Reland 129925 - ash: Icon cache for app list to save shadow generation time.

- Add an IconCache that stores processed (resized and shadow-generated) image,
  keyed by source image + desired size;
- The cache is created with AppList controller and destroyed when controller is
  gone;
- Controller marks all entries in cache unused before showing the UI and purges
  all unused entry after dismissing UI;
- In item view, try cache first to get processed image before scheduling job,
  and update cache when background processing comes back;

BUG=120961
TEST=Verify fix for issue 120961.

Review URL: http://codereview.chromium.org/9934006

TBR=sky@chromium.org

Review URL: https://chromiumcodereview.appspot.com/9968024

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@130035 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 90 insertions, 0 deletions

diff --git a/ash/app_list/icon_cache.cc b/ash/app_list/icon_cache.cc
new file mode 100644
index 0000000..92fdd90
--- /dev/null
+++ b/ash/app_list/icon_cache.cc
@@ -0,0 +1,90 @@
+// 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 "ash/app_list/icon_cache.h"
+
+#include "base/logging.h"
+#include "base/md5.h"
+#include "ui/gfx/size.h"
+
+namespace {
+
+// Gets cache key based on |image| contents and desired |size|.
+std::string GetKey(const SkBitmap& image, const gfx::Size& size) {
+  SkAutoLockPixels image_lock(image);
+  base::MD5Digest digest;
+  MD5Sum(image.getPixels(), image.getSize(), &digest);
+
+  return MD5DigestToBase16(digest) + "." + size.ToString();
+}
+
+}  // namespace
+
+namespace ash {
+
+// static
+IconCache* IconCache::instance_ = NULL;
+
+// static
+void IconCache::CreateInstance() {
+  DCHECK(!instance_);
+  instance_ = new IconCache;
+}
+
+// static
+void IconCache::DeleteInstance() {
+  DCHECK(instance_);
+  delete instance_;
+  instance_ = NULL;
+}
+
+// static
+IconCache* IconCache::GetInstance() {
+  DCHECK(instance_);
+  return instance_;
+}
+
+void IconCache::MarkAllEntryUnused() {
+  for (Cache::iterator i = cache_.begin(); i != cache_.end(); ++i)
+    i->second.used = false;
+}
+
+void IconCache::PurgeAllUnused() {
+  for (Cache::iterator i = cache_.begin(); i != cache_.end();) {
+    Cache::iterator current(i);
+    ++i;
+    if (!current->second.used)
+      cache_.erase(current);
+  }
+}
+
+bool IconCache::Get(const SkBitmap& src,
+                    const gfx::Size& size,
+                    SkBitmap* processed) {
+  Cache::iterator it = cache_.find(GetKey(src, size));
+  if (it == cache_.end())
+    return false;
+
+  it->second.used = true;
+
+  if (processed)
+    *processed = it->second.image;
+  return true;
+}
+
+void IconCache::Put(const SkBitmap& src,
+                    const gfx::Size& size,
+                    const SkBitmap& processed) {
+  const std::string key = GetKey(src, size);
+  cache_[key].image = processed;
+  cache_[key].used = true;
+}
+
+IconCache::IconCache() {
+}
+
+IconCache::~IconCache() {
+}
+
+}  // namespace ash