layout/generic/ColumnSetWrapperFrame.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
   6
   7 // A frame for CSS multi-column layout that wraps nsColumnSetFrames and
   8 // column-span frames.
   9
  10 #ifndef mozilla_ColumnSetWrapperFrame_h
  11 #define mozilla_ColumnSetWrapperFrame_h
  12
  13 #include "nsBlockFrame.h"
  14
  15 namespace mozilla {
  16
  17 class PresShell;
  18
  19 // This class is a wrapper for nsColumnSetFrames and column-span frame.
  20 // Essentially, we divide the *original* nsColumnSetFrame into multiple
  21 // nsColumnSetFrames on the basis of the number and position of spanning
  22 // elements.
  23 //
  24 // This wrapper is necessary for implementing column-span as it allows us to
  25 // maintain each nsColumnSetFrame as an independent set of columns, and each
  26 // column-span element then becomes just a block level element.
  27 //
  28 class ColumnSetWrapperFrame final : public nsBlockFrame {
  29  public:
  30   NS_DECL_FRAMEARENA_HELPERS(ColumnSetWrapperFrame)
  31   NS_DECL_QUERYFRAME
  32
  33   friend nsBlockFrame* ::NS_NewColumnSetWrapperFrame(
  34       mozilla::PresShell* aPresShell, ComputedStyle* aStyle,
  35       nsFrameState aStateFlags);
  36
  37   void Init(nsIContent* aContent, nsContainerFrame* aParent,
  38             nsIFrame* aPrevInFlow) override;
  39
  40   nsContainerFrame* GetContentInsertionFrame() override;
  41
  42   void AppendDirectlyOwnedAnonBoxes(nsTArray<OwnedAnonBox>& aResult) override;
  43
  44 #ifdef DEBUG_FRAME_DUMP
  45   nsresult GetFrameName(nsAString& aResult) const override;
  46 #endif
  47
  48   void AppendFrames(ChildListID aListID, nsFrameList&& aFrameList) override;
  49
  50   void InsertFrames(ChildListID aListID, nsIFrame* aPrevFrame,
  51                     const nsLineList::iterator* aPrevFrameLine,
  52                     nsFrameList&& aFrameList) override;
  53
  54   void RemoveFrame(DestroyContext&, ChildListID, nsIFrame*) override;
  55
  56   void MarkIntrinsicISizesDirty() override;
  57
  58   nscoord GetMinISize(gfxContext* aRenderingContext) override;
  59
  60   nscoord GetPrefISize(gfxContext* aRenderingContext) override;
  61
  62   Maybe<nscoord> GetNaturalBaselineBOffset(
  63       WritingMode aWM, BaselineSharingGroup aBaselineGroup,
  64       BaselineExportContext aExportContext) const override;
  65
  66  private:
  67   explicit ColumnSetWrapperFrame(ComputedStyle* aStyle,
  68                                  nsPresContext* aPresContext);
  69   ~ColumnSetWrapperFrame() override = default;
  70
  71 #ifdef DEBUG
  72   static void AssertColumnSpanWrapperSubtreeIsSane(const nsIFrame* aFrame);
  73
  74   // True if frame constructor has finished building this frame and all of
  75   // its descendants.
  76   bool mFinishedBuildingColumns = false;
  77 #endif
  78
  79   template <typename Iterator>
  80   Maybe<nscoord> GetBaselineBOffset(Iterator aStart, Iterator aEnd,
  81                                     WritingMode aWM,
  82                                     BaselineSharingGroup aBaselineGroup,
  83                                     BaselineExportContext aExportContext) const;
  84 };
  85
  86 }  // namespace mozilla
  87
  88 #endif  // mozilla_ColumnSetWrapperFrame_h