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 class SkCanvasState; 14 15 /** 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... 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 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) 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 dereferenced. 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 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. 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. Must be called from the same library 70 * instance that created the state via CaptureCanvasState. 71 * 72 * @param state The captured state you wish to dispose of. 73 */ 74 SK_API void ReleaseCanvasState(SkCanvasState* state); 75 }; 76 77 #endif 78
