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 THIRD_PARTY_BLINK_RENDERER_CORE_PAINT_COMPOSITING_COMPOSITING_LAYER_ASSIGNER_H_
28 #define THIRD_PARTY_BLINK_RENDERER_CORE_PAINT_COMPOSITING_COMPOSITING_LAYER_ASSIGNER_H_
29 
30 #include "third_party/blink/renderer/core/paint/compositing/paint_layer_compositor.h"
31 #include "third_party/blink/renderer/platform/geometry/int_rect.h"
32 #include "third_party/blink/renderer/platform/geometry/layout_point.h"
33 #include "third_party/blink/renderer/platform/graphics/squashing_disallowed_reasons.h"
34 #include "third_party/blink/renderer/platform/wtf/allocator/allocator.h"
35 
36 namespace blink {
37 
38 class CompositedLayerMapping;
39 class PaintLayer;
40 
41 class CompositingLayerAssigner {
42   STACK_ALLOCATED();
43 
44  public:
45   explicit CompositingLayerAssigner(PaintLayerCompositor*);
46 
47   void Assign(PaintLayer* update_root,
48               Vector<PaintLayer*>& layers_needing_paint_invalidation);
49 
LayersChanged()50   bool LayersChanged() const { return layers_changed_; }
51 
52   // FIXME: This function should be private. We should remove the one caller
53   // once we've fixed the compositing chicken/egg issues.
54   CompositingStateTransitionType ComputeCompositedLayerUpdate(PaintLayer*);
55 
56  private:
57   struct SquashingState {
58     void UpdateSquashingStateForNewMapping(
59         CompositedLayerMapping*,
60         Vector<PaintLayer*>& layers_needing_paint_invalidation);
61 
62     // The most recent composited backing that the layer should squash onto if
63     // needed.
64     CompositedLayerMapping* most_recent_mapping = nullptr;
65 
66     // Whether all Layers in the stacking subtree rooted at the most recent
67     // mapping's owning layer have had CompositedLayerMappings assigned. Layers
68     // cannot squash into a CompositedLayerMapping owned by a stacking ancestor,
69     // since this changes paint order.
70     bool have_assigned_backings_to_entire_squashing_layer_subtree = false;
71 
72     // This is set to true when most_recent_mapping supports composited
73     // scrolling, and reset to false whenever any layer is not squashed into
74     // scrolling contents, to ensure all layers squashed into scrolling contents
75     // are continuous with the scroller in stacking order, without any other
76     // layer interlacing among them.
77     bool next_layer_may_squash_into_scrolling_contents = false;
78 
79     // Counter that tracks what index the next Layer would be if it gets
80     // squashed to the current non scrolling squashing layer.
81     wtf_size_t next_non_scrolling_squashed_layer_index = 0;
82     // Same as above but for layers squashed into scrolling contents layer.
83     wtf_size_t next_squashed_layer_in_scrolling_contents_index = 0;
84 
85     // The absolute bounding rect of all the squashed layers (not including
86     // those squashed into scrolling contents).
87     IntRect bounding_rect;
88 
89     // This is simply the sum of the areas of the squashed rects. This can be
90     // very skewed if the rects overlap, but should be close enough to drive a
91     // heuristic (not including those squashed into scrolling contents).
92     uint64_t total_area_of_squashed_rects = 0;
93   };
94 
95   void AssignLayersToBackingsInternal(
96       PaintLayer* layer,
97       PaintLayer* paint_invalidation_container,
98       SquashingState&,
99       Vector<PaintLayer*>& layers_needing_paint_invalidation);
100   SquashingDisallowedReasons GetReasonsPreventingSquashing(
101       const PaintLayer*,
102       const SquashingState&);
103   bool SquashingWouldExceedSparsityTolerance(const PaintLayer* candidate,
104                                              const SquashingState&);
105   void UpdateSquashingAssignment(
106       PaintLayer*,
107       SquashingState&,
108       CompositingStateTransitionType,
109       Vector<PaintLayer*>& layers_needing_paint_invalidation);
110   bool NeedsOwnBacking(const PaintLayer*) const;
111 
112   PaintLayerCompositor* compositor_;
113   bool layers_changed_;
114 };
115 
116 }  // namespace blink
117 
118 #endif  // THIRD_PARTY_BLINK_RENDERER_CORE_PAINT_COMPOSITING_COMPOSITING_LAYER_ASSIGNER_H_
119