shelf: When dragged item is ripped off, hide it on shelf on all displays

The present CL fixes a bug where if you rip an item off the shelf on one
display, it shows at the right or bottom of the shelf on other displays.

Test: manual
Change-Id: I75813306ec0a11f3ac4ec39ed08ad736e5788fa0
Fixed: 1014721
Bug: 1014721
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2161900
Commit-Queue: Avery Musbach <amusbach@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#762017}

ash/public/cpp/shelf_model.cc

@@ -232,6 +232,16 @@ void ShelfModel::OnItemStatusChanged(const ShelfID& id) {
     observer.ShelfItemStatusChanged(id);
 }
 
+void ShelfModel::OnItemRippedOff() {
+  for (auto& observer : observers_)
+    observer.ShelfItemRippedOff();
+}
+
+void ShelfModel::OnItemReturnedFromRipOff(int index) {
+  for (auto& observer : observers_)
+    observer.ShelfItemReturnedFromRipOff(index);
+}
+
 void ShelfModel::RemoveNotificationRecord(const std::string& notification_id) {
   auto notification_id_it = notification_id_to_app_id_.find(notification_id);
 

ash/public/cpp/shelf_model.h

@@ -120,6 +120,14 @@ class ASH_PUBLIC_EXPORT ShelfModel {
   // has changed.
   void OnItemStatusChanged(const ShelfID& id);
 
+  // Notifies observers that an item has been dragged off the shelf (it is still
+  // being dragged).
+  void OnItemRippedOff();
+
+  // Notifies observers that an item that was dragged off the shelf has been
+  // dragged back onto the shelf (it is still being dragged).
+  void OnItemReturnedFromRipOff(int index);
+
   // Adds a record of the notification with this app id and notifies observers.
   void AddNotificationRecord(const std::string& app_id,
                              const std::string& notification_id);

ash/public/cpp/shelf_model_observer.h

@@ -41,6 +41,13 @@ class ASH_PUBLIC_EXPORT ShelfModelObserver {
   // event.
   virtual void ShelfItemStatusChanged(const ShelfID& id) {}
 
+  // Invoked after an item is dragged off the shelf (it is still being dragged).
+  virtual void ShelfItemRippedOff() {}
+
+  // Invoked after an item that has been dragged off the shelf is dragged back
+  // onto the shelf (it is still being dragged).
+  virtual void ShelfItemReturnedFromRipOff(int index) {}
+
  protected:
   virtual ~ShelfModelObserver() {}
 };

ash/shelf/shelf_view.cc

@@ -1301,6 +1301,8 @@ void ShelfView::ContinueDrag(const ui::LocatedEvent& event) {
   DCHECK(drag_view_);
   DCHECK_NE(-1, view_model_->GetIndexOfView(drag_view_));
 
+  const bool dragged_off_shelf_before = dragged_off_shelf_;
+
   // Handle rip off functionality if this is not a drag and drop host operation
   // and not the app list item.
   if (drag_and_drop_shelf_id_.IsNull() &&
@@ -1312,6 +1314,8 @@ void ShelfView::ContinueDrag(const ui::LocatedEvent& event) {
       drag_scroll_dir_ = 0;
       scrolling_timer_.Stop();
       speed_up_drag_scrolling_.Stop();
+      if (!dragged_off_shelf_before)
+        model_->OnItemRippedOff();
       return;
     }
   }
@@ -1326,6 +1330,8 @@ void ShelfView::ContinueDrag(const ui::LocatedEvent& event) {
                                           drag_point.y() - drag_origin_.y()));
   drag_and_drop_host_->UpdateDragIconProxy(drag_point_in_screen -
                                            drag_origin_.OffsetFromOrigin());
+  if (dragged_off_shelf_before)
+    model_->OnItemReturnedFromRipOff(view_model_->GetIndexOfView(drag_view_));
 }
 
 void ShelfView::MoveDragViewTo(int primary_axis_coordinate) {
@@ -1920,6 +1926,27 @@ void ShelfView::ShelfItemStatusChanged(const ShelfID& id) {
   button->SchedulePaint();
 }
 
+void ShelfView::ShelfItemRippedOff() {
+  // On the display where the drag started, there is nothing to do.
+  if (dragging())
+    return;
+  // When a dragged item has been ripped off the shelf, it is moved to the end.
+  // Now we need to hide it.
+  view_model_->view_at(model_->item_count() - 1)->layer()->SetOpacity(0.f);
+}
+
+void ShelfView::ShelfItemReturnedFromRipOff(int index) {
+  // On the display where the drag started, there is nothing to do.
+  if (dragging())
+    return;
+  // Show the item and prevent it from animating into place from the position
+  // where it was sitting with zero opacity.
+  views::View* view = view_model_->view_at(index);
+  view->SetBoundsRect(bounds_animator_->GetTargetBounds(view));
+  bounds_animator_->StopAnimatingView(view);
+  view->layer()->SetOpacity(1.f);
+}
+
 void ShelfView::OnShelfAlignmentChanged(aura::Window* root_window,
                                         ShelfAlignment old_alignment) {
   LayoutToIdealBounds();

ash/shelf/shelf_view.h

@@ -416,6 +416,8 @@ class ASH_EXPORT ShelfView : public views::AccessiblePaneView,
                                 ShelfItemDelegate* old_delegate,
                                 ShelfItemDelegate* delegate) override;
   void ShelfItemStatusChanged(const ShelfID& id) override;
+  void ShelfItemRippedOff() override;
+  void ShelfItemReturnedFromRipOff(int index) override;
 
   // Overridden from ShellObserver:
   void OnShelfAlignmentChanged(aura::Window* root_window,