1/*
2 * Copyright (C) 2009, 2010 Apple Inc. All rights reserved.
3 * Copyright (C) 2014 Google Inc. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
15 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
17 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
18 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
19 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
20 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
21 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
22 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
24 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#ifndef CompositingLayerAssigner_h
28#define CompositingLayerAssigner_h
29
30#include "core/rendering/compositing/RenderLayerCompositor.h"
31#include "platform/geometry/IntRect.h"
32#include "platform/geometry/LayoutPoint.h"
33
34namespace blink {
35
36class RenderLayer;
37
38class CompositingLayerAssigner {
39public:
40    explicit CompositingLayerAssigner(RenderLayerCompositor*);
41    ~CompositingLayerAssigner();
42
43    void assign(RenderLayer* updateRoot, Vector<RenderLayer*>& layersNeedingPaintInvalidation);
44
45    bool layersChanged() const { return m_layersChanged; }
46
47    // FIXME: This function should be private. We should remove the one caller
48    // once we've fixed the compositing chicken/egg issues.
49    CompositingStateTransitionType computeCompositedLayerUpdate(RenderLayer*);
50
51private:
52    struct SquashingState {
53        SquashingState()
54            : mostRecentMapping(0)
55            , hasMostRecentMapping(false)
56            , haveAssignedBackingsToEntireSquashingLayerSubtree(false)
57            , nextSquashedLayerIndex(0)
58            , totalAreaOfSquashedRects(0) { }
59
60        void updateSquashingStateForNewMapping(CompositedLayerMapping*, bool hasNewCompositedLayerMapping);
61
62        // The most recent composited backing that the layer should squash onto if needed.
63        CompositedLayerMapping* mostRecentMapping;
64        bool hasMostRecentMapping;
65
66        // Whether all RenderLayers in the stacking subtree rooted at the most recent mapping's
67        // owning layer have had CompositedLayerMappings assigned. Layers cannot squash into a
68        // CompositedLayerMapping owned by a stacking ancestor, since this changes paint order.
69        bool haveAssignedBackingsToEntireSquashingLayerSubtree;
70
71        // Counter that tracks what index the next RenderLayer would be if it gets squashed to the current squashing layer.
72        size_t nextSquashedLayerIndex;
73
74        // The absolute bounding rect of all the squashed layers.
75        IntRect boundingRect;
76
77        // This is simply the sum of the areas of the squashed rects. This can be very skewed if the rects overlap,
78        // but should be close enough to drive a heuristic.
79        uint64_t totalAreaOfSquashedRects;
80    };
81
82    void assignLayersToBackingsInternal(RenderLayer*, SquashingState&, Vector<RenderLayer*>& layersNeedingPaintInvalidation);
83    void assignLayersToBackingsForReflectionLayer(RenderLayer* reflectionLayer, Vector<RenderLayer*>& layersNeedingPaintInvalidation);
84    CompositingReasons getReasonsPreventingSquashing(const RenderLayer*, const SquashingState&);
85    bool squashingWouldExceedSparsityTolerance(const RenderLayer* candidate, const SquashingState&);
86    void updateSquashingAssignment(RenderLayer*, SquashingState&, CompositingStateTransitionType, Vector<RenderLayer*>& layersNeedingPaintInvalidation);
87    bool needsOwnBacking(const RenderLayer*) const;
88
89    RenderLayerCompositor* m_compositor;
90    bool m_layerSquashingEnabled;
91    bool m_layersChanged;
92};
93
94} // namespace blink
95
96#endif // CompositingLayerAssigner_h
97