1/*
2 * Copyright (c) 2012, Google Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions are
6 * met:
7 *
8 *     * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 *     * Redistributions in binary form must reproduce the above
11 * copyright notice, this list of conditions and the following disclaimer
12 * in the documentation and/or other materials provided with the
13 * distribution.
14 *     * Neither the name of Google Inc. nor the names of its
15 * contributors may be used to endorse or promote products derived from
16 * this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31#ifndef RegionTracker_h
32#define RegionTracker_h
33
34#include "platform/PlatformExport.h"
35#include "platform/geometry/IntRect.h"
36#include "third_party/skia/include/core/SkBitmap.h"
37#include "third_party/skia/include/core/SkCanvas.h"
38#include "third_party/skia/include/core/SkPaint.h"
39#include "third_party/skia/include/core/SkPoint.h"
40#include "third_party/skia/include/core/SkRect.h"
41
42namespace blink {
43class GraphicsContext;
44
45enum RegionTrackingMode {
46    TrackOpaqueRegion,
47    TRackOverwriteRegion
48};
49
50// This class is an encapsulation of functionality for GraphicsContext, and its methods are mirrored
51// there for the outside world. It tracks paints and computes what area will be opaque.
52class PLATFORM_EXPORT RegionTracker FINAL {
53public:
54    RegionTracker();
55
56    // The resulting opaque region as a single rect.
57    IntRect asRect() const;
58
59    void pushCanvasLayer(const SkPaint*);
60    void popCanvasLayer(const GraphicsContext*);
61
62    void setImageMask(const SkRect& imageOpaqueRect);
63
64    enum RegionType {
65        Opaque,
66        Overwrite
67    };
68
69    // Set this to true to track regions that occlude the destination instead of only regions that produce opaque pixels.
70    void setTrackedRegionType(RegionType type) { m_trackedRegionType = type; }
71
72    enum DrawType {
73        FillOnly,
74        FillOrStroke
75    };
76
77    void didDrawRect(const GraphicsContext*, const SkRect&, const SkPaint&, const SkBitmap* sourceBitmap);
78    void didDrawPath(const GraphicsContext*, const SkPath&, const SkPaint&);
79    void didDrawPoints(const GraphicsContext*, SkCanvas::PointMode, int numPoints, const SkPoint[], const SkPaint&);
80    void didDrawBounded(const GraphicsContext*, const SkRect&, const SkPaint&);
81    void didDrawUnbounded(const GraphicsContext*, const SkPaint&, DrawType);
82
83    struct CanvasLayerState {
84        CanvasLayerState()
85            : hasImageMask(false)
86            , opaqueRect(SkRect::MakeEmpty())
87        { }
88
89        SkPaint paint;
90
91        // An image mask is being applied to the layer.
92        bool hasImageMask;
93        // The opaque area in the image mask.
94        SkRect imageOpaqueRect;
95
96        SkRect opaqueRect;
97    };
98
99    void reset();
100
101private:
102    void didDraw(const GraphicsContext*, const SkRect&, const SkPaint&, const SkBitmap* sourceBitmap, bool fillsBounds, DrawType);
103    void applyOpaqueRegionFromLayer(const GraphicsContext*, const SkRect& layerOpaqueRect, const SkPaint&);
104    void markRectAsOpaque(const SkRect&);
105    void markRectAsNonOpaque(const SkRect&);
106    void markAllAsNonOpaque();
107
108    SkRect& currentTrackingOpaqueRect();
109
110    SkRect m_opaqueRect;
111    RegionType m_trackedRegionType;
112
113    Vector<CanvasLayerState, 3> m_canvasLayerStack;
114};
115
116} // namespace blink
117
118#endif // RegionTracker_h
119