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// Copyright 2015 The Chromium Authors. All rights reserved.
// 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_CONTROLLER_H_
#define CC_TILES_IMAGE_DECODE_CONTROLLER_H_
#include "base/memory/ref_counted.h"
#include "cc/playback/decoded_draw_image.h"
#include "cc/playback/draw_image.h"
namespace cc {
class ImageDecodeTask;
// ImageDecodeController is responsible for generating decode tasks, decoding
// images, storing images in cache, and being able to return the decoded images
// when requested.
// ImageDecodeController is responsible for the following things:
// 1. Given a DrawImage, it can return an ImageDecodeTask 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 ImageDecodeController {
public:
virtual ~ImageDecodeController() {}
// Fill in an ImageDecodeTask which will decode the given image when run. In
// case the image is already cached, fills in nullptr. Returns true if the
// image needs to be unreffed when the caller is finished with it.
//
// This is called by the tile manager (on the compositor thread) when creating
// a raster task.
virtual bool GetTaskForImageAndRef(const DrawImage& image,
uint64_t prepare_tiles_id,
scoped_refptr<ImageDecodeTask>* task) = 0;
// Unrefs an image. When the tile is finished, this should be called for every
// GetTaskForImageAndRef call that returned true.
virtual void UnrefImage(const DrawImage& image) = 0;
// Returns a decoded draw image. This may cause a decode if the image was not
// predecoded.
//
// This is called by a raster task (on a worker thread) when an image is
// required.
virtual DecodedDrawImage GetDecodedImageForDraw(const DrawImage& image) = 0;
// Unrefs an image. This should be called for every GetDecodedImageForDraw
// when the draw with the image is finished.
virtual void DrawWithImageFinished(const DrawImage& image,
const DecodedDrawImage& decoded_image) = 0;
// This function informs the controller that now is a good time to clean up
// memory. This is called periodically from the compositor thread.
virtual void ReduceCacheUsage() = 0;
};
} // namespace cc
#endif // CC_TILES_IMAGE_DECODE_CONTROLLER_H_
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