SkDeferredCanvas.h revision 868074b50b0fc3e460d2aa97c1096827fe0a1935 
1/*
2 * Copyright 2012 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8#ifndef SkDeferredCanvas_DEFINED
9#define SkDeferredCanvas_DEFINED
10
11#include "SkCanvas.h"
12#include "SkPixelRef.h"
13
14class SkDeferredDevice;
15class SkImage;
16class SkSurface;
17
18/** \class SkDeferredCanvas
19    Subclass of SkCanvas that encapsulates an SkPicture or SkGPipe for deferred
20    drawing. The main difference between this class and SkPictureRecord (the
21    canvas provided by SkPicture) is that this is a full drop-in replacement
22    for SkCanvas, while SkPictureRecord only supports draw operations.
23    SkDeferredCanvas will transparently trigger the flushing of deferred
24    draw operations when an attempt is made to access the pixel data.
25*/
26class SK_API SkDeferredCanvas : public SkCanvas {
27public:
28    class SK_API NotificationClient;
29
30    /** Construct a canvas with the specified surface to draw into.
31        This factory must be used for newImageSnapshot to work.
32        @param surface Specifies a surface for the canvas to draw into.
33     */
34    static SkDeferredCanvas* Create(SkSurface* surface);
35
36//    static SkDeferredCanvas* Create(SkBaseDevice* device);
37
38    virtual ~SkDeferredCanvas();
39
40    /**
41     *  Specify the surface to be used by this canvas. Calling setSurface will
42     *  release the previously set surface or device. Takes a reference on the
43     *  surface.
44     *
45     *  @param surface The surface that the canvas will raw into
46     *  @return The surface argument, for convenience.
47     */
48    SkSurface* setSurface(SkSurface* surface);
49
50    /**
51     *  Specify a NotificationClient to be used by this canvas. Calling
52     *  setNotificationClient will release the previously set
53     *  NotificationClient, if any. SkDeferredCanvas does not take ownership
54     *  of the notification client.  Therefore user code is resposible
55     *  for its destruction.  The notification client must be unregistered
56     *  by calling setNotificationClient(NULL) if it is destroyed before
57     *  this canvas.
58     *  Note: Must be called after the device is set with setDevice.
59     *
60     *  @param notificationClient interface for dispatching notifications
61     *  @return The notificationClient argument, for convenience.
62     */
63    NotificationClient* setNotificationClient(NotificationClient* notificationClient);
64
65    /**
66     *  Enable or disable deferred drawing. When deferral is disabled,
67     *  pending draw operations are immediately flushed and from then on,
68     *  the SkDeferredCanvas behaves just like a regular SkCanvas.
69     *  This method must not be called while the save/restore stack is in use.
70     *  @param deferred true/false
71     */
72    void setDeferredDrawing(bool deferred);
73
74    /**
75     *  Returns true if deferred drawing is currenlty enabled.
76     */
77    bool isDeferredDrawing() const;
78
79    /**
80     *  Returns true if the canvas contains a fresh frame.  A frame is
81     *  considered fresh when its content do not depend on the contents
82     *  of the previous frame. For example, if a canvas is cleared before
83     *  drawing each frame, the frames will all be considered fresh.
84     *  A frame is defined as the graphics image produced by as a result
85     *  of all the canvas draws operation executed between two successive
86     *  calls to isFreshFrame.  The result of isFreshFrame is computed
87     *  conservatively, so it may report false negatives.
88     */
89    bool isFreshFrame() const;
90
91    /**
92     *  Returns true if the canvas has recorded draw commands that have
93     *  not yet been played back.
94     */
95    bool hasPendingCommands() const;
96
97    /**
98     *  Flushes pending draw commands, if any, and returns an image of the
99     *  current state of the surface pixels up to this point. Subsequent
100     *  changes to the surface (by drawing into its canvas) will not be
101     *  reflected in this image.  Will return NULL if the deferred canvas
102     *  was not constructed from an SkSurface.
103     */
104    SkImage* newImageSnapshot();
105
106    /**
107     *  Specify the maximum number of bytes to be allocated for the purpose
108     *  of recording draw commands to this canvas.  The default limit, is
109     *  64MB.
110     *  @param maxStorage The maximum number of bytes to be allocated.
111     */
112    void setMaxRecordingStorage(size_t maxStorage);
113
114    /**
115     *  Returns the number of bytes currently allocated for the purpose of
116     *  recording draw commands.
117     */
118    size_t storageAllocatedForRecording() const;
119
120    /**
121     * Attempt to reduce the storage allocated for recording by evicting
122     * cache resources.
123     * @param bytesToFree minimum number of bytes that should be attempted to
124     *   be freed.
125     * @return number of bytes actually freed.
126     */
127    size_t freeMemoryIfPossible(size_t bytesToFree);
128
129    /**
130     * Specifies the maximum size (in bytes) allowed for a given image to be
131     * rendered using the deferred canvas.
132     */
133    void setBitmapSizeThreshold(size_t sizeThreshold);
134
135    /**
136     * Executes all pending commands without drawing
137     */
138    void silentFlush();
139
140    // Overrides of the SkCanvas interface
141    virtual bool isDrawingToLayer() const SK_OVERRIDE;
142    virtual void clear(SkColor) SK_OVERRIDE;
143    virtual void drawPaint(const SkPaint& paint) SK_OVERRIDE;
144    virtual void drawPoints(PointMode mode, size_t count, const SkPoint pts[],
145                            const SkPaint& paint) SK_OVERRIDE;
146    virtual void drawOval(const SkRect&, const SkPaint& paint) SK_OVERRIDE;
147    virtual void drawRect(const SkRect& rect, const SkPaint& paint) SK_OVERRIDE;
148    virtual void drawRRect(const SkRRect&, const SkPaint& paint) SK_OVERRIDE;
149    virtual void drawPath(const SkPath& path, const SkPaint& paint)
150                          SK_OVERRIDE;
151    virtual void drawBitmap(const SkBitmap& bitmap, SkScalar left,
152                            SkScalar top, const SkPaint* paint)
153                            SK_OVERRIDE;
154    virtual void drawBitmapRectToRect(const SkBitmap& bitmap, const SkRect* src,
155                                      const SkRect& dst, const SkPaint* paint,
156                                      DrawBitmapRectFlags flags) SK_OVERRIDE;
157
158    virtual void drawBitmapMatrix(const SkBitmap& bitmap, const SkMatrix& m,
159                                  const SkPaint* paint) SK_OVERRIDE;
160    virtual void drawBitmapNine(const SkBitmap& bitmap, const SkIRect& center,
161                                const SkRect& dst, const SkPaint* paint)
162                                SK_OVERRIDE;
163    virtual void drawSprite(const SkBitmap& bitmap, int left, int top,
164                            const SkPaint* paint) SK_OVERRIDE;
165    virtual void drawPicture(SkPicture& picture) SK_OVERRIDE;
166    virtual void drawVertices(VertexMode vmode, int vertexCount,
167                              const SkPoint vertices[], const SkPoint texs[],
168                              const SkColor colors[], SkXfermode* xmode,
169                              const uint16_t indices[], int indexCount,
170                              const SkPaint& paint) SK_OVERRIDE;
171    virtual SkDrawFilter* setDrawFilter(SkDrawFilter* filter) SK_OVERRIDE;
172
173protected:
174    virtual void willSave(SaveFlags) SK_OVERRIDE;
175    virtual SaveLayerStrategy willSaveLayer(const SkRect*, const SkPaint*, SaveFlags) SK_OVERRIDE;
176    virtual void willRestore() SK_OVERRIDE;
177
178    virtual void didConcat(const SkMatrix&) SK_OVERRIDE;
179    virtual void didSetMatrix(const SkMatrix&) SK_OVERRIDE;
180
181    virtual void onDrawDRRect(const SkRRect&, const SkRRect&, const SkPaint&) SK_OVERRIDE;
182    virtual void onDrawText(const void* text, size_t byteLength, SkScalar x, SkScalar y,
183                            const SkPaint&) SK_OVERRIDE;
184    virtual void onDrawPosText(const void* text, size_t byteLength, const SkPoint pos[],
185                               const SkPaint&) SK_OVERRIDE;
186    virtual void onDrawPosTextH(const void* text, size_t byteLength, const SkScalar xpos[],
187                                SkScalar constY, const SkPaint&) SK_OVERRIDE;
188    virtual void onDrawTextOnPath(const void* text, size_t byteLength, const SkPath& path,
189                                  const SkMatrix* matrix, const SkPaint&) SK_OVERRIDE;
190
191    virtual void onClipRect(const SkRect&, SkRegion::Op, ClipEdgeStyle) SK_OVERRIDE;
192    virtual void onClipRRect(const SkRRect&, SkRegion::Op, ClipEdgeStyle) SK_OVERRIDE;
193    virtual void onClipPath(const SkPath&, SkRegion::Op, ClipEdgeStyle) SK_OVERRIDE;
194    virtual void onClipRegion(const SkRegion&, SkRegion::Op) SK_OVERRIDE;
195
196public:
197    class NotificationClient {
198    public:
199        virtual ~NotificationClient() {}
200
201        /**
202         *  Called before executing one or several draw commands, which means
203         *  once per flush when deferred rendering is enabled.
204         */
205        virtual void prepareForDraw() {}
206
207        /**
208         *  Called after a recording a draw command if additional memory
209         *  had to be allocated for recording.
210         *  @param newAllocatedStorage same value as would be returned by
211         *      storageAllocatedForRecording(), for convenience.
212         */
213        virtual void storageAllocatedForRecordingChanged(
214            size_t newAllocatedStorage) {}
215
216        /**
217         *  Called after pending draw commands have been flushed
218         */
219        virtual void flushedDrawCommands() {}
220
221        /**
222         *  Called after pending draw commands have been skipped, meaning
223         *  that they were optimized-out because the canvas is cleared
224         *  or completely overwritten by the command currently being recorded.
225         */
226        virtual void skippedPendingDrawCommands() {}
227    };
228
229protected:
230    virtual SkCanvas* canvasForDrawIter();
231    SkDeferredDevice* getDeferredDevice() const;
232
233private:
234    SkDeferredCanvas(SkDeferredDevice*);
235
236    void recordedDrawCommand();
237    SkCanvas* drawingCanvas() const;
238    SkCanvas* immediateCanvas() const;
239    bool isFullFrame(const SkRect*, const SkPaint*) const;
240    void validate() const;
241    void init();
242    bool            fDeferredDrawing;
243
244    friend class SkDeferredCanvasTester; // for unit testing
245    typedef SkCanvas INHERITED;
246};
247
248
249#endif
250