2 * Copyright 2013 Google Inc.
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
8 #ifndef SkCanvasStateUtils_DEFINED
9 #define SkCanvasStateUtils_DEFINED
16 * A set of functions that are useful for copying the state of an SkCanvas
17 * across a library boundary where the Skia library on the other side of the
18 * boundary may be newer. The expected usage is outline below...
21 * CaptureCanvasState(...) |||
22 * SkCanvas --> SkCanvasState |||
23 * ||| CreateFromCanvasState(...)
24 * ||| SkCanvasState --> SkCanvas`
25 * ||| Draw into SkCanvas`
27 * ReleaseCanvasState(...) |||
30 namespace SkCanvasStateUtils {
32 * Captures the current state of the canvas into an opaque ptr that is safe
33 * to pass to a different instance of Skia (which may be the same version,
34 * or may be newer). 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 supported)
37 * 2) the canvas clip type is not supported (currently only non-AA clips are supported)
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 dereferenced.
42 * Finally, it is important to note that any draw filters attached to the
43 * canvas are NOT currently captured.
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.
50 SK_API SkCanvasState* CaptureCanvasState(SkCanvas* canvas);
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
59 * @param state Opaque object created by CaptureCanvasState.
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.
64 SK_API SkCanvas* CreateFromCanvasState(const SkCanvasState* state);
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. Must be called from the same library
70 * instance that created the state via CaptureCanvasState.
72 * @param state The captured state you wish to dispose of.
74 SK_API void ReleaseCanvasState(SkCanvasState* state);