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

ui/app_list/app_list_folder_item.cc

Index: ui/app_list/app_list_folder_item.cc
diff --git a/ui/app_list/app_list_folder_item.cc b/ui/app_list/app_list_folder_item.cc
index 38bce3011e7e0d62477ef05495c29650b59bf107..55ac8d5548c7b1c9c89362a85623382256f69ddd 100644
--- a/ui/app_list/app_list_folder_item.cc
+++ b/ui/app_list/app_list_folder_item.cc
@@ -14,8 +14,6 @@ namespace app_list {
 
 namespace {
 
-const int kIconDimension = 48;
-const size_t kNumTopApps = 4;
 const int kItemIconDimension = 16;
 
 // Generates the folder icon with the top 4 child item icons laid in 2x2 tile.
@@ -27,7 +25,7 @@ class FolderImageSource : public gfx::CanvasImageSource {
       : gfx::CanvasImageSource(size, false),
         icons_(icons),
         size_(size) {
-    DCHECK(icons.size() <= kNumTopApps);
+    DCHECK(icons.size() <= kNumFolderTopItems);
   }
 
   virtual ~FolderImageSource() {}
@@ -57,30 +55,16 @@ class FolderImageSource : public gfx::CanvasImageSource {
     if (icons_.size() == 0)
       return;
 
-    // Tiled icon coordinates.
-    const int delta_to_center = 1;
+    // Draw top items' icons.
     const gfx::Size item_icon_size =
         gfx::Size(kItemIconDimension, kItemIconDimension);
-    int left_x = center.x() - item_icon_size.width() - delta_to_center;
-    int top_y = center.y() - item_icon_size.height() - delta_to_center;
-    int right_x = center.x() + delta_to_center;
-    int bottom_y = center.y() + delta_to_center;
-
-    // top left icon
-    size_t i = 0;
-    DrawIcon(canvas, icons_[i++], item_icon_size, left_x, top_y);
-
-    // top right icon
-    if (i < icons_.size())
-      DrawIcon(canvas, icons_[i++], item_icon_size, right_x, top_y);
-
-    // left bottm icon
-    if (i < icons_.size())
-      DrawIcon(canvas, icons_[i++], item_icon_size, left_x, bottom_y);
-
-    // right bottom icon
-    if (i < icons_.size())
-      DrawIcon(canvas, icons_[i], item_icon_size, right_x, bottom_y);
+    Rects top_icon_bounds =
+        AppListFolderItem::GetTopIconsBounds(gfx::Rect(size()));
+
+    for (size_t i= 0; i < kNumFolderTopItems && i < icons_.size(); ++i) {
+      DrawIcon(canvas, icons_[i], item_icon_size,
+               top_icon_bounds[i].x(), top_icon_bounds[i].y());
+    }
   }
 
   Icons icons_;
@@ -108,13 +92,19 @@ void AppListFolderItem::UpdateIcon() {
   for (size_t i = 0; i < top_items_.size(); ++i)
     top_icons.push_back(top_items_[i]->icon());
 
-  const gfx::Size icon_size = gfx::Size(kIconDimension, kIconDimension);
+  const gfx::Size icon_size =
+      gfx::Size(kPreferredIconDimension, kPreferredIconDimension);
   gfx::ImageSkia icon = gfx::ImageSkia(
       new FolderImageSource(top_icons, icon_size),
       icon_size);
   SetIcon(icon, false);
 }
 
+const gfx::ImageSkia& AppListFolderItem::GetTopIcon(size_t item_index) {
+  DCHECK(item_index <= top_items_.size());
+  return top_items_[item_index]->icon();
+}
+
 void AppListFolderItem::Activate(int event_flags) {
   // Folder handling is implemented by the View, so do nothing.
 }
@@ -122,6 +112,38 @@ void AppListFolderItem::Activate(int event_flags) {
 // static
 const char AppListFolderItem::kAppType[] = "FolderItem";
 
+// static
+Rects AppListFolderItem::GetTopIconsBounds(
+    const gfx::Rect& folder_icon_bounds) {
+  const int delta_to_center = 1;
+  gfx::Point icon_center = folder_icon_bounds.CenterPoint();
+  Rects top_icon_bounds;
+
+  // Get the top left icon bounds.
+  int left_x = icon_center.x() - kItemIconDimension - delta_to_center;
+  int top_y = icon_center.y() - kItemIconDimension - delta_to_center;
+  gfx::Rect top_left(left_x, top_y, kItemIconDimension, kItemIconDimension);
+  top_icon_bounds.push_back(top_left);
+
+  // Get the top right icon bounds.
+  int right_x = icon_center.x() + delta_to_center;
+  gfx::Rect top_right(right_x, top_y, kItemIconDimension, kItemIconDimension);
+  top_icon_bounds.push_back(top_right);
+
+  // Get the bottom left icon bounds.
+  int bottom_y = icon_center.y() + delta_to_center;
+  gfx::Rect bottom_left(
+      left_x, bottom_y, kItemIconDimension, kItemIconDimension);
+  top_icon_bounds.push_back(bottom_left);
+
+  // Get the bottom right icon bounds.
+  gfx::Rect bottom_right(
+      right_x, bottom_y, kItemIconDimension, kItemIconDimension);
+  top_icon_bounds.push_back(bottom_right);
+
+  return top_icon_bounds;
+}
+
 const char* AppListFolderItem::GetAppType() const {
   return AppListFolderItem::kAppType;
 }
@@ -149,20 +171,20 @@ void AppListFolderItem::ItemPercentDownloadedChanged() {
 
 void AppListFolderItem::OnListItemAdded(size_t index,
                                         AppListItem* item) {
-  if (index <= kNumTopApps)
+  if (index <= kNumFolderTopItems)
     UpdateTopItems();
 }
 
 void AppListFolderItem::OnListItemRemoved(size_t index,
                                           AppListItem* item) {
-  if (index <= kNumTopApps)
+  if (index <= kNumFolderTopItems)
     UpdateTopItems();
 }
 
 void AppListFolderItem::OnListItemMoved(size_t from_index,
                                         size_t to_index,
                                         AppListItem* item) {
-  if (from_index <= kNumTopApps || to_index <= kNumTopApps)
+  if (from_index <= kNumFolderTopItems || to_index <= kNumFolderTopItems)
     UpdateTopItems();
 }
 
@@ -172,7 +194,7 @@ void AppListFolderItem::UpdateTopItems() {
   top_items_.clear();
 
   for (size_t i = 0;
-       i < kNumTopApps && i < item_list_->item_count(); ++i) {
+       i < kNumFolderTopItems && i < item_list_->item_count(); ++i) {
     AppListItem* item = item_list_->item_at(i);
     item->AddObserver(this);
     top_items_.push_back(item);