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/*
* Copyright 2013 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SkCanvasStateUtils_DEFINED
#define SkCanvasStateUtils_DEFINED
#include "SkCanvas.h"
class SkCanvasState;
/**
* A set of functions that are useful for copying the state of an SkCanvas
* across a library boundary where the Skia library on the other side of the
* boundary may be newer. The expected usage is outline below...
*
* Lib Boundary
* CaptureCanvasState(...) |||
* SkCanvas --> SkCanvasState |||
* ||| CreateFromCanvasState(...)
* ||| SkCanvasState --> SkCanvas`
* ||| Draw into SkCanvas`
* ||| Unref SkCanvas`
* ReleaseCanvasState(...) |||
*
*/
class SK_API SkCanvasStateUtils {
public:
/**
* Captures the current state of the canvas into an opaque ptr that is safe
* to pass to a different instance of Skia (which may be the same version,
* or may be newer). The function will return NULL in the event that one of the
* following conditions are true.
* 1) the canvas device type is not supported (currently only raster is supported)
* 2) the canvas clip type is not supported (currently only non-AA clips are supported)
*
* It is recommended that the original canvas also not be used until all
* canvases that have been created using its captured state have been dereferenced.
*
* Finally, it is important to note that any draw filters attached to the
* canvas are NOT currently captured.
*
* @param canvas The canvas you wish to capture the current state of.
* @return NULL or an opaque ptr that can be passed to CreateFromCanvasState
* to reconstruct the canvas. The caller is responsible for calling
* ReleaseCanvasState to free the memory associated with this state.
*/
static SkCanvasState* CaptureCanvasState(SkCanvas* canvas);
/**
* Create a new SkCanvas from the captured state of another SkCanvas. The
* function will return NULL in the event that one of the
* following conditions are true.
* 1) the captured state is in an unrecognized format
* 2) the captured canvas device type is not supported
*
* @param state Opaque object created by CaptureCanvasState.
* @return NULL or an SkCanvas* whose devices and matrix/clip state are
* identical to the captured canvas. The caller is responsible for
* calling unref on the SkCanvas.
*/
static std::unique_ptr<SkCanvas> MakeFromCanvasState(const SkCanvasState* state);
/**
* Free the memory associated with the captured canvas state. The state
* should not be released until all SkCanvas objects created using that
* state have been dereferenced. Must be called from the same library
* instance that created the state via CaptureCanvasState.
*
* @param state The captured state you wish to dispose of.
*/
static void ReleaseCanvasState(SkCanvasState* state);
};
#endif
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