Ash Tray: Add fade out animation for notification controls when sliding.

This change removes a double slide animation when the user flings to
dismiss a notification.

TEST=manually verified, new unit test
BUG=933640

Change-Id: I7f9f4e558dfa53e8acf0abdbd86cf4449c1ea891
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1583344
Commit-Queue: Tim Song <tengs@chromium.org>
Reviewed-by: Tetsui Ohkubo <tetsui@chromium.org>
Cr-Commit-Position: refs/heads/master@{#654564}

ash/system/message_center/message_center_style.h

@@ -29,6 +29,10 @@ constexpr int kSwipeControlButtonHorizontalMargin = 8;
 constexpr SkColor kSwipeControlBackgroundColor =
     SkColorSetRGB(0xee, 0xee, 0xee);
 
+// The ratio to multiply with the swipe control width to get the width to
+// display at full opacity when swiping.
+constexpr float kSwipeControlFullOpacityRatio = 1.5f;
+
 }  // namespace message_center_style
 
 }  // namespace ash

ash/system/message_center/notification_swipe_control_view.cc

@@ -88,6 +88,19 @@ void NotificationSwipeControlView::UpdateButtonsVisibility() {
       message_center_style::kSwipeControlButtonHorizontalMargin *
           (control_button_count + 1);
   message_view_->SetSlideButtonWidth(control_button_width);
+
+  // Update opacity based on the swipe progress. The swipe controls should
+  // gradually disappear as the user swipes the notification away.
+  float full_opacity_width =
+      message_center_style::kSwipeControlFullOpacityRatio *
+      control_button_width;
+  float fade_out_width = message_view_->width() - full_opacity_width;
+  DCHECK(fade_out_width > 0);
+  float swipe_progress = std::max(
+      0.0f, (fabs(gesture_amount) - full_opacity_width) / fade_out_width);
+  float opacity = std::max(0.0f, 1.0f - swipe_progress);
+
+  layer()->SetOpacity(opacity);
 }
 
 void NotificationSwipeControlView::UpdateCornerRadius(int top_radius,

ash/system/message_center/unified_message_list_view.cc

@@ -157,6 +157,10 @@ class UnifiedMessageListView::MessageViewContainer
     control_view_->UpdateButtonsVisibility();
   }
 
+  void OnSlideOut(const std::string& notification_id) override {
+    is_slid_out_by_user_ = true;
+  }
+
   gfx::Rect start_bounds() const { return start_bounds_; }
   gfx::Rect ideal_bounds() const { return ideal_bounds_; }
   bool is_removed() const { return is_removed_; }
@@ -171,6 +175,8 @@ class UnifiedMessageListView::MessageViewContainer
 
   void set_is_removed() { is_removed_ = true; }
 
+  bool is_slid_out_by_user() { return is_slid_out_by_user_; }
+
  private:
   // The bounds that the container starts animating from. If not animating, it's
   // ignored.
@@ -184,6 +190,9 @@ class UnifiedMessageListView::MessageViewContainer
   // Unused if |state_| is not SLIDE_OUT.
   bool is_removed_ = false;
 
+  // True if the notification is slid out completely by the user.
+  bool is_slid_out_by_user_ = false;
+
   MessageView* const message_view_;
   NotificationSwipeControlView* const control_view_;
 
@@ -334,9 +343,12 @@ void UnifiedMessageListView::OnNotificationRemoved(const std::string& id,
   if (child)
     child->set_is_removed();
 
+  if (child->is_slid_out_by_user())
+    DeleteRemovedNotifications();
+
   UpdateBounds();
 
-  state_ = State::SLIDE_OUT;
+  state_ = child->is_slid_out_by_user() ? State::MOVE_DOWN : State::SLIDE_OUT;
   StartAnimation();
 }
 

ash/system/message_center/unified_message_list_view_unittest.cc

@@ -512,4 +512,29 @@ TEST_F(UnifiedMessageListViewTest, ClearAllWithPinnedNotifications) {
   EXPECT_EQ(1u, message_list_view()->children().size());
 }
 
+TEST_F(UnifiedMessageListViewTest, UserSwipesAwayNotification) {
+  // Show message list with two notifications.
+  AddNotification();
+  AddNotification();
+  CreateMessageListView();
+
+  // Start swiping the notification away.
+  GetMessageViewAt(1)->OnSlideStarted();
+  GetMessageViewAt(1)->OnSlideChanged(true);
+  EXPECT_EQ(2u, MessageCenter::Get()->GetVisibleNotifications().size());
+  EXPECT_EQ(2u, message_list_view()->children().size());
+
+  // Swiping away the notification should remove it both in the MessageCenter
+  // and the MessageListView.
+  GetMessageViewAt(1)->OnSlideOut();
+  EXPECT_EQ(1u, MessageCenter::Get()->GetVisibleNotifications().size());
+  EXPECT_EQ(1u, message_list_view()->children().size());
+
+  // The next and only animation should be the move down animation.
+  int previous_height = message_list_view()->GetPreferredSize().height();
+  AnimateToEnd();
+  EXPECT_GT(previous_height, message_list_view()->GetPreferredSize().height());
+  EXPECT_FALSE(message_list_view()->IsAnimating());
+}
+
 }  // namespace ash

ui/message_center/views/message_view.cc

@@ -320,6 +320,9 @@ void MessageView::AddSlideObserver(MessageView::SlideObserver* observer) {
 }
 
 void MessageView::OnSlideOut() {
+  for (auto* observer : slide_observers_)
+    observer->OnSlideOut(notification_id_);
+
   MessageCenter::Get()->RemoveNotification(notification_id_,
                                            true /* by_user */);
 }

ui/message_center/views/message_view.h

@@ -54,6 +54,7 @@ class MESSAGE_CENTER_EXPORT MessageView : public views::InkDropHostView,
 
     virtual void OnSlideStarted(const std::string& notification_id) {}
     virtual void OnSlideChanged(const std::string& notification_id) {}
+    virtual void OnSlideOut(const std::string& notification_id) {}
   };
 
   enum class Mode {

ui/message_center/views/slide_out_controller.cc

@@ -132,9 +132,11 @@ void SlideOutController::RestoreVisualState() {
       gesture_amount_ = 0.f;
       break;
     case SwipeControlOpenState::OPEN_ON_RIGHT:
+      gesture_amount_ = -swipe_control_width_;
       transform.Translate(-swipe_control_width_, 0);
       break;
     case SwipeControlOpenState::OPEN_ON_LEFT:
+      gesture_amount_ = swipe_control_width_;
       transform.Translate(swipe_control_width_, 0);
       break;
   }