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	This prevents anonymous content getting destroyed at weird times during frame destruction. Differential Revision: https://phabricator.services.mozilla.com/D187693
		
			
				
	
	
		
			88 lines
		
	
	
	
		
			3 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			88 lines
		
	
	
	
		
			3 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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 * License, v. 2.0. If a copy of the MPL was not distributed with this
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 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
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// A frame for CSS multi-column layout that wraps nsColumnSetFrames and
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// column-span frames.
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#ifndef mozilla_ColumnSetWrapperFrame_h
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#define mozilla_ColumnSetWrapperFrame_h
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#include "nsBlockFrame.h"
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namespace mozilla {
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class PresShell;
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// This class is a wrapper for nsColumnSetFrames and column-span frame.
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// Essentially, we divide the *original* nsColumnSetFrame into multiple
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// nsColumnSetFrames on the basis of the number and position of spanning
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// elements.
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//
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// This wrapper is necessary for implementing column-span as it allows us to
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// maintain each nsColumnSetFrame as an independent set of columns, and each
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// column-span element then becomes just a block level element.
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//
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class ColumnSetWrapperFrame final : public nsBlockFrame {
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 public:
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  NS_DECL_FRAMEARENA_HELPERS(ColumnSetWrapperFrame)
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  NS_DECL_QUERYFRAME
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  friend nsBlockFrame* ::NS_NewColumnSetWrapperFrame(
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      mozilla::PresShell* aPresShell, ComputedStyle* aStyle,
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      nsFrameState aStateFlags);
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  void Init(nsIContent* aContent, nsContainerFrame* aParent,
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            nsIFrame* aPrevInFlow) override;
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  nsContainerFrame* GetContentInsertionFrame() override;
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  void AppendDirectlyOwnedAnonBoxes(nsTArray<OwnedAnonBox>& aResult) override;
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#ifdef DEBUG_FRAME_DUMP
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  nsresult GetFrameName(nsAString& aResult) const override;
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#endif
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  void AppendFrames(ChildListID aListID, nsFrameList&& aFrameList) override;
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  void InsertFrames(ChildListID aListID, nsIFrame* aPrevFrame,
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                    const nsLineList::iterator* aPrevFrameLine,
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                    nsFrameList&& aFrameList) override;
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  void RemoveFrame(DestroyContext&, ChildListID, nsIFrame*) override;
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  void MarkIntrinsicISizesDirty() override;
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  nscoord GetMinISize(gfxContext* aRenderingContext) override;
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  nscoord GetPrefISize(gfxContext* aRenderingContext) override;
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  Maybe<nscoord> GetNaturalBaselineBOffset(
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      WritingMode aWM, BaselineSharingGroup aBaselineGroup,
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      BaselineExportContext aExportContext) const override;
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 private:
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  explicit ColumnSetWrapperFrame(ComputedStyle* aStyle,
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                                 nsPresContext* aPresContext);
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  ~ColumnSetWrapperFrame() override = default;
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#ifdef DEBUG
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  static void AssertColumnSpanWrapperSubtreeIsSane(const nsIFrame* aFrame);
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  // True if frame constructor has finished building this frame and all of
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  // its descendants.
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  bool mFinishedBuildingColumns = false;
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#endif
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  template <typename Iterator>
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  Maybe<nscoord> GetBaselineBOffset(Iterator aStart, Iterator aEnd,
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                                    WritingMode aWM,
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                                    BaselineSharingGroup aBaselineGroup,
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                                    BaselineExportContext aExportContext) const;
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};
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}  // namespace mozilla
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#endif  // mozilla_ColumnSetWrapperFrame_h
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