Per pixel launcher dragging

Use PointF/float to calculate Y position, then use
SubpixelPositionOffset to move the window to pixel position.

Reset to DP position when moving to the specific state.

   requires a fix to event generator.

Bug: 1042754, 1038998
Test: Maually tested. unit tests will be added in a separate CL as it
Change-Id: I6157f46bc00929e03379a4b3e80e9b5b75ed72ad
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2002863
Commit-Queue: Mitsuru Oshima <oshima@chromium.org>
Reviewed-by: Alex Newcomer <newcomer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#732997}

ash/app_list/app_list_controller_impl.cc

@@ -1309,7 +1309,9 @@ bool AppListControllerImpl::ShouldDismissImmediately() {
       Shelf::ForWindow(presenter_.GetView()->GetWidget()->GetNativeView())
           ->GetIdealBounds()
           .y();
-  const int current_y = presenter_.GetView()->GetBoundsInScreen().y();
+
+  const int current_y =
+      presenter_.GetView()->GetWidget()->GetNativeWindow()->bounds().y();
   return current_y > ideal_shelf_y;
 }
 

ash/app_list/app_list_presenter_impl.cc

@@ -243,7 +243,7 @@ bool AppListPresenterImpl::GetTargetVisibility() const {
   return is_target_visibility_show_;
 }
 
-void AppListPresenterImpl::UpdateYPositionAndOpacity(int y_position_in_screen,
+void AppListPresenterImpl::UpdateYPositionAndOpacity(float y_position_in_screen,
                                                      float background_opacity) {
   if (!is_target_visibility_show_)
     return;
@@ -264,7 +264,7 @@ void AppListPresenterImpl::ProcessMouseWheelOffset(
 }
 
 void AppListPresenterImpl::UpdateYPositionAndOpacityForHomeLauncher(
-    int y_position_in_screen,
+    float y_position_in_screen,
     float opacity,
     base::Optional<TabletModeAnimationTransition> transition,
     UpdateHomeLauncherAnimationSettingsCallback callback) {
@@ -283,7 +283,7 @@ void AppListPresenterImpl::UpdateYPositionAndOpacityForHomeLauncher(
   }
 
   const gfx::Transform translation(1.f, 0.f, 0.f, 1.f, 0.f,
-                                   static_cast<float>(y_position_in_screen));
+                                   y_position_in_screen);
   if (layer->GetAnimator()->is_animating()) {
     layer->GetAnimator()->StopAnimating();
 

ash/app_list/app_list_presenter_impl.h

@@ -93,7 +93,7 @@ class APP_LIST_EXPORT AppListPresenterImpl
   bool GetTargetVisibility() const;
 
   // Updates y position and opacity of app list.
-  void UpdateYPositionAndOpacity(int y_position_in_screen,
+  void UpdateYPositionAndOpacity(float y_position_in_screen,
                                  float background_opacity);
 
   // Ends the drag of app list from shelf.
@@ -110,7 +110,7 @@ class APP_LIST_EXPORT AppListPresenterImpl
   // |callback| is non-null. If not set, the animation smoothness metrics will
   // not be reported.
   void UpdateYPositionAndOpacityForHomeLauncher(
-      int y_position_in_screen,
+      float y_position_in_screen,
       float opacity,
       base::Optional<TabletModeAnimationTransition> transition,
       UpdateHomeLauncherAnimationSettingsCallback callback);

ash/app_list/views/app_list_view.h

@@ -212,7 +212,7 @@ class APP_LIST_EXPORT AppListView : public views::WidgetDelegateView,
                                  bool triggered_by_contents_change);
 
   // Updates y position and opacity of app list during dragging.
-  void UpdateYPositionAndOpacity(int y_position_in_screen,
+  void UpdateYPositionAndOpacity(float y_position_in_screen,
                                  float background_opacity);
 
   // Offsets the y position of the app list (above the screen)
@@ -398,15 +398,15 @@ class APP_LIST_EXPORT AppListView : public views::WidgetDelegateView,
   void HandleClickOrTap(ui::LocatedEvent* event);
 
   // Initializes |initial_drag_point_|.
-  void StartDrag(const gfx::Point& location);
+  void StartDrag(const gfx::PointF& location_in_root);
 
   // Updates the bounds of the widget while maintaining the relative position
   // of the top of the widget and the gesture.
-  void UpdateDrag(const gfx::Point& location);
+  void UpdateDrag(const gfx::PointF& location_in_root);
 
   // Handles app list state transfers. If the drag was fast enough, ignore the
   // release position and snap to the next state.
-  void EndDrag(const gfx::Point& location);
+  void EndDrag(const gfx::PointF& location_in_root);
 
   // Set child views for |target_state|.
   void SetChildViewsForStateTransition(AppListViewState target_state);
@@ -492,6 +492,10 @@ class APP_LIST_EXPORT AppListView : public views::WidgetDelegateView,
   // |state| and |is_in_drag_|.
   void UpdateAppListBackgroundYPosition(AppListViewState state);
 
+  // Reset the subpixel position offset of the |layer| so that it's DP origin
+  // is snapped.
+  void ResetSubpixelPositionOffset(ui::Layer* layer);
+
   AppListViewDelegate* delegate_;    // Weak. Owned by AppListService.
   AppListModel* const model_;        // Not Owned.
   SearchModel* const search_model_;  // Not Owned.
@@ -524,22 +528,19 @@ class APP_LIST_EXPORT AppListView : public views::WidgetDelegateView,
   // Whether the view is being built.
   bool is_building_ = false;
 
-  // Y position of the app list in screen space coordinate during dragging.
-  int app_list_y_position_in_screen_ = 0;
-
   // The opacity of app list background during dragging. This ensures a gradual
   // opacity shift from the shelf opacity while dragging to show the AppListView
   // from the shelf.
   float background_opacity_in_drag_ = 0.f;
 
-  // The location of initial gesture event in screen coordinates.
-  gfx::Point initial_drag_point_;
+  // The location of initial gesture event in root window coordinates.
+  gfx::PointF initial_drag_point_;
 
-  // The rectangle of initial widget's window in screen coordinates.
-  gfx::Rect initial_window_bounds_;
+  // The offset to the widget from dragging location.
+  float drag_offset_;
 
-  // The location of the initial mouse event in view coordinates.
-  gfx::Point initial_mouse_drag_point_;
+  // The location of the initial mouse event in root window coordinates.
+  gfx::PointF initial_mouse_drag_point_;
 
   // The velocity of the gesture event.
   float last_fling_velocity_ = 0;

ash/shelf/shelf_layout_manager.cc

@@ -2382,11 +2382,12 @@ void ShelfLayoutManager::UpdateDrag(const ui::LocatedEvent& event_in_screen,
       return;
     }
     const gfx::Rect shelf_bounds = GetIdealBounds();
+    float y_position_in_root = std::min(event_in_screen.root_location_f().y(),
+                                        static_cast<float>(shelf_bounds.y()));
     Shell::Get()->app_list_controller()->UpdateYPositionAndOpacity(
-        std::min(event_in_screen.location().y(), shelf_bounds.y()),
-        GetAppListBackgroundOpacityOnShelfOpacity());
+        y_position_in_root, GetAppListBackgroundOpacityOnShelfOpacity());
     launcher_above_shelf_bottom_amount_ =
-        shelf_bounds.bottom() - event_in_screen.location().y();
+        shelf_bounds.bottom() - event_in_screen.root_location().y();
   } else {
     if (drag_start_point_in_screen_ == gfx::Point())
       drag_start_point_in_screen_ = event_in_screen.location();