layout/generic/nsFlexContainerFrame.h
author Nika Layzell <nika@thelayzells.com>
Tue, 25 Sep 2018 17:34:53 +0200
changeset 507828 5e6dae0c1e5a4939ccd406f14607f7fafffd45a7
parent 506105 04f110532f4974387e48a3272fe219188299b205
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: flex" and "display: -webkit-box" */

#ifndef nsFlexContainerFrame_h___
#define nsFlexContainerFrame_h___

#include "nsContainerFrame.h"
#include "mozilla/UniquePtr.h"
#include "mozilla/dom/FlexBinding.h"

class nsStyleCoord;

namespace mozilla {
template <class T> class LinkedList;
class LogicalPoint;
} // namespace mozilla

nsContainerFrame* NS_NewFlexContainerFrame(nsIPresShell* aPresShell,
                                           mozilla::ComputedStyle* aStyle);

/**
 * These structures are used to capture data during reflow to be
 * extracted by devtools via Chrome APIs. The structures are only
 * created when requested in GetFlexFrameWithComputedInfo(), and
 * the structures are attached to the nsFlexContainerFrame via the
 * FlexContainerInfo property.
 */
struct ComputedFlexItemInfo
{
  nsCOMPtr<nsINode> mNode;
  nsRect mFrameRect;
  /**
   * mMainBaseSize is a measure of the size of the item in the main
   * axis before the flex sizing algorithm is applied. In the spec,
   * this is called "flex base size", but we use this name to connect
   * the value to the other main axis sizes.
   */
  nscoord mMainBaseSize;
  /**
   * mMainDeltaSize is the amount that the flex sizing algorithm
   * adds to the mMainBaseSize, before clamping to mMainMinSize and
   * mMainMaxSize. This can be thought of as the amount by which the
   * flex layout algorithm "wants" to shrink or grow the item, and
   * would do, if it was unconstrained. Since the flex sizing
   * algorithm proceeds linearly, the mMainDeltaSize for an item only
   * respects the resolved size of items already frozen.
   */
  nscoord mMainDeltaSize;
  nscoord mMainMinSize;
  nscoord mMainMaxSize;
  nscoord mCrossMinSize;
  nscoord mCrossMaxSize;
  mozilla::dom::FlexItemClampState mClampState;
};

struct ComputedFlexLineInfo
{
  nsTArray<ComputedFlexItemInfo> mItems;
  nscoord mCrossStart;
  nscoord mCrossSize;
  nscoord mFirstBaselineOffset;
  nscoord mLastBaselineOffset;
  mozilla::dom::FlexLineGrowthState mGrowthState;
};

struct ComputedFlexContainerInfo
{
  nsTArray<ComputedFlexLineInfo> mLines;
  mozilla::dom::FlexPhysicalDirection mMainAxisDirection;
  mozilla::dom::FlexPhysicalDirection mCrossAxisDirection;
};

/**
 * This is the rendering object used for laying out elements with
 * "display: flex" or "display: inline-flex".
 *
 * We also use this class for elements with "display: -webkit-box" or
 * "display: -webkit-inline-box" (but not "-moz-box" / "-moz-inline-box" --
 * those are rendered with old-school XUL frame classes).
 *
 * Note: we represent the -webkit-box family of properties (-webkit-box-orient,
 * -webkit-box-flex, etc.) as aliases for their -moz equivalents.  And for
 * -webkit-{inline-}box containers, nsFlexContainerFrame will honor those
 * "legacy" properties for alignment/flexibility/etc. *instead of* honoring the
 * modern flexbox & alignment properties.  For brevity, many comments in
 * nsFlexContainerFrame.cpp simply refer to these properties using their
 * "-webkit" versions, since we're mostly expecting to encounter them in that
 * form. (Technically, the "-moz" versions of these properties *can* influence
 * layout here as well (since that's what the -webkit versions are aliased to)
 * -- but only inside of a "display:-webkit-{inline-}box" container.)
 */
class nsFlexContainerFrame final : public nsContainerFrame
{
public:
  NS_DECL_FRAMEARENA_HELPERS(nsFlexContainerFrame)
  NS_DECL_QUERYFRAME

  // Factory method:
  friend nsContainerFrame* NS_NewFlexContainerFrame(nsIPresShell* aPresShell,
                                                    ComputedStyle* aStyle);

  // Forward-decls of helper classes
  class FlexItem;
  class FlexLine;
  class FlexboxAxisTracker;
  struct StrutInfo;
  class CachedMeasuringReflowResult;

  // nsIFrame overrides
  void Init(nsIContent*       aContent,
            nsContainerFrame* aParent,
            nsIFrame*         aPrevInFlow) override;

  void BuildDisplayList(nsDisplayListBuilder*   aBuilder,
                        const nsDisplayListSet& aLists) override;

  void MarkIntrinsicISizesDirty() override;

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

  void DidReflow(nsPresContext*, const ReflowInput*) final;

  nscoord GetMinISize(gfxContext* aRenderingContext) override;
  nscoord GetPrefISize(gfxContext* aRenderingContext) override;

#ifdef DEBUG_FRAME_DUMP
  nsresult GetFrameName(nsAString& aResult) const override;
#endif

  nscoord GetLogicalBaseline(mozilla::WritingMode aWM) const override;

  bool GetVerticalAlignBaseline(mozilla::WritingMode aWM,
                                nscoord* aBaseline) const override
  {
    return GetNaturalBaselineBOffset(aWM, BaselineSharingGroup::eFirst, aBaseline);
  }

  bool GetNaturalBaselineBOffset(mozilla::WritingMode aWM,
                                 BaselineSharingGroup aBaselineGroup,
                                 nscoord*             aBaseline) const override
  {
    if (HasAnyStateBits(NS_STATE_FLEX_SYNTHESIZE_BASELINE)) {
      return false;
    }
    *aBaseline = aBaselineGroup == BaselineSharingGroup::eFirst ?
                   mBaselineFromLastReflow : mLastBaselineFromLastReflow;
    return true;
  }

  // nsContainerFrame overrides
  uint16_t CSSAlignmentForAbsPosChild(
            const ReflowInput& aChildRI,
            mozilla::LogicalAxis aLogicalAxis) const override;

  /**
   * Helper function to calculate packing space and initial offset of alignment
   * subjects in MainAxisPositionTracker() and CrossAxisPositionTracker() for
   * space-between, space-around, and space-evenly.
   *    * @param aNumThingsToPack             Number of alignment subjects.
   * @param aAlignVal                    Value for align-self or justify-self.
   * @param aFirstSubjectOffset          Outparam for first subject offset.
   * @param aNumPackingSpacesRemaining   Outparam for number of equal-sized
   *                                     packing spaces to apply between each
   *                                     alignment subject.
   * @param aPackingSpaceRemaining       Outparam for total amount of packing
   *                                     space to be divided up.
   */
  static void CalculatePackingSpace(uint32_t aNumThingsToPack,
                                    uint8_t aAlignVal,
                                    nscoord* aFirstSubjectOffset,
                                    uint32_t* aNumPackingSpacesRemaining,
                                    nscoord* aPackingSpaceRemaining);

  /**
   * This property is created by a call to
   * nsFlexContainerFrame::GetFlexFrameWithComputedInfo.
   */
  NS_DECLARE_FRAME_PROPERTY_DELETABLE(FlexContainerInfo, ComputedFlexContainerInfo)
  /**
   * This function should only be called on a nsFlexContainerFrame
   * that has just been returned by a call to
   * GetFlexFrameWithComputedInfo.
   */
  const ComputedFlexContainerInfo* GetFlexContainerInfo()
  {
    const ComputedFlexContainerInfo* info = GetProperty(FlexContainerInfo());
    MOZ_ASSERT(info, "Property generation wasn't requested.");
    return info;
  }

  /**
   * Return aFrame as a flex frame after ensuring it has computed flex info.
   * @return nullptr if aFrame is null or doesn't have a flex frame
   *         as its content insertion frame.
   * @note this might destroy layout/style data since it may flush layout.
   */
  static nsFlexContainerFrame* GetFlexFrameWithComputedInfo(nsIFrame* aFrame);

  /**
   * Given a frame for a flex item, this method returns true IFF that flex
   * item's inline axis is the same as (i.e. not orthogonal to) its flex
   * container's main axis.
   *
   * (This method is only intended to be used from external
   * callers. Inside of flex reflow code, FlexItem::IsInlineAxisMainAxis() is
   * equivalent & more optimal.)
   *
   * @param aFrame a flex item (must return true from IsFlexItem)
   * @return true iff aFrame's inline axis is the same as (i.e. not orthogonal
   *              to) its flex container's main axis. Otherwise, false.
   */
  static bool IsItemInlineAxisMainAxis(nsIFrame* aFrame);

  /**
   * Returns true iff the given computed 'flex-basis' & main-size property
   * values collectively represent a used flex-basis of 'content'.
   * See https://drafts.csswg.org/css-flexbox-1/#valdef-flex-basis-auto
   *
   * @param aFlexBasis the computed 'flex-basis' for a flex item.
   * @param aMainSize the computed main-size property for a flex item.
   */
  static bool IsUsedFlexBasisContent(const nsStyleCoord* aFlexBasis,
                                     const nsStyleCoord* aMainSize);

  /**
   * Callback for nsFrame::MarkIntrinsicISizesDirty() on a flex item.
   */
  static void MarkCachedFlexMeasurementsDirty(nsIFrame* aItemFrame);

protected:
  // Protected constructor & destructor
  explicit nsFlexContainerFrame(ComputedStyle* aStyle)
    : nsContainerFrame(aStyle, kClassID)
    , mCachedMinISize(NS_INTRINSIC_WIDTH_UNKNOWN)
    , mCachedPrefISize(NS_INTRINSIC_WIDTH_UNKNOWN)
    , mBaselineFromLastReflow(NS_INTRINSIC_WIDTH_UNKNOWN)
    , mLastBaselineFromLastReflow(NS_INTRINSIC_WIDTH_UNKNOWN)
  {}

  virtual ~nsFlexContainerFrame();

  /*
   * This method does the bulk of the flex layout, implementing the algorithm
   * described at:
   *   http://dev.w3.org/csswg/css-flexbox/#layout-algorithm
   * (with a few initialization pieces happening in the caller, Reflow().
   *
   * Since this is a helper for Reflow(), this takes all the same parameters
   * as Reflow(), plus a few more parameters that Reflow() sets up for us.
   *
   * (The logic behind the division of work between Reflow and DoFlexLayout is
   * as follows: DoFlexLayout() begins at the step that we have to jump back
   * to, if we find any visibility:collapse children, and Reflow() does
   * everything before that point.)
   */
  void DoFlexLayout(nsPresContext*           aPresContext,
                    ReflowOutput&     aDesiredSize,
                    const ReflowInput& aReflowInput,
                    nsReflowStatus&          aStatus,
                    nscoord aContentBoxMainSize,
                    nscoord aAvailableBSizeForContent,
                    nsTArray<StrutInfo>& aStruts,
                    const FlexboxAxisTracker& aAxisTracker,
                    nscoord aMainGapSize,
                    nscoord aCrossGapSize);

  /**
   * Checks whether our child-frame list "mFrames" is sorted, using the given
   * IsLessThanOrEqual function, and sorts it if it's not already sorted.
   *
   * XXXdholbert Once we support pagination, we need to make this function
   * check our continuations as well (or wrap it in a function that does).
   *
   * @return true if we had to sort mFrames, false if it was already sorted.
   */
  template<bool IsLessThanOrEqual(nsIFrame*, nsIFrame*)>
  bool SortChildrenIfNeeded();

  // Protected flex-container-specific methods / member-vars
#ifdef DEBUG
  void SanityCheckAnonymousFlexItems() const;
#endif // DEBUG

  /*
   * Returns a new FlexItem for the given child frame, allocated on the heap.
   * Guaranteed to return non-null. Caller is responsible for managing the
   * FlexItem's lifetime.
   *
   * Before returning, this method also processes the FlexItem to resolve its
   * flex basis (including e.g. auto-height) as well as to resolve
   * "min-height:auto", via ResolveAutoFlexBasisAndMinSize(). (Basically, the
   * returned FlexItem will be ready to participate in the "Resolve the
   * Flexible Lengths" step of the Flex Layout Algorithm.)
   */
  mozilla::UniquePtr<FlexItem> GenerateFlexItemForChild(nsPresContext* aPresContext,
                                     nsIFrame* aChildFrame,
                                     const ReflowInput& aParentReflowInput,
                                     const FlexboxAxisTracker& aAxisTracker);

  /**
   * This method gets a cached measuring reflow for a flex item, or does it and
   * caches it.
   *
   * This avoids exponential reflows, see the comment on
   * CachedMeasuringReflowResult.
   */
  const CachedMeasuringReflowResult& MeasureAscentAndBSizeForFlexItem(
    FlexItem& aItem,
    nsPresContext* aPresContext,
    ReflowInput& aChildReflowInput);

  /**
   * This method performs a "measuring" reflow to get the content BSize of
   * aFlexItem.Frame() (treating it as if it had a computed BSize of "auto"),
   * and returns the resulting BSize measurement.
   * (Helper for ResolveAutoFlexBasisAndMinSize().)
   */
  nscoord MeasureFlexItemContentBSize(nsPresContext* aPresContext,
                                      FlexItem& aFlexItem,
                                      bool aForceBResizeForMeasuringReflow,
                                      const ReflowInput& aParentReflowInput);

  /**
   * This method resolves an "auto" flex-basis and/or min-main-size value
   * on aFlexItem, if needed.
   * (Helper for GenerateFlexItemForChild().)
   */
  void ResolveAutoFlexBasisAndMinSize(nsPresContext* aPresContext,
                                      FlexItem& aFlexItem,
                                      const ReflowInput& aItemReflowInput,
                                      const FlexboxAxisTracker& aAxisTracker);

  /**
   * Returns true if "this" is the nsFlexContainerFrame for a -moz-box or
   * a -moz-inline-box -- these boxes have special behavior for flex items with
   * "visibility:collapse".
   *
   * @param aFlexStyleDisp This frame's StyleDisplay(). (Just an optimization to
   *                       avoid repeated lookup; some callers already have it.)
   * @return true if "this" is the nsFlexContainerFrame for a -moz-{inline}box.
   */
  bool ShouldUseMozBoxCollapseBehavior(const nsStyleDisplay* aFlexStyleDisp);

  /**
   * This method:
   *  - Creates FlexItems for all of our child frames (except placeholders).
   *  - Groups those FlexItems into FlexLines.
   *  - Returns those FlexLines in the outparam |aLines|.
   *
   * For any child frames which are placeholders, this method will instead just
   * append that child to the outparam |aPlaceholders| for separate handling.
   * (Absolutely positioned children of a flex container are *not* flex items.)
   */
  void GenerateFlexLines(nsPresContext* aPresContext,
                         const ReflowInput& aReflowInput,
                         nscoord aContentBoxMainSize,
                         nscoord aAvailableBSizeForContent,
                         const nsTArray<StrutInfo>& aStruts,
                         const FlexboxAxisTracker& aAxisTracker,
                         nscoord aMainGapSize,
                         nsTArray<nsIFrame*>& aPlaceholders,
                         mozilla::LinkedList<FlexLine>& aLines);

  nscoord GetMainSizeFromReflowInput(const ReflowInput& aReflowInput,
                                     const FlexboxAxisTracker& aAxisTracker);

  nscoord ComputeCrossSize(const ReflowInput& aReflowInput,
                           const FlexboxAxisTracker& aAxisTracker,
                           nscoord aSumLineCrossSizes,
                           nscoord aAvailableBSizeForContent,
                           bool* aIsDefinite,
                           nsReflowStatus& aStatus);

  void SizeItemInCrossAxis(nsPresContext* aPresContext,
                           const FlexboxAxisTracker& aAxisTracker,
                           ReflowInput& aChildReflowInput,
                           FlexItem& aItem);

  /**
   * Moves the given flex item's frame to the given LogicalPosition (modulo any
   * relative positioning).
   *
   * This can be used in cases where we've already done a "measuring reflow"
   * for the flex item at the correct size, and hence can skip its final reflow
   * (but still need to move it to the right final position).
   *
   * @param aReflowInput    The flex container's reflow state.
   * @param aItem           The flex item whose frame should be moved.
   * @param aFramePos       The position where the flex item's frame should
   *                        be placed. (pre-relative positioning)
   * @param aContainerSize  The flex container's size (required by some methods
   *                        that we call, to interpret aFramePos correctly).
   */
  void MoveFlexItemToFinalPosition(const ReflowInput& aReflowInput,
                                   const FlexItem& aItem,
                                   mozilla::LogicalPoint& aFramePos,
                                   const nsSize& aContainerSize);
  /**
   * Helper-function to reflow a child frame, at its final position determined
   * by flex layout.
   *
   * @param aPresContext    The presentation context being used in reflow.
   * @param aAxisTracker    A FlexboxAxisTracker with the flex container's axes.
   * @param aReflowInput    The flex container's reflow state.
   * @param aItem           The flex item to be reflowed.
   * @param aFramePos       The position where the flex item's frame should
   *                        be placed. (pre-relative positioning)
   * @param aContainerSize  The flex container's size (required by some methods
   *                        that we call, to interpret aFramePos correctly).
   */
  void ReflowFlexItem(nsPresContext* aPresContext,
                      const FlexboxAxisTracker& aAxisTracker,
                      const ReflowInput& aReflowInput,
                      const FlexItem& aItem,
                      mozilla::LogicalPoint& aFramePos,
                      const nsSize& aContainerSize);

  /**
   * Helper-function to perform a "dummy reflow" on all our nsPlaceholderFrame
   * children, at the container's content-box origin.
   *
   * This doesn't actually represent the static position of the placeholders'
   * out-of-flow (OOF) frames -- we can't compute that until we've reflowed the
   * OOF, because (depending on the CSS Align properties) the static position
   * may be influenced by the OOF's size.  So for now, we just co-opt the
   * placeholder to store the flex container's logical content-box origin, and
   * we defer to nsAbsoluteContainingBlock to determine the OOF's actual static
   * position (using this origin, the OOF's size, and the CSS Align
   * properties).
   *
   * @param aPresContext       The presentation context being used in reflow.
   * @param aReflowInput       The flex container's reflow input.
   * @param aPlaceholders      An array of all the flex container's
   *                           nsPlaceholderFrame children.
   * @param aContentBoxOrigin  The flex container's logical content-box
   *                           origin (in its own coordinate space).
   * @param aContainerSize     The flex container's size (required by some
   *                           reflow methods to interpret positions correctly).
   */
  void ReflowPlaceholders(nsPresContext* aPresContext,
                          const ReflowInput& aReflowInput,
                          nsTArray<nsIFrame*>& aPlaceholders,
                          const mozilla::LogicalPoint& aContentBoxOrigin,
                          const nsSize& aContainerSize);

  /**
   * Helper for GetMinISize / GetPrefISize.
   */
  nscoord IntrinsicISize(gfxContext* aRenderingContext,
                         nsLayoutUtils::IntrinsicISizeType aType);

  /**
   * Cached values to optimize GetMinISize/GetPrefISize.
   */
  nscoord mCachedMinISize;
  nscoord mCachedPrefISize;

  nscoord mBaselineFromLastReflow;
  // Note: the last baseline is a distance from our border-box end edge.
  nscoord mLastBaselineFromLastReflow;
};

#endif /* nsFlexContainerFrame_h___ */