layout/generic/ViewportFrame.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 http://mozilla.org/MPL/2.0/. */
   6
   7 /*
   8  * rendering object that is the root of the frame tree, which contains
   9  * the document's scrollbars and contains fixed-positioned elements
  10  */
  11
  12 #ifndef mozilla_ViewportFrame_h
  13 #define mozilla_ViewportFrame_h
  14
  15 #include "mozilla/Attributes.h"
  16 #include "nsContainerFrame.h"
  17
  18 class nsPresContext;
  19
  20 namespace mozilla {
  21
  22 class nsDisplayWrapList;
  23 class ServoRestyleState;
  24
  25 /**
  26  * ViewportFrame is the parent of a single child - the doc root frame or a
  27  * scroll frame containing the doc root frame. ViewportFrame stores this child
  28  * in its primary child list.
  29  */
  30 class ViewportFrame : public nsContainerFrame {
  31  public:
  32   NS_DECL_QUERYFRAME
  33   NS_DECL_FRAMEARENA_HELPERS(ViewportFrame)
  34
  35   explicit ViewportFrame(ComputedStyle* aStyle, nsPresContext* aPresContext)
  36       : ViewportFrame(aStyle, aPresContext, kClassID) {}
  37
  38   virtual ~ViewportFrame() = default;  // useful for debugging
  39
  40   void Init(nsIContent* aContent, nsContainerFrame* aParent,
  41             nsIFrame* aPrevInFlow) override;
  42
  43 #ifdef DEBUG
  44   void AppendFrames(ChildListID aListID, nsFrameList&& aFrameList) override;
  45   void InsertFrames(ChildListID aListID, nsIFrame* aPrevFrame,
  46                     const nsLineList::iterator* aPrevFrameLine,
  47                     nsFrameList&& aFrameList) override;
  48   void RemoveFrame(DestroyContext&, ChildListID, nsIFrame*) override;
  49 #endif
  50
  51   void BuildDisplayList(nsDisplayListBuilder* aBuilder,
  52                         const nsDisplayListSet& aLists) override;
  53
  54   nsDisplayWrapList* BuildDisplayListForTopLayer(nsDisplayListBuilder* aBuilder,
  55                                                  bool* aIsOpaque = nullptr);
  56
  57   nscoord GetMinISize(gfxContext* aRenderingContext) override;
  58   nscoord GetPrefISize(gfxContext* aRenderingContext) override;
  59   void Reflow(nsPresContext* aPresContext, ReflowOutput& aDesiredSize,
  60               const ReflowInput& aReflowInput,
  61               nsReflowStatus& aStatus) override;
  62
  63   bool ComputeCustomOverflow(mozilla::OverflowAreas&) override { return false; }
  64
  65   /**
  66    * Adjust aReflowInput to account for scrollbars and pres shell
  67    * GetVisualViewportSizeSet and
  68    * GetContentDocumentFixedPositionMargins adjustments.
  69    * @return the rect to use as containing block rect
  70    */
  71   nsRect AdjustReflowInputAsContainingBlock(ReflowInput* aReflowInput) const;
  72
  73   /**
  74    * Update our style (and recursively the styles of any anonymous boxes we
  75    * might own)
  76    */
  77   void UpdateStyle(ServoRestyleState& aStyleSet);
  78
  79   /**
  80    * Return our single anonymous box child.
  81    */
  82   void AppendDirectlyOwnedAnonBoxes(nsTArray<OwnedAnonBox>& aResult) override;
  83
  84   // Returns adjusted viewport size to reflect the positions that position:fixed
  85   // elements are attached.
  86   nsSize AdjustViewportSizeForFixedPosition(const nsRect& aViewportRect) const;
  87
  88 #ifdef DEBUG_FRAME_DUMP
  89   virtual nsresult GetFrameName(nsAString& aResult) const override;
  90 #endif
  91
  92  protected:
  93   ViewportFrame(ComputedStyle* aStyle, nsPresContext* aPresContext, ClassID aID)
  94       : nsContainerFrame(aStyle, aPresContext, aID), mView(nullptr) {}
  95
  96   /**
  97    * Calculate how much room is available for fixed frames. That means
  98    * determining if the viewport is scrollable and whether the vertical and/or
  99    * horizontal scrollbars are visible.  Adjust the computed width/height and
 100    * available width for aReflowInput accordingly.
 101    * @return the current scroll position, or 0,0 if not scrollable
 102    */
 103   nsPoint AdjustReflowInputForScrollbars(ReflowInput* aReflowInput) const;
 104
 105   nsView* GetViewInternal() const override { return mView; }
 106   void SetViewInternal(nsView* aView) override { mView = aView; }
 107
 108  private:
 109   mozilla::FrameChildListID GetAbsoluteListID() const override {
 110     return FrameChildListID::Fixed;
 111   }
 112
 113   nsView* mView;
 114 };
 115
 116 }  // namespace mozilla
 117
 118 #endif  // mozilla_ViewportFrame_h