Make painting app list items more efficient by caching the labels.

BUG=170069


Review URL: https://chromiumcodereview.appspot.com/12771021

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@187822 0039d316-1c4b-4281-b951-d872f2087c98

5 files changed, 84 insertions, 2 deletions

diff --git a/ui/app_list/app_list.gyp b/ui/app_list/app_list.gyp
index 144b878..5827324 100644
--- a/ui/app_list/app_list.gyp
+++ b/ui/app_list/app_list.gyp
@@ -67,6 +67,8 @@
         'views/app_list_view.h',
         'views/apps_grid_view.cc',
         'views/apps_grid_view.h',
+        'views/cached_label.cc',
+        'views/cached_label.h',
         'views/contents_view.cc',
         'views/contents_view.h',
         'views/page_switcher.cc',
diff --git a/ui/app_list/views/app_list_item_view.cc b/ui/app_list/views/app_list_item_view.cc
index dcf023a..640aa57 100644
--- a/ui/app_list/views/app_list_item_view.cc
+++ b/ui/app_list/views/app_list_item_view.cc
@@ -10,6 +10,7 @@
 #include "grit/ui_resources.h"
 #include "ui/app_list/app_list_item_model.h"
 #include "ui/app_list/views/apps_grid_view.h"
+#include "ui/app_list/views/cached_label.h"
 #include "ui/base/accessibility/accessible_view_state.h"
 #include "ui/base/animation/throb_animation.h"
 #include "ui/base/resource/resource_bundle.h"
@@ -65,7 +66,7 @@ AppListItemView::AppListItemView(AppsGridView* apps_grid_view,
       model_(model),
       apps_grid_view_(apps_grid_view),
       icon_(new views::ImageView),
-      title_(new views::Label),
+      title_(new CachedLabel),
       ui_state_(UI_STATE_NORMAL),
       touch_dragging_(false) {
   icon_->set_interactive(false);
@@ -77,6 +78,7 @@ AppListItemView::AppListItemView(AppsGridView* apps_grid_view,
   title_->SetFont(rb.GetFont(ui::ResourceBundle::SmallBoldFont));
   title_->SetHorizontalAlignment(gfx::ALIGN_LEFT);
   title_->SetVisible(!model_->is_installing());
+  title_->Invalidate();
 
   const gfx::ShadowValue kIconShadows[] = {
     gfx::ShadowValue(gfx::Point(0, 2), 2, SkColorSetARGB(0x24, 0, 0, 0)),
@@ -176,6 +178,7 @@ void AppListItemView::ItemIconChanged() {
 
 void AppListItemView::ItemTitleChanged() {
   title_->SetText(UTF8ToUTF16(model_->title()));
+  title_->Invalidate();
 }
 
 void AppListItemView::ItemHighlightedChanged() {
@@ -296,6 +299,7 @@ void AppListItemView::StateChanged() {
     model_->SetHighlighted(false);
     title_->SetEnabledColor(kTitleColor);
   }
+  title_->Invalidate();
 }
 
 bool AppListItemView::ShouldEnterPushedState(const ui::Event& event) {
diff --git a/ui/app_list/views/app_list_item_view.h b/ui/app_list/views/app_list_item_view.h
index a037de2..c2f9d05 100644
--- a/ui/app_list/views/app_list_item_view.h
+++ b/ui/app_list/views/app_list_item_view.h
@@ -28,6 +28,7 @@ namespace app_list {
 
 class AppListItemModel;
 class AppsGridView;
+class CachedLabel;
 
 class APP_LIST_EXPORT AppListItemView : public views::CustomButton,
                                         public views::ContextMenuController,
@@ -95,7 +96,7 @@ class APP_LIST_EXPORT AppListItemView : public views::CustomButton,
 
   AppsGridView* apps_grid_view_;  // Owned by views hierarchy.
   views::ImageView* icon_;  // Owned by views hierarchy.
-  views::Label* title_;  // Owned by views hierarchy.
+  CachedLabel* title_;  // Owned by views hierarchy.
 
   scoped_ptr<views::MenuRunner> context_menu_runner_;
 
diff --git a/ui/app_list/views/cached_label.cc b/ui/app_list/views/cached_label.cc
new file mode 100644
index 0000000..60f731e
--- /dev/null
+++ b/ui/app_list/views/cached_label.cc
@@ -0,0 +1,34 @@
+// Copyright 2013 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 "ui/app_list/views/cached_label.h"
+
+#include "base/utf_string_conversions.h"
+#include "ui/base/resource/resource_bundle.h"
+#include "ui/gfx/canvas.h"
+
+namespace app_list {
+
+CachedLabel::CachedLabel()
+    : needs_repaint_(true) {
+}
+
+void CachedLabel::PaintToBackingImage() {
+  gfx::Canvas canvas(size(), ui::SCALE_FACTOR_100P, false /* is_opaque */);
+  canvas.FillRect(GetLocalBounds(), SkColorSetARGB(0, 0, 0, 0),
+                  SkXfermode::kSrc_Mode);
+  Label::OnPaint(&canvas);
+  image_ = gfx::ImageSkia(canvas.ExtractImageRep());
+}
+
+#if defined(OS_WIN)
+void CachedLabel::OnPaint(gfx::Canvas* canvas) {
+  if (needs_repaint_)
+    PaintToBackingImage();
+  needs_repaint_ = false;
+  canvas->DrawImageInt(image_, 0, 0);
+}
+#endif
+
+}  // namespace app_list
diff --git a/ui/app_list/views/cached_label.h b/ui/app_list/views/cached_label.h
new file mode 100644
index 0000000..a5a497a
--- /dev/null
+++ b/ui/app_list/views/cached_label.h
@@ -0,0 +1,41 @@
+// Copyright 2013 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 UI_APP_LIST_VIEWS_CACHED_LABEL_H_
+#define UI_APP_LIST_VIEWS_CACHED_LABEL_H_
+
+#include "ui/gfx/image/image_skia.h"
+#include "ui/views/controls/label.h"
+#include "ui/views/view.h"
+
+namespace gfx {
+class Canvas;
+}
+
+namespace app_list {
+
+// Subclass of views::Label that caches the rendered text in an ImageSkia.
+class CachedLabel : public views::Label {
+ public:
+  CachedLabel();
+
+  // Have the next call to OnPaint() update the backing image.
+  void Invalidate() { needs_repaint_ = true; }
+
+#if defined(OS_WIN)
+  // views::View overrides.
+  virtual void OnPaint(gfx::Canvas* canvas) OVERRIDE;
+#endif
+
+ private:
+  // Calls the base label's OnPaint() to paint into a backing image.
+  void PaintToBackingImage();
+
+  bool needs_repaint_;
+  gfx::ImageSkia image_;
+};
+
+}  // namespace app_list
+
+#endif  // UI_APP_LIST_VIEWS_CACHED_LABEL_H_