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1 /* | |
2 * Copyright 2013 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 SkCanvasStateUtils_DEFINED | |
9 #define SkCanvasStateUtils_DEFINED | |
10 | |
11 #include "SkCanvas.h" | |
12 | |
13 struct SkCanvasState; | |
14 | |
15 /** | |
16 * A set of functions that are useful for copying an SkCanvas across a library | |
17 * boundary where the Skia libraries on either side of the boundary may not be | |
18 * version identical. The expected usage is outline below... | |
19 * | |
20 * Lib Boundary | |
21 * CaptureCanvasState(...) ||| | |
22 * SkCanvas --> SkCanvasState ||| | |
23 * ||| CreateFromCanvasState(...) | |
24 * ||| SkCanvasState --> SkCanvas` | |
25 * ||| Draw into SkCanvas` | |
26 * ||| Unref SkCanvas` | |
27 * ReleaseCanvasState(...) ||| | |
28 * | |
29 */ | |
30 namespace SkCanvasStateUtils { | |
31 /** | |
32 * Captures the current state of the canvas into an opaque ptr that is safe | |
33 * to pass between different instances of Skia (which may or may not be the | |
34 * same version). The function will return NULL in the event that one of the | |
35 * following conditions are true. | |
36 * 1) the canvas device type is not supported (currently only raster is sup
ported) | |
37 * 2) the canvas clip type is not supported (currently only non-AA clips ar
e supported) | |
38 * | |
39 * It is recommended that the original canvas also not be used until all | |
40 * canvases that have been created using its captured state have been derefe
renced. | |
41 * | |
42 * Finally, it is important to note that any draw filters attached to the | |
43 * canvas are NOT currently captured. | |
44 * | |
45 * @param canvas The canvas you wish to capture the current state of. | |
46 * @return NULL or an opaque ptr that can be passed to CreateFromCanvasState | |
47 * to reconstruct the canvas. The caller is responsible for calling | |
48 * ReleaseCanvasState to free the memory associated with this state. | |
49 */ | |
50 SK_API SkCanvasState* CaptureCanvasState(SkCanvas* canvas); | |
51 | |
52 /** | |
53 * Create a new SkCanvas from the captured state of another SkCanvas. The | |
54 * function will return NULL in the event that one of the | |
55 * following conditions are true. | |
56 * 1) the captured state is in an unrecognized format | |
57 * 2) the captured canvas device type is not supported | |
58 * | |
59 * @param canvas The canvas you wish to capture the current state of. | |
60 * @return NULL or an SkCanvas* whose devices and matrix/clip state are | |
61 * identical to the captured canvas. The caller is responsible for | |
62 * calling unref on the SkCanvas. | |
63 */ | |
64 SK_API SkCanvas* CreateFromCanvasState(const SkCanvasState* state); | |
65 | |
66 /** | |
67 * Free the memory associated with the captured canvas state. The state | |
68 * should not be released until all SkCanvas objects created using that | |
69 * state have been dereferenced. | |
70 * | |
71 * @param state The captured state you wish to dispose of. | |
72 */ | |
73 SK_API void ReleaseCanvasState(SkCanvasState* state); | |
74 }; | |
75 | |
76 #endif | |
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