chromium/cc/tiles/image_decode_cache.h

// Copyright 2015 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CC_TILES_IMAGE_DECODE_CACHE_H_
#define CC_TILES_IMAGE_DECODE_CACHE_H_

#include <atomic>

#include "base/memory/ref_counted.h"
#include "base/notreached.h"
#include "cc/base/devtools_instrumentation.h"
#include "cc/cc_export.h"
#include "cc/paint/decoded_draw_image.h"
#include "cc/paint/draw_image.h"
#include "cc/raster/tile_task.h"
#include "cc/tiles/image_decode_cache_utils.h"
#include "cc/tiles/tile_priority.h"

namespace cc {

// ImageDecodeCache is responsible for generating decode tasks, decoding
// images, storing images in cache, and being able to return the decoded images
// when requested.

// ImageDecodeCache is responsible for the following things:
// 1. Given a DrawImage, it can return an TileTask which when run will
//    decode and cache the resulting image. If the image does not need a task to
//    be decoded, then nullptr will be returned. The return value of the
//    function indicates whether the image was or is going to be locked, so an
//    unlock will be required.
// 2. Given a cache key and a DrawImage, it can decode the image and store it in
//    the cache. Note that it is important that this function is only accessed
//    via an image decode task.
// 3. Given a DrawImage, it can return a DecodedDrawImage, which represented the
//    decoded version of the image. Note that if the image is not in the cache
//    and it needs to be scaled/decoded, then this decode will happen as part of
//    getting the image. As such, this should only be accessed from a raster
//    thread.
class CC_EXPORT ImageDecodeCache { … };

}  // namespace cc

#endif  // CC_TILES_IMAGE_DECODE_CACHE_H_