Implement animation UI for opening/closing an app list folder.

ui/app_list/views/apps_container_view.cc

Index: ui/app_list/views/apps_container_view.cc
diff --git a/ui/app_list/views/apps_container_view.cc b/ui/app_list/views/apps_container_view.cc
index 6b3054d1a4781fa22a20e53bd63e32d7804098d6..6a275558c81dd245672b416051c3794c6671ed1a 100644
--- a/ui/app_list/views/apps_container_view.cc
+++ b/ui/app_list/views/apps_container_view.cc
@@ -10,12 +10,107 @@
 #include "ui/app_list/app_list_folder_item.h"
 #include "ui/app_list/pagination_model.h"
 #include "ui/app_list/views/app_list_folder_view.h"
+#include "ui/app_list/views/app_list_item_view.h"
 #include "ui/app_list/views/app_list_main_view.h"
 #include "ui/app_list/views/apps_grid_view.h"
+#include "ui/compositor/scoped_layer_animation_settings.h"
 #include "ui/events/event.h"
+#include "ui/gfx/image/image_skia_operations.h"
+#include "ui/views/controls/image_view.h"
 
 namespace app_list {
 
+namespace {
+
+// Transitional view used for top item icons animation when opening or closing
+// a folder.
+class TopIconAnimationView : public views::View,
+                             public ui::ImplicitAnimationObserver {
+ public:
+  TopIconAnimationView(const gfx::ImageSkia& icon,
+                       const gfx::Rect& scaled_rect,
+                       bool open_folder)
+      : icon_size_(kPreferredIconDimension, kPreferredIconDimension),
+        icon_(new views::ImageView),
+        scaled_rect_(scaled_rect),
+        open_folder_(open_folder) {
+    DCHECK(!icon.isNull());
+    gfx::ImageSkia resized(gfx::ImageSkiaOperations::CreateResizedImage(
+          icon,
+          skia::ImageOperations::RESIZE_BEST, icon_size_));
+    icon_->SetImage(resized);
+    AddChildView(icon_);
+
+#if defined(USE_AURA)
+    SetPaintToLayer(true);
+    SetFillsBoundsOpaquely(false);
+#endif
+  }
+  virtual ~TopIconAnimationView() {}
+
+  void AddObserver(TopIconAnimationObserver* observer) {
+    observers_.AddObserver(observer);
+  }
+
+  void RemoveObserver(TopIconAnimationObserver* observer) {
+    observers_.RemoveObserver(observer);
+  }
+
+  void TransformView() {
+    // Transform used for scaling down the icon and move it back inside to the
+    // original folder icon.
+    const float kIconTransformScale = 0.33333f;
+    gfx::Transform transform;
+    transform.Translate(scaled_rect_.x() - layer()->bounds().x(),
+                        scaled_rect_.y() - layer()->bounds().y());
+    transform.Scale(kIconTransformScale, kIconTransformScale);
+
+    if (open_folder_) {
+      // Transform to a scaled down icon inside the original folder icon.
+      layer()->SetTransform(transform);
+    }
+
+    // Animate the icon to its target location and scale when opening or
+    // closing a folder.
+    ui::ScopedLayerAnimationSettings settings(layer()->GetAnimator());
+    settings.AddObserver(this);
+    settings.SetTransitionDuration(
+        base::TimeDelta::FromMilliseconds(kFolderTransitionInDurationMs));
+    layer()->SetTransform(open_folder_ ? gfx::Transform() : transform);
+  }
+
+ private:
+  // views::View overrides:
+  virtual gfx::Size GetPreferredSize() OVERRIDE {
+    return icon_size_;
+  }
+
+  virtual void Layout() OVERRIDE {
+    icon_->SetBoundsRect(GetContentsBounds());
+  }
+
+  // ui::ImplicitAnimationObserver overrides:
+  virtual void OnImplicitAnimationsCompleted() OVERRIDE {
+    SetVisible(false);
+    FOR_EACH_OBSERVER(TopIconAnimationObserver,
+                      observers_,
+                      OnTopIconAnimationsComplete(this));
+  }
+
+  gfx::Size icon_size_;
+  views::ImageView* icon_;  // Owned by views hierarchy.
+  // Rect of the scaled down top item icon inside folder icon's ink bubble.
+  gfx::Rect scaled_rect_;
+  // True: opening folder; False: closing folder.
+  bool open_folder_;
+
+  ObserverList<TopIconAnimationObserver> observers_;
+
+  DISALLOW_COPY_AND_ASSIGN(TopIconAnimationView);
+};
+
+}  // namespace
+
 AppsContainerView::AppsContainerView(AppListMainView* app_list_main_view,
                                      PaginationModel* pagination_model,
                                      AppListModel* model,
@@ -46,9 +141,14 @@ AppsContainerView::~AppsContainerView() {
 void AppsContainerView::ShowActiveFolder(AppListFolderItem* folder_item) {
   app_list_folder_view_->SetAppListFolderItem(folder_item);
   SetShowState(SHOW_ACTIVE_FOLDER);
+
+  CreateViewsForFolderTopItemsAnimation(folder_item, true);
 }
 
-void AppsContainerView::ShowApps() {
+void AppsContainerView::ShowApps(AppListFolderItem* folder_item) {
+  CreateViewsForFolderTopItemsAnimation(folder_item, false);
+  // Hide the active folder view until the animation completes.
+  apps_grid_view_->activated_item_view()->SetVisible(false);
   SetShowState(SHOW_APPS);
 }
 
@@ -68,14 +168,14 @@ void AppsContainerView::Layout() {
 
   switch (show_state_) {
     case SHOW_APPS:
-      app_list_folder_view_->SetVisible(false);
+      app_list_folder_view_->ScheduleShowHideAnimation(false);
       apps_grid_view_->SetBoundsRect(rect);
-      apps_grid_view_->SetVisible(true);
+      apps_grid_view_->ScheduleShowHideAnimation(true);
       break;
     case SHOW_ACTIVE_FOLDER:
-      apps_grid_view_->SetVisible(false);
+      apps_grid_view_->ScheduleShowHideAnimation(false);
       app_list_folder_view_->SetBoundsRect(rect);
-      app_list_folder_view_->SetVisible(true);
+      app_list_folder_view_->ScheduleShowHideAnimation(true);
       break;
     default:
       NOTREACHED();
@@ -89,6 +189,31 @@ bool AppsContainerView::OnKeyPressed(const ui::KeyEvent& event) {
     return app_list_folder_view_->OnKeyPressed(event);
 }
 
+void AppsContainerView::OnTopIconAnimationsComplete(views::View* icon_view) {
+  bool animations_done = true;
+  for (size_t i = 0; i < top_icon_views_.size(); ++i) {
+    if (top_icon_views_[i]->visible()) {
+      animations_done = false;
+      break;
+    }
+  }
+
+  if (animations_done) {
+    // Clean up the transitional views using for top item icon animation.
+    for (size_t i = 0; i < top_icon_views_.size(); ++i) {
+      TopIconAnimationView* icon_view =
+          static_cast<TopIconAnimationView*>(top_icon_views_[i]);
+      icon_view->RemoveObserver(this);
+      delete icon_view;
+    }
+    top_icon_views_.clear();
+
+    // Show the folder icon when closing the folder.
+    if (show_state_ == SHOW_APPS && apps_grid_view_->activated_item_view())
+      apps_grid_view_->activated_item_view()->SetVisible(true);
+  }
+}
+
 void AppsContainerView::SetShowState(ShowState show_state) {
   if (show_state_ == show_state)
     return;
@@ -97,4 +222,38 @@ void AppsContainerView::SetShowState(ShowState show_state) {
   Layout();
 }
 
+Rects AppsContainerView::GetTopItemIconBoundsInActiveFolder() {
+  // Get the active folder's icon bounds relative to AppsContainerView.
+  AppListItemView* folder_view = apps_grid_view_->activated_item_view();
+  gfx::Rect to_grid_view = folder_view->ConvertRectToParent(
+      folder_view->GetIconBounds());
+  gfx::Rect to_container = apps_grid_view_->ConvertRectToParent(to_grid_view);
+
+  return AppListFolderItem::GetTopIconsBounds(to_container);
+}
+
+void AppsContainerView::CreateViewsForFolderTopItemsAnimation(
+    AppListFolderItem* active_folder,
+    bool open_folder) {
+  top_icon_views_.clear();
+  std::vector<gfx::Rect> top_items_bounds =
+      GetTopItemIconBoundsInActiveFolder();
+  size_t top_items_count =
+      std::min(kNumFolderTopItems, active_folder->item_list()->item_count());
+  for (size_t i = 0; i < top_items_count; ++i) {
+    TopIconAnimationView* icon_view = new TopIconAnimationView(
+        active_folder->GetTopIcon(i), top_items_bounds[i], open_folder);
+    icon_view->AddObserver(this);
+    top_icon_views_.push_back(icon_view);
+
+    // Add the transitional views into child views, and set its bounds to the
+    // same location of the item in the folder list view.
+    AddChildView(top_icon_views_[i]);
+    top_icon_views_[i]->SetBoundsRect(
+        app_list_folder_view_->ConvertRectToParent(
+            app_list_folder_view_->GetItemIconBoundsAt(i)));
+    static_cast<TopIconAnimationView*>(top_icon_views_[i])->TransformView();
+  }
+}
+
 }  // namespace app_list