third_party/WebKit/public/platform/WebDisplayItemClipTree.h

   1 // Copyright 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef WebDisplayItemClipTree_h
   6 #define WebDisplayItemClipTree_h
   7
   8 #include "public/platform/WebCommon.h"
   9 #include "public/platform/WebFloatRect.h"
  10 #include "public/platform/WebPrivateOwnPtr.h"
  11
  12 namespace blink {
  13
  14 class DisplayItemClipTree;
  15
  16 // Represents a hierarchy of rectangular clips which apply to ranges of a
  17 // display list and may be of interest to the compositor.
  18 //
  19 // It consists of a tree of "transform nodes", stored in a flattened
  20 // representation in which their order is not guaranteed. Each node has a
  21 // parent (whose clip, and those of its ancestors, also apply to content),
  22 // a transform node index (into an associated |WebDisplayItemTransformTree|
  23 // which defines the coordinate space in which this clip is interpreted),
  24 // and a rectangle representing the clip.
  25 //
  26 // Rounded-rect clips are represented here by their bounding rect; the rounded
  27 // clip should be represented outside the clip tree (e.g. as a mask).
  28 class BLINK_PLATFORM_EXPORT WebDisplayItemClipTree {
  29 public:
  30     enum : size_t { kInvalidIndex = static_cast<size_t>(-1) };
  31
  32     struct ClipNode {
  33         ClipNode(size_t parent, size_t transformNodeIndex, const WebFloatRect& clipRect)
  34             : parentNodeIndex(parent)
  35             , transformNodeIndex(transformNodeIndex)
  36             , clipRect(clipRect)
  37         {
  38         }
  39
  40         bool isRoot() const { return parentNodeIndex == kInvalidIndex; }
  41
  42         // Index of parent in m_nodes (kInvalidIndex for root).
  43         size_t parentNodeIndex;
  44
  45         // Index of transform node in which this clip should be interpreted.
  46         // Cannot be WebDisplayItemTransformTree::kInvalidIndex.
  47         size_t transformNodeIndex;
  48
  49         // Rectangular clip in the space of the transform node.
  50         WebFloatRect clipRect;
  51     };
  52
  53     WebDisplayItemClipTree();
  54 #if INSIDE_BLINK
  55     WebDisplayItemClipTree(const WTF::PassOwnPtr<DisplayItemClipTree>&);
  56 #endif
  57
  58     ~WebDisplayItemClipTree();
  59
  60     // Returns the number of nodes in the clip tree.
  61     size_t nodeCount() const;
  62
  63     // Returns a node in the clip tree by its index (from 0 to nodeCount() - 1).
  64     const ClipNode& nodeAt(size_t index) const;
  65
  66 private:
  67     WebPrivateOwnPtr<const DisplayItemClipTree> m_private;
  68 };
  69
  70 } // namespace blink
  71
  72 #endif // WebDisplayItemClipTree_h