ColumnSetWrapperFrame.h

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/* -*- 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 https://mozilla.org/MPL/2.0/. */

// A frame for CSS multi-column layout that wraps nsColumnSetFrames and

// column-span frames.

#ifndef mozilla_ColumnSetWrapperFrame_h

#define mozilla_ColumnSetWrapperFrame_h

#include "nsBlockFrame.h"

namespace mozilla {

class PresShell;

// This class is a wrapper for nsColumnSetFrames and column-span frame.

// Essentially, we divide the *original* nsColumnSetFrame into multiple

// nsColumnSetFrames on the basis of the number and position of spanning

// elements.

//

// This wrapper is necessary for implementing column-span as it allows us to

// maintain each nsColumnSetFrame as an independent set of columns, and each

// column-span element then becomes just a block level element.

//

class ColumnSetWrapperFrame final : public nsBlockFrame {

 public:

  NS_DECL_FRAMEARENA_HELPERS(ColumnSetWrapperFrame)

  NS_DECL_QUERYFRAME

  friend nsBlockFrame* ::NS_NewColumnSetWrapperFrame(

      mozilla::PresShell* aPresShell, ComputedStyle* aStyle,

      nsFrameState aStateFlags);

  void Init(nsIContent* aContent, nsContainerFrame* aParent,

            nsIFrame* aPrevInFlow) override;

  nsContainerFrame* GetContentInsertionFrame() override;

  void AppendDirectlyOwnedAnonBoxes(nsTArray<OwnedAnonBox>& aResult) override;

#ifdef DEBUG_FRAME_DUMP

  nsresult GetFrameName(nsAString& aResult) const override;

#endif

  void AppendFrames(ChildListID aListID, nsFrameList&& aFrameList) override;

  void InsertFrames(ChildListID aListID, nsIFrame* aPrevFrame,

                    const nsLineList::iterator* aPrevFrameLine,

                    nsFrameList&& aFrameList) override;

  void RemoveFrame(DestroyContext&, ChildListID, nsIFrame*) override;

  void MarkIntrinsicISizesDirty() override;

  nscoord IntrinsicISize(const IntrinsicSizeInput& aInput,

                         IntrinsicISizeType aType) override;

  Maybe<nscoord> GetNaturalBaselineBOffset(

      WritingMode aWM, BaselineSharingGroup aBaselineGroup,

      BaselineExportContext aExportContext) const override;

 private:

  explicit ColumnSetWrapperFrame(ComputedStyle* aStyle,

                                 nsPresContext* aPresContext);

  ~ColumnSetWrapperFrame() override = default;

  // MinISize() and PrefISize() are helpers to implement IntrinsicISize().

  nscoord MinISize(const IntrinsicSizeInput& aInput);

  nscoord PrefISize(const IntrinsicSizeInput& aInput);

#ifdef DEBUG

  static void AssertColumnSpanWrapperSubtreeIsSane(const nsIFrame* aFrame);

  // True if frame constructor has finished building this frame and all of

  // its descendants.

  bool mFinishedBuildingColumns = false;

#endif

  template <typename Iterator>

  Maybe<nscoord> GetBaselineBOffset(Iterator aStart, Iterator aEnd,

                                    WritingMode aWM,

                                    BaselineSharingGroup aBaselineGroup,

                                    BaselineExportContext aExportContext) const;

};

}  // namespace mozilla

#endif  // mozilla_ColumnSetWrapperFrame_h