chromium/third_party/skia/include/core/SkRasterHandleAllocator.h

/*
 * Copyright 2016 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef SkRasterHandleAllocator_DEFINED
#define SkRasterHandleAllocator_DEFINED

#include "include/core/SkImageInfo.h"

class SkBitmap;
class SkCanvas;
class SkMatrix;
class SkSurfaceProps;

/**
 *  If a client wants to control the allocation of raster layers in a canvas, it should subclass
 *  SkRasterHandleAllocator. This allocator performs two tasks:
 *      1. controls how the memory for the pixels is allocated
 *      2. associates a "handle" to a private object that can track the matrix/clip of the SkCanvas
 *
 *  This example allocates a canvas, and defers to the allocator to create the base layer.
 *
 *      std::unique_ptr<SkCanvas> canvas = SkRasterHandleAllocator::MakeCanvas(
 *              SkImageInfo::Make(...),
 *              std::make_unique<MySubclassRasterHandleAllocator>(...),
 *              nullptr);
 *
 *  If you have already allocated the base layer (and its handle, release-proc etc.) then you
 *  can pass those in using the last parameter to MakeCanvas().
 *
 *  Regardless of how the base layer is allocated, each time canvas->saveLayer() is called,
 *  your allocator's allocHandle() will be called.
 */
class SK_API SkRasterHandleAllocator { … };

#endif