Speed up custom wallpaper switching time and wallpaper manager code refactor

chrome/browser/chromeos/login/wallpaper_loader.cc

+// Copyright (c) 2012 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/chromeos/login/wallpaper_loader.h"
+
+#include "base/bind.h"
+#include "base/file_path.h"
+#include "base/file_util.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/message_loop.h"
+#include "content/public/browser/browser_thread.h"
+#include "skia/ext/image_operations.h"
+#include "third_party/skia/include/core/SkBitmap.h"
+#include "ui/gfx/codec/png_codec.h"
+#include "ui/gfx/skbitmap_operations.h"
+
+using content::BrowserThread;
+
+namespace chromeos {
+
+WallpaperLoader::WallpaperInfo::WallpaperInfo(bool save_raw_image,
+                                              const std::string& save_to_path,
+                                              const LoadedCallback& loaded_cb)
+    : save_raw_image(save_raw_image),
+      save_to_path(save_to_path),
+      loaded_cb(loaded_cb) {
+}
+
+WallpaperLoader::WallpaperInfo::~WallpaperInfo() {
+}
+
+WallpaperLoader::WallpaperLoader()
+    : target_message_loop_(NULL) {
+}
+
+WallpaperLoader::~WallpaperLoader() {
+}
+
+void WallpaperLoader::Start(const std::string& filepath,
+                            bool save_raw_image,
+                            const std::string& save_to_path,
+                            const LoadedCallback& loaded_cb) {
+  target_message_loop_ = MessageLoop::current();
+
+  WallpaperInfo info(save_raw_image, save_to_path, loaded_cb);
+
+  BrowserThread::PostTask(
+      BrowserThread::FILE, FROM_HERE,
+      base::Bind(&WallpaperLoader::LoadImage, this, filepath, info));
+}
+
+void WallpaperLoader::LoadImage(const std::string& filepath,
+                                const WallpaperInfo& wallpaper_info) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
+
+  std::string image_data;
+  file_util::ReadFileToString(FilePath(filepath), &image_data);
+
+  scoped_refptr<ImageDecoder> image_decoder =
+      new ImageDecoder(this, image_data);
+  wallpaper_info_map_.insert(std::make_pair(image_decoder.get(),
+                                            wallpaper_info));
+  image_decoder->Start();
+}
+
+void WallpaperLoader::OnImageDecoded(const ImageDecoder* decoder,
+                                     const SkBitmap& decoded_image) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
+
+  WallpaperInfoMap::iterator wallpaper_info_it =
+      wallpaper_info_map_.find(decoder);
+  if (wallpaper_info_it == wallpaper_info_map_.end()) {
+    NOTREACHED();
+    return;
+  }
+
+  const WallpaperInfo& info = wallpaper_info_it->second;
+
+  if (info.save_raw_image) {
+    std::vector<unsigned char> image_data = decoder->get_image_data();
+    int write_bytes = file_util::WriteFile(FilePath(info.save_to_path),
+        reinterpret_cast<char*>(&*image_data.begin()),
+        image_data.size());
+    DCHECK(write_bytes == static_cast<int>(image_data.size()));
+  }
+
+  const LoadedCallback& loaded_cb = info.loaded_cb;
+
+  target_message_loop_->PostTask(
+      FROM_HERE,
+      base::Bind(loaded_cb, decoded_image));
+
+  wallpaper_info_map_.erase(wallpaper_info_it);
+}
+
+void WallpaperLoader::OnDecodeImageFailed(const ImageDecoder* decoder) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
+  wallpaper_info_map_.erase(decoder);
+}
+
+}  // namespace chromeos