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// Copyright (c) 2009 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 CHROME_BROWSER_IMAGE_LOADING_TRACKER_H_
#define CHROME_BROWSER_IMAGE_LOADING_TRACKER_H_
#include "base/ref_counted.h"
class FilePath;
class SkBitmap;
// The views need to load their icons asynchronously but might be deleted before
// the images have loaded. This class stays alive while the request is in
// progress (manages its own lifetime) and keeps track of whether the view still
// cares about the icon loading.
class ImageLoadingTracker
: public base::RefCountedThreadSafe<ImageLoadingTracker> {
public:
class Observer {
public:
// Will be called when the image with the given index has loaded.
// The |image| is owned by the tracker, so the observer should make a copy
// if they need to access it after this call.
virtual void OnImageLoaded(SkBitmap* image, size_t index) = 0;
};
ImageLoadingTracker(Observer* observer, size_t image_count)
: observer_(observer), image_count_(image_count), posted_count_(0) {
AddRef(); // We hold on to a reference to ourself to make sure we don't
// get deleted until we get a response from image loading (see
// ImageLoadingDone).
}
~ImageLoadingTracker() {}
// If there are remaining images to be loaded, the observing object should
// call this method on its destruction, so that the tracker will not attempt
// to make any more callbacks to it.
void StopTrackingImageLoad() {
observer_ = NULL;
}
// Specify path of image to load. This method must be called a number of
// times equal to the |image_count| arugment to the constructor. Calling it
// any more or less than that is an error.
void PostLoadImageTask(FilePath path);
private:
class LoadImageTask;
// When an image has finished loaded and scaled on the file thread, it is
// posted back to this method on the original thread. This method then calls
// the observer's OnImageLoaded and deletes the ImageLoadingTracker if it was
// the last image in the list.
// |image| may be null if the file failed to decode.
void OnImageLoaded(SkBitmap* image, size_t index);
// The view that is waiting for the image to load.
Observer* observer_;
// The number of images this ImageTracker should keep track of. This is
// decremented as each image finishes loading, and the tracker will delete
// itself when it reaches zero.
size_t image_count_;
// The number of tasks that have been posted so far.
size_t posted_count_;
DISALLOW_COPY_AND_ASSIGN(ImageLoadingTracker);
};
#endif // CHROME_BROWSER_IMAGE_LOADING_TRACKER_H_
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