third_party/WebKit/public/platform/WebDisplayItemTransformTree.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 WebDisplayItemTransformTree_h
   6 #define WebDisplayItemTransformTree_h
   7
   8 #include "public/platform/WebCommon.h"
   9 #include "public/platform/WebFloatSize.h"
  10 #include "public/platform/WebPrivateOwnPtr.h"
  11 #include "third_party/skia/include/core/SkPoint3.h"
  12 #include "third_party/skia/include/utils/SkMatrix44.h"
  13
  14 namespace blink {
  15
  16 class DisplayItemTransformTree;
  17
  18 // Represents the hierarchy of transforms which apply to ranges of a display
  19 // item list and may be of interest to the compositor.
  20 //
  21 // It consists of a tree of "transform nodes", stored in a flattened
  22 // representation in which their order is not guaranteed. Each node has a
  23 // parent, relative to whom its transform should be interpreted (i.e. the
  24 // total transform at a node is the product of its transform and its parent's
  25 // total transform).
  26 class BLINK_PLATFORM_EXPORT WebDisplayItemTransformTree {
  27 public:
  28     enum : size_t { kInvalidIndex = static_cast<size_t>(-1) };
  29
  30     struct TransformNode {
  31         TransformNode(size_t parent, const SkMatrix44& matrix44, const SkPoint3& origin)
  32             : parentNodeIndex(parent)
  33             , matrix(matrix44)
  34             , transformOrigin(origin)
  35         {
  36         }
  37
  38         bool isRoot() const { return parentNodeIndex == kInvalidIndex; }
  39
  40         // Index of parent in m_nodes (kInvalidIndex for root).
  41         size_t parentNodeIndex;
  42
  43         // Transformation matrix of this node, relative to its parent.
  44         SkMatrix44 matrix;
  45
  46         // Origin of the transform given by |matrix|.
  47         SkPoint3 transformOrigin;
  48     };
  49
  50     WebDisplayItemTransformTree();
  51 #if INSIDE_BLINK
  52     WebDisplayItemTransformTree(const WTF::PassOwnPtr<DisplayItemTransformTree>&);
  53 #endif
  54
  55     ~WebDisplayItemTransformTree();
  56
  57     // Returns the number of nodes in the transform tree.
  58     size_t nodeCount() const;
  59
  60     // Returns a node in the transform tree by its index (from 0 to nodeCount() - 1).
  61     const TransformNode& nodeAt(size_t index) const;
  62
  63 private:
  64     WebPrivateOwnPtr<const DisplayItemTransformTree> m_private;
  65 };
  66
  67 } // namespace blink
  68
  69 #endif // WebDisplayItemTransformTree_h