layout/base/nsFrameManager.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 /* Owns the frame tree and provides APIs to manipulate it */
   8
   9 #ifndef _nsFrameManager_h_
  10 #define _nsFrameManager_h_
  11
  12 #include "mozilla/Attributes.h"
  13 #include "nsDebug.h"
  14 #include "nsFrameList.h"
  15
  16 class nsContainerFrame;
  17 class nsIFrame;
  18 class nsILayoutHistoryState;
  19 class nsPlaceholderFrame;
  20 class nsWindowSizes;
  21
  22 namespace mozilla {
  23 struct FrameDestroyContext;
  24 class PresShell;
  25 class ViewportFrame;
  26 }  // namespace mozilla
  27
  28 /**
  29  * Frame manager interface. The frame manager owns the frame tree model, and
  30  * handles structural manipulations to it, such as appending and inserting a
  31  * list of frames to a parent frame, or removing a child frame from a parent
  32  * frame.
  33  */
  34 class nsFrameManager {
  35  public:
  36   using DestroyContext = mozilla::FrameDestroyContext;
  37
  38   explicit nsFrameManager(mozilla::PresShell* aPresShell)
  39       : mPresShell(aPresShell) {
  40     MOZ_ASSERT(mPresShell, "need a pres shell");
  41   }
  42   ~nsFrameManager();
  43
  44   /*
  45    * Gets and sets the root frame (i.e. ViewportFrame). The lifetime of the
  46    * root frame is controlled by the frame manager. When the frame manager is
  47    * destroyed, it destroys the entire frame hierarchy.
  48    */
  49   nsIFrame* GetRootFrame() const { return mRootFrame; }
  50   void SetRootFrame(mozilla::ViewportFrame* aRootFrame);
  51
  52   /*
  53    * After Destroy is called, it is an error to call any FrameManager methods.
  54    * Destroy should be called when the frame tree managed by the frame
  55    * manager is no longer being displayed.
  56    */
  57   void Destroy();
  58
  59   // Functions for manipulating the frame model
  60   void AppendFrames(nsContainerFrame* aParentFrame,
  61                     mozilla::FrameChildListID aListID,
  62                     nsFrameList&& aFrameList);
  63
  64   void InsertFrames(nsContainerFrame* aParentFrame,
  65                     mozilla::FrameChildListID aListID, nsIFrame* aPrevFrame,
  66                     nsFrameList&& aFrameList);
  67
  68   void RemoveFrame(DestroyContext&, mozilla::FrameChildListID, nsIFrame*);
  69
  70   /*
  71    * Capture/restore frame state for the frame subtree rooted at aFrame.
  72    * aState is the document state storage object onto which each frame
  73    * stores its state.  Callers of CaptureFrameState are responsible for
  74    * traversing next continuations of special siblings of aFrame as
  75    * needed; this method will only work with actual frametree descendants
  76    * of aFrame.
  77    */
  78
  79   void CaptureFrameState(nsIFrame* aFrame, nsILayoutHistoryState* aState);
  80
  81   void RestoreFrameState(nsIFrame* aFrame, nsILayoutHistoryState* aState);
  82
  83   /*
  84    * Add/restore state for one frame
  85    */
  86   void CaptureFrameStateFor(nsIFrame* aFrame, nsILayoutHistoryState* aState);
  87
  88   void RestoreFrameStateFor(nsIFrame* aFrame, nsILayoutHistoryState* aState);
  89
  90   void AddSizeOfIncludingThis(nsWindowSizes& aSizes) const;
  91
  92  protected:
  93   // weak link, because the pres shell owns us
  94   mozilla::PresShell* MOZ_NON_OWNING_REF mPresShell;
  95
  96   // Note: We use nsIFrame* instead of ViewportFrame* for mRootFrame to avoid
  97   // exposing ViewportFrame to the callers via GetRootFrame(), since they do not
  98   // depend on any ViewportFrame-specific APIs or details.
  99   nsIFrame* mRootFrame = nullptr;
 100 };
 101
 102 #endif