layout/base/DepthOrderedFrameList.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 #ifndef mozilla_DepthOrderedFrameList_h
   8 #define mozilla_DepthOrderedFrameList_h
   9
  10 #include "mozilla/ReverseIterator.h"
  11 #include "nsTArray.h"
  12
  13 class nsIFrame;
  14
  15 namespace mozilla {
  16
  17 class DepthOrderedFrameList {
  18  public:
  19   // Add a dirty root.
  20   void Add(nsIFrame* aFrame);
  21   // Remove this frame if present.
  22   void Remove(nsIFrame* aFrame);
  23   // Remove and return one of the shallowest dirty roots from the list.
  24   // (If two roots are at the same depth, order is indeterminate.)
  25   nsIFrame* PopShallowestRoot();
  26   // Remove all dirty roots.
  27   void Clear() { mList.Clear(); }
  28   // Is this frame one of the elements in the list?
  29   bool Contains(nsIFrame* aFrame) const { return mList.Contains(aFrame); }
  30   // Are there no elements?
  31   bool IsEmpty() const { return mList.IsEmpty(); }
  32
  33   // Is the given frame an ancestor of any dirty root?
  34   bool FrameIsAncestorOfAnyElement(nsIFrame* aFrame) const;
  35
  36   auto IterFromShallowest() const { return Reversed(mList); }
  37
  38  private:
  39   struct FrameAndDepth {
  40     nsIFrame* mFrame;
  41     const uint32_t mDepth;
  42
  43     // Easy conversion to nsIFrame*, as it's the most likely need.
  44     operator nsIFrame*() const { return mFrame; }
  45
  46     // Used to sort by reverse depths, i.e., deeper < shallower.
  47     class CompareByReverseDepth {
  48      public:
  49       bool Equals(const FrameAndDepth& aA, const FrameAndDepth& aB) const {
  50         return aA.mDepth == aB.mDepth;
  51       }
  52       bool LessThan(const FrameAndDepth& aA, const FrameAndDepth& aB) const {
  53         // Reverse depth! So '>' instead of '<'.
  54         return aA.mDepth > aB.mDepth;
  55       }
  56     };
  57   };
  58   // List of all known dirty roots, sorted by decreasing depths.
  59   nsTArray<FrameAndDepth> mList;
  60 };
  61
  62 }  // namespace mozilla
  63
  64 #endif