methods on this
   * object again.
   */
  nsBlockInFlowLineIterator(nsBlockFrame* aFrame, bool* aFoundValidLine);
  /**
   * Set up the iterator to point to the line that contains aFindFrame (either
   * directly or indirectly).  If aFrame is out of flow, or contained in an
   * out-of-flow, finds the line containing the out-of-flow's placeholder. If
   * the frame is not found, sets aFoundValidLine to false. After
   * aFoundValidLine has returned false, don't call any methods on this
   * object again.
   */
  nsBlockInFlowLineIterator(nsBlockFrame* aFrame, nsIFrame* aFindFrame,
                            bool* aFoundValidLine);

  LineIterator GetLine() { return mLine; }
  bool IsLastLineInList();
  nsBlockFrame* GetContainer() { return mFrame; }
  bool GetInOverflow() { return mLineList != &mFrame->mLines; }

  /**
   * Returns the current line list we're iterating, null means
   * we're iterating |mLines| of the container.
   */
  nsLineList* GetLineList() { return mLineList; }

  /**
   * Returns the end-iterator of whatever line list we're in.
   */
  LineIterator End();

  /**
   * Returns false if there are no more lines. After this has returned false,
   * don't call any methods on this object again.
   */
  bool Next();
  /**
   * Returns false if there are no more lines. After this has returned false,
   * don't call any methods on this object again.
   */
  bool Prev();

private:
  friend class nsBlockFrame;
  friend class nsBidiPresUtils;
  // XXX nsBlockFrame uses this internally in one place.  Try to remove it.
  // XXX uhm, and nsBidiPresUtils::Resolve too.
  nsBlockInFlowLineIterator(nsBlockFrame* aFrame, LineIterator aLine, bool aInOverflow);

  nsBlockFrame* mFrame;
  LineIterator mLine;
  nsLineList* mLineList;  // the line list mLine is in

  /**
   * Moves iterator to next valid line reachable from the current block.
   * Returns false if there are no valid lines.
   */
  bool FindValidLine();
};

#endif /* nsBlockFrame_h___ */