overview: Basic visuals for multidisplay drag, based on outside overview

See Comment 2 here:
https://bugs.chromium.org/p/chromium/issues/detail?id=961170#c2

Test: manual
Bug: 961170
Change-Id: I42509d8f4ff4cffa84441ea392b56a68ac8d608b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1627910
Commit-Queue: Avery Musbach <amusbach@chromium.org>
Reviewed-by: Sammie Quon <sammiequon@chromium.org>
Cr-Commit-Position: refs/heads/master@{#662885}

ash/wm/overview/overview_item.cc

@@ -15,6 +15,7 @@
 #include "ash/scoped_animation_disabler.h"
 #include "ash/shell.h"
 #include "ash/strings/grit/ash_strings.h"
+#include "ash/wm/drag_window_controller.h"
 #include "ash/wm/overview/delayed_animation_observer_impl.h"
 #include "ash/wm/overview/overview_animation_type.h"
 #include "ash/wm/overview/overview_constants.h"
@@ -702,6 +703,31 @@ void OverviewItem::OnDragAnimationCompleted() {
   }
 }
 
+void OverviewItem::UpdatePhantomsForDragging(
+    const gfx::PointF& location_in_screen) {
+  aura::Window* window = transform_window_.IsMinimized()
+                             ? item_widget_->GetNativeWindow()
+                             : GetWindow();
+
+  if (!phantoms_for_dragging_) {
+    DCHECK_EQ(1.f, window->layer()->opacity());
+    phantoms_for_dragging_ = std::make_unique<DragWindowController>(window);
+  }
+
+  const gfx::Point location = gfx::ToRoundedPoint(location_in_screen);
+  window->layer()->SetOpacity(DragWindowController::GetDragWindowOpacity(
+      root_window_, window, location));
+  phantoms_for_dragging_->Update(location);
+}
+
+void OverviewItem::DestroyPhantomsForDragging() {
+  phantoms_for_dragging_.reset();
+  aura::Window* window = transform_window_.IsMinimized()
+                             ? item_widget_->GetNativeWindow()
+                             : GetWindow();
+  window->layer()->SetOpacity(1.f);
+}
+
 void OverviewItem::SetShadowBounds(base::Optional<gfx::Rect> bounds_in_screen) {
   // Shadow is normally turned off during animations and reapplied when they
   // are finished. On destruction, |shadow_| is cleaned up before

ash/wm/overview/overview_item.h

@@ -29,6 +29,7 @@ class Widget;
 }  // namespace views
 
 namespace ash {
+class DragWindowController;
 class OverviewGrid;
 class RoundedLabelWidget;
 
@@ -162,6 +163,12 @@ class ASH_EXPORT OverviewItem : public CaptionContainerView::EventDelegate,
   // when entering overview.
   void OnDragAnimationCompleted();
 
+  // Updates |phantoms_for_dragging_|. If |phantoms_for_dragging_| is null, then
+  // a new object is created for it.
+  void UpdatePhantomsForDragging(const gfx::PointF& location_in_screen);
+
+  void DestroyPhantomsForDragging();
+
   // Sets the bounds of the window shadow. If |bounds_in_screen| is nullopt,
   // the shadow is hidden.
   void SetShadowBounds(base::Optional<gfx::Rect> bounds_in_screen);
@@ -315,6 +322,10 @@ class ASH_EXPORT OverviewItem : public CaptionContainerView::EventDelegate,
   // users this window cannot be snapped.
   std::unique_ptr<RoundedLabelWidget> cannot_snap_widget_;
 
+  // Responsible for phantoms that look like the window on all displays during
+  // dragging.
+  std::unique_ptr<DragWindowController> phantoms_for_dragging_;
+
   // Pointer to the Overview that owns the OverviewGrid containing |this|.
   // Guaranteed to be non-null for the lifetime of |this|.
   OverviewSession* overview_session_;

ash/wm/overview/overview_window_drag_controller.cc

@@ -6,6 +6,7 @@
 
 #include <memory>
 
+#include "ash/display/mouse_cursor_event_filter.h"
 #include "ash/public/cpp/ash_features.h"
 #include "ash/public/cpp/presentation_time_recorder.h"
 #include "ash/screen_util.h"
@@ -146,6 +147,8 @@ void OverviewWindowDragController::Drag(const gfx::PointF& location_in_screen) {
     presentation_time_recorder_->RequestNext();
 
   item_->SetBounds(bounds, OVERVIEW_ANIMATION_NONE);
+  if (current_drag_behavior_ == DragBehavior::kNormalDrag)
+    item_->UpdatePhantomsForDragging(location_in_screen);
 }
 
 OverviewWindowDragController::DragResult
@@ -182,6 +185,8 @@ void OverviewWindowDragController::StartNormalDragMode(
     const gfx::PointF& location_in_screen) {
   did_move_ = true;
   current_drag_behavior_ = DragBehavior::kNormalDrag;
+  Shell::Get()->mouse_cursor_filter()->ShowSharedEdgeIndicator(
+      item_->root_window());
   item_->ScaleUpSelectedItem(
       OVERVIEW_ANIMATION_LAYOUT_OVERVIEW_ITEMS_IN_OVERVIEW);
   original_scaled_size_ = item_->target_bounds().size();
@@ -247,6 +252,8 @@ void OverviewWindowDragController::ActivateDraggedWindow() {
 
 void OverviewWindowDragController::ResetGesture() {
   if (current_drag_behavior_ == DragBehavior::kNormalDrag) {
+    Shell::Get()->mouse_cursor_filter()->HideSharedEdgeIndicator();
+    item_->DestroyPhantomsForDragging();
     overview_session_->RemoveDropTargetForDraggingFromOverview(item_);
     overview_session_->SetSplitViewDragIndicatorsIndicatorState(
         IndicatorState::kNone, gfx::Point());
@@ -353,6 +360,8 @@ OverviewWindowDragController::DragResult
 OverviewWindowDragController::CompleteNormalDrag(
     const gfx::PointF& location_in_screen) {
   DCHECK_EQ(current_drag_behavior_, DragBehavior::kNormalDrag);
+  Shell::Get()->mouse_cursor_filter()->HideSharedEdgeIndicator();
+  item_->DestroyPhantomsForDragging();
 
   const gfx::Point rounded_screen_point =
       gfx::ToRoundedPoint(location_in_screen);