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      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 
     42 namespace blink {
     43 class GraphicsContext;
     44 
     45 enum 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.
     52 class PLATFORM_EXPORT RegionTracker FINAL {
     53 public:
     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 
    101 private:
    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