341 lines
15 KiB
C++
341 lines
15 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code is subject to the terms of the Mozilla Public License
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* version 2.0 (the "License"). You can obtain a copy of the License at
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* http://mozilla.org/MPL/2.0/. */
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/* rendering object for CSS "display: flex" and "display: -webkit-box" */
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#ifndef nsFlexContainerFrame_h___
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#define nsFlexContainerFrame_h___
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#include "nsContainerFrame.h"
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#include "mozilla/UniquePtr.h"
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namespace mozilla {
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template <class T> class LinkedList;
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class LogicalPoint;
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} // namespace mozilla
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nsContainerFrame* NS_NewFlexContainerFrame(nsIPresShell* aPresShell,
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nsStyleContext* aContext);
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/**
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* This is the rendering object used for laying out elements with
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* "display: flex" or "display: inline-flex".
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*
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* We also use this class for elements with "display: -webkit-box" or
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* "display: -webkit-inline-box" (but not "-moz-box" / "-moz-inline-box" --
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* those are rendered with old-school XUL frame classes).
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*
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* Note: we represent the -webkit-box family of properties (-webkit-box-orient,
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* -webkit-box-flex, etc.) as aliases for their -moz equivalents. And for
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* -webkit-{inline-}box containers, nsFlexContainerFrame will honor those
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* "legacy" properties for alignment/flexibility/etc. *instead of* honoring the
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* modern flexbox & alignment properties. For brevity, many comments in
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* nsFlexContainerFrame.cpp simply refer to these properties using their
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* "-webkit" versions, since we're mostly expecting to encounter them in that
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* form. (Technically, the "-moz" versions of these properties *can* influence
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* layout here as well (since that's what the -webkit versions are aliased to)
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* -- but only inside of a "display:-webkit-{inline-}box" container.)
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*/
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class nsFlexContainerFrame : public nsContainerFrame {
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public:
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NS_DECL_FRAMEARENA_HELPERS
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NS_DECL_QUERYFRAME_TARGET(nsFlexContainerFrame)
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NS_DECL_QUERYFRAME
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// Factory method:
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friend nsContainerFrame* NS_NewFlexContainerFrame(nsIPresShell* aPresShell,
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nsStyleContext* aContext);
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// Forward-decls of helper classes
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class FlexItem;
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class FlexLine;
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class FlexboxAxisTracker;
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struct StrutInfo;
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class CachedMeasuringReflowResult;
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// nsIFrame overrides
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void Init(nsIContent* aContent,
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nsContainerFrame* aParent,
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nsIFrame* aPrevInFlow) override;
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virtual void BuildDisplayList(nsDisplayListBuilder* aBuilder,
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const nsDisplayListSet& aLists) override;
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void MarkIntrinsicISizesDirty() override;
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virtual void Reflow(nsPresContext* aPresContext,
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ReflowOutput& aDesiredSize,
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const ReflowInput& aReflowInput,
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nsReflowStatus& aStatus) override;
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virtual nscoord
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GetMinISize(nsRenderingContext* aRenderingContext) override;
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virtual nscoord
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GetPrefISize(nsRenderingContext* aRenderingContext) override;
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virtual nsIAtom* GetType() const override;
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#ifdef DEBUG_FRAME_DUMP
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virtual nsresult GetFrameName(nsAString& aResult) const override;
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#endif
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nscoord GetLogicalBaseline(mozilla::WritingMode aWM) const override;
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bool GetVerticalAlignBaseline(mozilla::WritingMode aWM,
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nscoord* aBaseline) const override
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{
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return GetNaturalBaselineBOffset(aWM, BaselineSharingGroup::eFirst, aBaseline);
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}
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bool GetNaturalBaselineBOffset(mozilla::WritingMode aWM,
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BaselineSharingGroup aBaselineGroup,
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nscoord* aBaseline) const override
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{
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if (HasAnyStateBits(NS_STATE_FLEX_SYNTHESIZE_BASELINE)) {
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return false;
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}
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*aBaseline = aBaselineGroup == BaselineSharingGroup::eFirst ?
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mBaselineFromLastReflow : mLastBaselineFromLastReflow;
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return true;
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}
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// nsContainerFrame overrides
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uint16_t CSSAlignmentForAbsPosChild(
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const ReflowInput& aChildRI,
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mozilla::LogicalAxis aLogicalAxis) const override;
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// Flexbox-specific public methods
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bool IsHorizontal();
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/**
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* Helper function to calculate packing space and initial offset of alignment
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* subjects in MainAxisPositionTracker() and CrossAxisPositionTracker() for
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* space-between, space-around, and space-evenly.
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*
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* @param aNumThingsToPack Number of alignment subjects.
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* @param aAlignVal Value for align-self or justify-self.
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* @param aFirstSubjectOffset Outparam for first subject offset.
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* @param aNumPackingSpacesRemaining Outparam for number of equal-sized
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* packing spaces to apply between each
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* alignment subject.
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* @param aPackingSpaceRemaining Outparam for total amount of packing
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* space to be divided up.
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*/
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static void CalculatePackingSpace(uint32_t aNumThingsToPack,
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uint8_t aAlignVal,
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nscoord* aFirstSubjectOffset,
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uint32_t* aNumPackingSpacesRemaining,
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nscoord* aPackingSpaceRemaining);
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protected:
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// Protected constructor & destructor
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explicit nsFlexContainerFrame(nsStyleContext* aContext)
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: nsContainerFrame(aContext)
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, mBaselineFromLastReflow(NS_INTRINSIC_WIDTH_UNKNOWN)
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, mLastBaselineFromLastReflow(NS_INTRINSIC_WIDTH_UNKNOWN)
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{}
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virtual ~nsFlexContainerFrame();
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/*
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* This method does the bulk of the flex layout, implementing the algorithm
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* described at:
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* http://dev.w3.org/csswg/css-flexbox/#layout-algorithm
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* (with a few initialization pieces happening in the caller, Reflow().
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*
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* Since this is a helper for Reflow(), this takes all the same parameters
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* as Reflow(), plus a few more parameters that Reflow() sets up for us.
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*
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* (The logic behind the division of work between Reflow and DoFlexLayout is
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* as follows: DoFlexLayout() begins at the step that we have to jump back
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* to, if we find any visibility:collapse children, and Reflow() does
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* everything before that point.)
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*/
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void DoFlexLayout(nsPresContext* aPresContext,
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ReflowOutput& aDesiredSize,
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const ReflowInput& aReflowInput,
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nsReflowStatus& aStatus,
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nscoord aContentBoxMainSize,
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nscoord aAvailableBSizeForContent,
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nsTArray<StrutInfo>& aStruts,
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const FlexboxAxisTracker& aAxisTracker);
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/**
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* Checks whether our child-frame list "mFrames" is sorted, using the given
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* IsLessThanOrEqual function, and sorts it if it's not already sorted.
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*
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* XXXdholbert Once we support pagination, we need to make this function
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* check our continuations as well (or wrap it in a function that does).
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*
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* @return true if we had to sort mFrames, false if it was already sorted.
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*/
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template<bool IsLessThanOrEqual(nsIFrame*, nsIFrame*)>
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bool SortChildrenIfNeeded();
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// Protected flex-container-specific methods / member-vars
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#ifdef DEBUG
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void SanityCheckAnonymousFlexItems() const;
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#endif // DEBUG
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/*
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* Returns a new FlexItem for the given child frame, allocated on the heap.
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* Guaranteed to return non-null. Caller is responsible for managing the
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* FlexItem's lifetime.
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*
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* Before returning, this method also processes the FlexItem to resolve its
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* flex basis (including e.g. auto-height) as well as to resolve
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* "min-height:auto", via ResolveAutoFlexBasisAndMinSize(). (Basically, the
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* returned FlexItem will be ready to participate in the "Resolve the
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* Flexible Lengths" step of the Flex Layout Algorithm.)
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*/
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mozilla::UniquePtr<FlexItem> GenerateFlexItemForChild(nsPresContext* aPresContext,
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nsIFrame* aChildFrame,
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const ReflowInput& aParentReflowInput,
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const FlexboxAxisTracker& aAxisTracker);
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/**
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* This method gets a cached measuring reflow for a flex item, or does it and
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* caches it.
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*
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* This avoids exponential reflows, see the comment on
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* CachedMeasuringReflowResult.
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*/
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const CachedMeasuringReflowResult& MeasureAscentAndHeightForFlexItem(
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FlexItem& aItem,
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nsPresContext* aPresContext,
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ReflowInput& aChildReflowInput);
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/**
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* This method performs a "measuring" reflow to get the content height of
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* aFlexItem.Frame() (treating it as if it had auto-height), & returns the
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* resulting height.
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* (Helper for ResolveAutoFlexBasisAndMinSize().)
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*/
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nscoord MeasureFlexItemContentHeight(nsPresContext* aPresContext,
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FlexItem& aFlexItem,
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bool aForceVerticalResizeForMeasuringReflow,
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const ReflowInput& aParentReflowInput);
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/**
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* This method resolves an "auto" flex-basis and/or min-main-size value
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* on aFlexItem, if needed.
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* (Helper for GenerateFlexItemForChild().)
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*/
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void ResolveAutoFlexBasisAndMinSize(nsPresContext* aPresContext,
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FlexItem& aFlexItem,
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const ReflowInput& aItemReflowInput,
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const FlexboxAxisTracker& aAxisTracker);
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/**
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* This method:
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* - Creates FlexItems for all of our child frames (except placeholders).
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* - Groups those FlexItems into FlexLines.
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* - Returns those FlexLines in the outparam |aLines|.
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*
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* For any child frames which are placeholders, this method will instead just
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* append that child to the outparam |aPlaceholders| for separate handling.
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* (Absolutely positioned children of a flex container are *not* flex items.)
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*/
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void GenerateFlexLines(nsPresContext* aPresContext,
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const ReflowInput& aReflowInput,
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nscoord aContentBoxMainSize,
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nscoord aAvailableBSizeForContent,
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const nsTArray<StrutInfo>& aStruts,
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const FlexboxAxisTracker& aAxisTracker,
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nsTArray<nsIFrame*>& aPlaceholders,
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mozilla::LinkedList<FlexLine>& aLines);
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nscoord GetMainSizeFromReflowInput(const ReflowInput& aReflowInput,
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const FlexboxAxisTracker& aAxisTracker);
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nscoord ComputeCrossSize(const ReflowInput& aReflowInput,
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const FlexboxAxisTracker& aAxisTracker,
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nscoord aSumLineCrossSizes,
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nscoord aAvailableBSizeForContent,
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bool* aIsDefinite,
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nsReflowStatus& aStatus);
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void SizeItemInCrossAxis(nsPresContext* aPresContext,
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const FlexboxAxisTracker& aAxisTracker,
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ReflowInput& aChildReflowInput,
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FlexItem& aItem);
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/**
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* Moves the given flex item's frame to the given LogicalPosition (modulo any
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* relative positioning).
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*
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* This can be used in cases where we've already done a "measuring reflow"
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* for the flex item at the correct size, and hence can skip its final reflow
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* (but still need to move it to the right final position).
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*
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* @param aReflowInput The flex container's reflow state.
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* @param aItem The flex item whose frame should be moved.
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* @param aFramePos The position where the flex item's frame should
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* be placed. (pre-relative positioning)
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* @param aContainerSize The flex container's size (required by some methods
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* that we call, to interpret aFramePos correctly).
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*/
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void MoveFlexItemToFinalPosition(const ReflowInput& aReflowInput,
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const FlexItem& aItem,
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mozilla::LogicalPoint& aFramePos,
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const nsSize& aContainerSize);
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/**
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* Helper-function to reflow a child frame, at its final position determined
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* by flex layout.
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*
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* @param aPresContext The presentation context being used in reflow.
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* @param aAxisTracker A FlexboxAxisTracker with the flex container's axes.
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* @param aReflowInput The flex container's reflow state.
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* @param aItem The flex item to be reflowed.
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* @param aFramePos The position where the flex item's frame should
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* be placed. (pre-relative positioning)
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* @param aContainerSize The flex container's size (required by some methods
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* that we call, to interpret aFramePos correctly).
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*/
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void ReflowFlexItem(nsPresContext* aPresContext,
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const FlexboxAxisTracker& aAxisTracker,
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const ReflowInput& aReflowInput,
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const FlexItem& aItem,
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mozilla::LogicalPoint& aFramePos,
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const nsSize& aContainerSize);
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/**
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* Helper-function to perform a "dummy reflow" on all our nsPlaceholderFrame
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* children, at the container's content-box origin.
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*
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* This doesn't actually represent the static position of the placeholders'
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* out-of-flow (OOF) frames -- we can't compute that until we've reflowed the
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* OOF, because (depending on the CSS Align properties) the static position
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* may be influenced by the OOF's size. So for now, we just co-opt the
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* placeholder to store the flex container's logical content-box origin, and
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* we defer to nsAbsoluteContainingBlock to determine the OOF's actual static
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* position (using this origin, the OOF's size, and the CSS Align
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* properties).
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*
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* @param aPresContext The presentation context being used in reflow.
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* @param aReflowInput The flex container's reflow input.
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* @param aPlaceholders An array of all the flex container's
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* nsPlaceholderFrame children.
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* @param aContentBoxOrigin The flex container's logical content-box
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* origin (in its own coordinate space).
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* @param aContainerSize The flex container's size (required by some
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* reflow methods to interpret positions correctly).
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*/
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void ReflowPlaceholders(nsPresContext* aPresContext,
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const ReflowInput& aReflowInput,
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nsTArray<nsIFrame*>& aPlaceholders,
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const mozilla::LogicalPoint& aContentBoxOrigin,
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const nsSize& aContainerSize);
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bool mChildrenHaveBeenReordered; // Have we ever had to reorder our kids
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// to satisfy their 'order' values?
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nscoord mBaselineFromLastReflow;
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// Note: the last baseline is a distance from our border-box end edge.
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nscoord mLastBaselineFromLastReflow;
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};
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#endif /* nsFlexContainerFrame_h___ */
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