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1 
2 /*
3  * Copyright 2007 The Android Open Source Project
4  *
5  * Use of this source code is governed by a BSD-style license that can be
6  * found in the LICENSE file.
7  */
8 
9 
10 #ifndef SkPicture_DEFINED
11 #define SkPicture_DEFINED
12 
13 #include "SkBitmap.h"
14 #include "SkImageDecoder.h"
15 #include "SkRefCnt.h"
16 
17 class SkBBoxHierarchy;
18 class SkCanvas;
19 class SkDrawPictureCallback;
20 class SkData;
21 class SkPicturePlayback;
22 class SkPictureRecord;
23 class SkStream;
24 class SkWStream;
25 
26 struct SkPictInfo;
27 
28 /** \class SkPicture
29 
30     The SkPicture class records the drawing commands made to a canvas, to
31     be played back at a later time.
32 */
33 class SK_API SkPicture : public SkRefCnt {
34 public:
35     SK_DECLARE_INST_COUNT(SkPicture)
36 
37     /** The constructor prepares the picture to record.
38         @param width the width of the virtual device the picture records.
39         @param height the height of the virtual device the picture records.
40     */
41     SkPicture();
42     /** Make a copy of the contents of src. If src records more drawing after
43         this call, those elements will not appear in this picture.
44     */
45     SkPicture(const SkPicture& src);
46 
47     /**
48      *  Function signature defining a function that sets up an SkBitmap from encoded data. On
49      *  success, the SkBitmap should have its Config, width, height, rowBytes and pixelref set.
50      *  If the installed pixelref has decoded the data into pixels, then the src buffer need not be
51      *  copied. If the pixelref defers the actual decode until its lockPixels() is called, then it
52      *  must make a copy of the src buffer.
53      *  @param src Encoded data.
54      *  @param length Size of the encoded data, in bytes.
55      *  @param dst SkBitmap to install the pixel ref on.
56      *  @param bool Whether or not a pixel ref was successfully installed.
57      */
58     typedef bool (*InstallPixelRefProc)(const void* src, size_t length, SkBitmap* dst);
59 
60     /**
61      *  Recreate a picture that was serialized into a stream.
62      *  @param SkStream Serialized picture data.
63      *  @param proc Function pointer for installing pixelrefs on SkBitmaps representing the
64      *              encoded bitmap data from the stream.
65      *  @return A new SkPicture representing the serialized data, or NULL if the stream is
66      *          invalid.
67      */
68     static SkPicture* CreateFromStream(SkStream*,
69                                        InstallPixelRefProc proc = &SkImageDecoder::DecodeMemory);
70 
71     virtual ~SkPicture();
72 
73     /**
74      *  Swap the contents of the two pictures. Guaranteed to succeed.
75      */
76     void swap(SkPicture& other);
77 
78     /**
79      *  Creates a thread-safe clone of the picture that is ready for playback.
80      */
81     SkPicture* clone() const;
82 
83     /**
84      * Creates multiple thread-safe clones of this picture that are ready for
85      * playback. The resulting clones are stored in the provided array of
86      * SkPictures.
87      */
88     void clone(SkPicture* pictures, int count) const;
89 
90     enum RecordingFlags {
91         /*  This flag specifies that when clipPath() is called, the path will
92             be faithfully recorded, but the recording canvas' current clip will
93             only see the path's bounds. This speeds up the recording process
94             without compromising the fidelity of the playback. The only side-
95             effect for recording is that calling getTotalClip() or related
96             clip-query calls will reflect the path's bounds, not the actual
97             path.
98          */
99         kUsePathBoundsForClip_RecordingFlag = 0x01,
100         /*  This flag causes the picture to compute bounding boxes and build
101             up a spatial hierarchy (currently an R-Tree), plus a tree of Canvas'
102             usually stack-based clip/etc state. This requires an increase in
103             recording time (often ~2x; likely more for very complex pictures),
104             but allows us to perform much faster culling at playback time, and
105             completely avoid some unnecessary clips and other operations. This
106             is ideal for tiled rendering, or any other situation where you're
107             drawing a fraction of a large scene into a smaller viewport.
108 
109             In most cases the record cost is offset by the playback improvement
110             after a frame or two of tiled rendering (and complex pictures that
111             induce the worst record times will generally get the largest
112             speedups at playback time).
113 
114             Note: Currently this is not serializable, the bounding data will be
115             discarded if you serialize into a stream and then deserialize.
116         */
117         kOptimizeForClippedPlayback_RecordingFlag = 0x02,
118         /*
119             This flag disables all the picture recording optimizations (i.e.,
120             those in SkPictureRecord). It is mainly intended for testing the
121             existing optimizations (i.e., to actually have the pattern
122             appear in an .skp we have to disable the optimization). This
123             option doesn't affect the optimizations controlled by
124             'kOptimizeForClippedPlayback_RecordingFlag'.
125          */
126         kDisableRecordOptimizations_RecordingFlag = 0x04
127     };
128 
129     /** Returns the canvas that records the drawing commands.
130         @param width the base width for the picture, as if the recording
131                      canvas' bitmap had this width.
132         @param height the base width for the picture, as if the recording
133                      canvas' bitmap had this height.
134         @param recordFlags optional flags that control recording.
135         @return the picture canvas.
136     */
137     SkCanvas* beginRecording(int width, int height, uint32_t recordFlags = 0);
138 
139     /** Returns the recording canvas if one is active, or NULL if recording is
140         not active. This does not alter the refcnt on the canvas (if present).
141     */
142     SkCanvas* getRecordingCanvas() const;
143     /** Signal that the caller is done recording. This invalidates the canvas
144         returned by beginRecording/getRecordingCanvas, and prepares the picture
145         for drawing. Note: this happens implicitly the first time the picture
146         is drawn.
147     */
148     void endRecording();
149 
150     /** Replays the drawing commands on the specified canvas. This internally
151         calls endRecording() if that has not already been called.
152         @param canvas the canvas receiving the drawing commands.
153     */
154     void draw(SkCanvas* canvas, SkDrawPictureCallback* = NULL);
155 
156     /** Return the width of the picture's recording canvas. This
157         value reflects what was passed to setSize(), and does not necessarily
158         reflect the bounds of what has been recorded into the picture.
159         @return the width of the picture's recording canvas
160     */
width()161     int width() const { return fWidth; }
162 
163     /** Return the height of the picture's recording canvas. This
164         value reflects what was passed to setSize(), and does not necessarily
165         reflect the bounds of what has been recorded into the picture.
166         @return the height of the picture's recording canvas
167     */
height()168     int height() const { return fHeight; }
169 
170     /**
171      *  Function to encode an SkBitmap to an SkData. A function with this
172      *  signature can be passed to serialize() and SkOrderedWriteBuffer.
173      *  Returning NULL will tell the SkOrderedWriteBuffer to use
174      *  SkBitmap::flatten() to store the bitmap.
175      *  @param pixelRefOffset Output parameter, telling the deserializer what
176      *      offset in the bm's pixelRef corresponds to the encoded data.
177      *  @return SkData If non-NULL, holds encoded data representing the passed
178      *      in bitmap. The caller is responsible for calling unref().
179      */
180     typedef SkData* (*EncodeBitmap)(size_t* pixelRefOffset, const SkBitmap& bm);
181 
182     /**
183      *  Serialize to a stream. If non NULL, encoder will be used to encode
184      *  any bitmaps in the picture.
185      *  encoder will never be called with a NULL pixelRefOffset.
186      */
187     void serialize(SkWStream*, EncodeBitmap encoder = NULL) const;
188 
189     /**
190      * Returns true if any bitmaps may be produced when this SkPicture
191      * is replayed.
192      * Returns false if called while still recording.
193      */
194     bool willPlayBackBitmaps() const;
195 
196 #ifdef SK_BUILD_FOR_ANDROID
197     /** Signals that the caller is prematurely done replaying the drawing
198         commands. This can be called from a canvas virtual while the picture
199         is drawing. Has no effect if the picture is not drawing.
200         @deprecated preserving for legacy purposes
201     */
202     void abortPlayback();
203 #endif
204 
205 protected:
206     // V2 : adds SkPixelRef's generation ID.
207     // V3 : PictInfo tag at beginning, and EOF tag at the end
208     // V4 : move SkPictInfo to be the header
209     // V5 : don't read/write FunctionPtr on cross-process (we can detect that)
210     // V6 : added serialization of SkPath's bounds (and packed its flags tighter)
211     // V7 : changed drawBitmapRect(IRect) to drawBitmapRectToRect(Rect)
212     // V8 : Add an option for encoding bitmaps
213     // V9 : Allow the reader and writer of an SKP disagree on whether to support
214     //      SK_SUPPORT_HINTING_SCALE_FACTOR
215     // V10: add drawRRect, drawOval, clipRRect
216     // V11: modify how readBitmap and writeBitmap store their info.
217     // V12: add conics to SkPath, use new SkPathRef flattening
218     // V13: add flag to drawBitmapRectToRect
219     //      parameterize blurs by sigma rather than radius
220     // V14: Add flags word to PathRef serialization
221     // V15: Remove A1 bitmpa config (and renumber remaining configs)
222     // V16: Move SkPath's isOval flag to SkPathRef
223     // V17: SkPixelRef now writes SkImageInfo
224 #ifndef DELETE_THIS_CODE_WHEN_SKPS_ARE_REBUILT_AT_V16_AND_ALL_OTHER_INSTANCES_TOO
225     static const uint32_t PRIOR_PICTURE_VERSION = 15;  // TODO: remove when .skps regenerated
226 #endif
227     static const uint32_t PICTURE_VERSION = 17;
228 
229     // fPlayback, fRecord, fWidth & fHeight are protected to allow derived classes to
230     // install their own SkPicturePlayback-derived players,SkPictureRecord-derived
231     // recorders and set the picture size
232     SkPicturePlayback* fPlayback;
233     SkPictureRecord* fRecord;
234     int fWidth, fHeight;
235 
236     // Create a new SkPicture from an existing SkPicturePlayback. Ref count of
237     // playback is unchanged.
238     SkPicture(SkPicturePlayback*, int width, int height);
239 
240     // For testing. Derived classes may instantiate an alternate
241     // SkBBoxHierarchy implementation
242     virtual SkBBoxHierarchy* createBBoxHierarchy() const;
243 
244     // Return true if the SkStream represents a serialized picture, and fills out
245     // SkPictInfo. After this function returns, the SkStream is not rewound; it
246     // will be ready to be parsed to create an SkPicturePlayback.
247     // If false is returned, SkPictInfo is unmodified.
248     static bool StreamIsSKP(SkStream*, SkPictInfo*);
249 private:
250     friend class SkFlatPicture;
251     friend class SkPicturePlayback;
252 
253     typedef SkRefCnt INHERITED;
254 };
255 
256 /**
257  *  Subclasses of this can be passed to canvas.drawPicture. During the drawing
258  *  of the picture, this callback will periodically be invoked. If its
259  *  abortDrawing() returns true, then picture playback will be interrupted.
260  *
261  *  The resulting drawing is undefined, as there is no guarantee how often the
262  *  callback will be invoked. If the abort happens inside some level of nested
263  *  calls to save(), restore will automatically be called to return the state
264  *  to the same level it was before the drawPicture call was made.
265  */
266 class SK_API SkDrawPictureCallback {
267 public:
SkDrawPictureCallback()268     SkDrawPictureCallback() {}
~SkDrawPictureCallback()269     virtual ~SkDrawPictureCallback() {}
270 
271     virtual bool abortDrawing() = 0;
272 };
273 
274 #endif
275