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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.
#include "chrome/browser/extensions/image_loading_tracker.h"
#include "base/file_util.h"
#include "base/gfx/size.h"
#include "base/logging.h"
#include "base/message_loop.h"
#include "base/scoped_ptr.h"
#include "base/task.h"
#include "base/thread.h"
#include "chrome/browser/chrome_thread.h"
#include "chrome/common/extensions/extension_resource.h"
#include "skia/ext/image_operations.h"
#include "third_party/skia/include/core/SkBitmap.h"
#include "webkit/glue/image_decoder.h"
////////////////////////////////////////////////////////////////////////////////
// ImageLoadingTracker::LoadImageTask
// The LoadImageTask is for asynchronously loading the image on the file thread.
// If the image is successfully loaded and decoded it will report back on the
// calling thread to let the caller know the image is done loading.
class ImageLoadingTracker::LoadImageTask : public Task {
public:
// Constructor for the LoadImageTask class. |tracker| is the object that
// we use to communicate back to the entity that wants the image after we
// decode it. |path| is the path to load the image from. |max_size| is the
// maximum size for the loaded image. It will be resized to fit this if
// larger. |index| is an identifier for the image that we pass back to the
// caller.
LoadImageTask(ImageLoadingTracker* tracker,
const ExtensionResource& resource,
const gfx::Size& max_size,
size_t index)
: tracker_(tracker),
resource_(resource),
max_size_(max_size),
index_(index) {
CHECK(ChromeThread::GetCurrentThreadIdentifier(&callback_thread_id_));
}
void ReportBack(SkBitmap* image) {
ChromeThread::PostTask(
callback_thread_id_, FROM_HERE,
NewRunnableMethod(
tracker_, &ImageLoadingTracker::OnImageLoaded, image, index_));
}
virtual void Run() {
// Read the file from disk.
std::string file_contents;
FilePath path = resource_.GetFilePath();
if (path.empty() || !file_util::ReadFileToString(path, &file_contents)) {
ReportBack(NULL);
return;
}
// Decode the image using WebKit's image decoder.
const unsigned char* data =
reinterpret_cast<const unsigned char*>(file_contents.data());
webkit_glue::ImageDecoder decoder;
scoped_ptr<SkBitmap> decoded(new SkBitmap());
*decoded = decoder.Decode(data, file_contents.length());
if (decoded->empty()) {
ReportBack(NULL);
return; // Unable to decode.
}
if (decoded->width() > max_size_.width() ||
decoded->height() > max_size_.height()) {
// The bitmap is too big, re-sample.
*decoded = skia::ImageOperations::Resize(
*decoded, skia::ImageOperations::RESIZE_LANCZOS3,
max_size_.width(), max_size_.height());
}
ReportBack(decoded.release());
}
private:
// The thread that we need to call back on to report that we are done.
ChromeThread::ID callback_thread_id_;
// The object that is waiting for us to respond back.
ImageLoadingTracker* tracker_;
// The image resource to load asynchronously.
ExtensionResource resource_;
// The max size for the loaded image.
gfx::Size max_size_;
// The index of the icon being loaded.
size_t index_;
};
////////////////////////////////////////////////////////////////////////////////
// ImageLoadingTracker
void ImageLoadingTracker::PostLoadImageTask(const ExtensionResource& resource,
const gfx::Size& max_size) {
ChromeThread::PostTask(
ChromeThread::FILE, FROM_HERE,
new LoadImageTask(this, resource, max_size, posted_count_++));
}
void ImageLoadingTracker::OnImageLoaded(SkBitmap* image, size_t index) {
if (observer_)
observer_->OnImageLoaded(image, index);
if (image)
delete image;
if (--image_count_ == 0)
Release(); // We are no longer needed.
}
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