home screen: Fix snap preview animations when dragging window from shelf

The present CL is a new way to serve the same purpose as [1]. As
SplitViewDragIndicators::WindowDraggingState has values called
kFromOverview and kFromTop, I think it is most intuitive to add one
called kFromShelf, with the caveat that the difference between kNoDrag
and kFromShelf is all about animations. Compared to [1], I think it is
nice to avoid adding a whole extra member variable.

[1] https://chromium-review.googlesource.com/c/chromium/src/+/1894754

Test: ash_unittests DragWindowFromShelfControllerTest.SplitViewDragIndicatorsWindowDraggingStates
Test: ash_unittests SplitViewDragIndicatorsTest.SplitViewDragIndicatorsVisibility
Fixed: 1020349
Change-Id: I69aefae3a68579d2f0d0c61a8d8f5588689d0b13
Bug: 1020349
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1898771
Commit-Queue: Avery Musbach <amusbach@chromium.org>
Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#713270}

ash/home_screen/drag_window_from_shelf_controller.cc

@@ -160,13 +160,10 @@ void DragWindowFromShelfController::Drag(const gfx::Point& location_in_screen,
   if (overview_controller->InOverviewSession()) {
     const SplitViewController::SnapPosition snap_position =
         GetSnapPosition(location_in_screen);
-    // Pass non_snap_state=kNoDrag so that only snap previews show up.
-    // TODO(crbug.com/1020349): Achieve that effect another way, because this
-    // way causes incorrect animations.
     SplitViewDragIndicators::WindowDraggingState window_dragging_state =
         SplitViewDragIndicators::ComputeWindowDraggingState(
             drag_started_,
-            SplitViewDragIndicators::WindowDraggingState::kNoDrag,
+            SplitViewDragIndicators::WindowDraggingState::kFromShelf,
             snap_position);
     OverviewSession* overview_session = overview_controller->overview_session();
     overview_session->SetSplitViewDragIndicatorsWindowDraggingState(

ash/home_screen/drag_window_from_shelf_controller_unittest.cc

@@ -447,8 +447,9 @@ TEST_F(DragWindowFromShelfControllerTest, HideOverviewDuringDragging) {
   EXPECT_EQ(window1->layer()->GetTargetOpacity(), 1.f);
 }
 
-// Test there is no drag-to-snap or cannot-snap drag indicators during dragging.
-TEST_F(DragWindowFromShelfControllerTest, NoDragToSnapIndicator) {
+// Check the split view drag indicators window dragging states.
+TEST_F(DragWindowFromShelfControllerTest,
+       SplitViewDragIndicatorsWindowDraggingStates) {
   UpdateDisplay("400x400");
   const gfx::Rect shelf_bounds =
       Shelf::ForWindow(Shell::GetPrimaryRootWindow())->GetIdealBounds();
@@ -462,14 +463,30 @@ TEST_F(DragWindowFromShelfControllerTest, NoDragToSnapIndicator) {
   SplitViewDragIndicators::WindowDraggingState window_dragging_state =
       overview_session->split_view_drag_indicators()
           ->current_window_dragging_state();
-  EXPECT_EQ(SplitViewDragIndicators::WindowDraggingState::kNoDrag,
+  EXPECT_EQ(SplitViewDragIndicators::WindowDraggingState::kFromShelf,
+            window_dragging_state);
+
+  Drag(gfx::Point(0, 200), 0.5f, 0.5f);
+  window_dragging_state = overview_session->split_view_drag_indicators()
+                              ->current_window_dragging_state();
+  EXPECT_EQ(SplitViewDragIndicators::WindowDraggingState::kToSnapLeft,
             window_dragging_state);
 
+  Drag(gfx::Point(0, 300), 0.5f, 0.5f);
+  window_dragging_state = overview_session->split_view_drag_indicators()
+                              ->current_window_dragging_state();
+  EXPECT_EQ(SplitViewDragIndicators::WindowDraggingState::kFromShelf,
+            window_dragging_state);
   Drag(gfx::Point(0, 200), 0.5f, 0.5f);
   window_dragging_state = overview_session->split_view_drag_indicators()
                               ->current_window_dragging_state();
   EXPECT_EQ(SplitViewDragIndicators::WindowDraggingState::kToSnapLeft,
             window_dragging_state);
+  Drag(gfx::Point(200, 200), 0.5f, 0.5f);
+  window_dragging_state = overview_session->split_view_drag_indicators()
+                              ->current_window_dragging_state();
+  EXPECT_EQ(SplitViewDragIndicators::WindowDraggingState::kFromShelf,
+            window_dragging_state);
 
   EndDrag(shelf_bounds.CenterPoint(),
           /*velocity_y=*/base::nullopt);

ash/wm/splitview/split_view_drag_indicators.cc

@@ -160,12 +160,6 @@ class SplitViewDragIndicators::RotatedImageLabelView : public views::View {
       WindowDraggingState window_dragging_state,
       WindowDraggingState previous_window_dragging_state,
       bool can_dragged_window_be_snapped) {
-    // In split view, the labels never show, and they do not need to be updated.
-    if (SplitViewController::Get(GetWidget()->GetNativeWindow())
-            ->InSplitViewMode()) {
-      return;
-    }
-
     // No top label for dragging from the top in portrait orientation.
     if (window_dragging_state == WindowDraggingState::kFromTop &&
         !IsCurrentScreenOrientationLandscape() && !is_right_or_bottom_) {
@@ -274,19 +268,25 @@ class SplitViewDragIndicators::SplitViewDragIndicatorsView
     previous_window_dragging_state_ = window_dragging_state_;
     window_dragging_state_ = window_dragging_state;
 
+    const bool previews_only =
+        window_dragging_state == WindowDraggingState::kFromShelf ||
+        SplitViewController::Get(GetWidget()->GetNativeWindow())
+            ->InSplitViewMode();
     const bool can_dragged_window_be_snapped =
         dragged_window_ && CanSnapInSplitview(dragged_window_);
+    if (!previews_only) {
       left_rotated_view_->OnWindowDraggingStateChanged(
           window_dragging_state, previous_window_dragging_state_,
           can_dragged_window_be_snapped);
       right_rotated_view_->OnWindowDraggingStateChanged(
           window_dragging_state, previous_window_dragging_state_,
           can_dragged_window_be_snapped);
+    }
     left_highlight_view_->OnWindowDraggingStateChanged(
-        window_dragging_state, previous_window_dragging_state_,
+        window_dragging_state, previous_window_dragging_state_, previews_only,
         can_dragged_window_be_snapped);
     right_highlight_view_->OnWindowDraggingStateChanged(
-        window_dragging_state, previous_window_dragging_state_,
+        window_dragging_state, previous_window_dragging_state_, previews_only,
         can_dragged_window_be_snapped);
 
     if (window_dragging_state != WindowDraggingState::kNoDrag ||

ash/wm/splitview/split_view_drag_indicators.h

@@ -55,6 +55,11 @@ class ASH_EXPORT SplitViewDragIndicators {
     // snapped in split view.
     kFromTop,
 
+    // Started dragging from the shelf. Split view is supported. Not currently
+    // dragging in a snap area, or the dragged window is not eligible to be
+    // snapped in split view.
+    kFromShelf,
+
     // Currently dragging in the |SplitViewController::LEFT| snap area, and the
     // dragged window is eligible to be snapped in split view.
     kToSnapLeft,

ash/wm/splitview/split_view_drag_indicators_unittest.cc

@@ -415,6 +415,25 @@ TEST_F(SplitViewDragIndicatorsTest, SplitViewDragIndicatorsVisibility) {
       SplitViewDragIndicators::WindowDraggingState::kToSnapRight, gfx::Point());
   check_helper(indicator.get(), to_int(IndicatorType::kRightHighlight));
 
+  // Verify that only snap previews are shown for window dragging from shelf.
+  indicator->SetWindowDraggingState(
+      SplitViewDragIndicators::WindowDraggingState::kNoDrag, gfx::Point());
+  indicator->SetWindowDraggingState(
+      SplitViewDragIndicators::WindowDraggingState::kFromShelf, gfx::Point());
+  check_helper(indicator.get(), 0);
+  indicator->SetWindowDraggingState(
+      SplitViewDragIndicators::WindowDraggingState::kToSnapLeft, gfx::Point());
+  check_helper(indicator.get(), to_int(IndicatorType::kLeftHighlight));
+  indicator->SetWindowDraggingState(
+      SplitViewDragIndicators::WindowDraggingState::kFromShelf, gfx::Point());
+  check_helper(indicator.get(), 0);
+  indicator->SetWindowDraggingState(
+      SplitViewDragIndicators::WindowDraggingState::kToSnapRight, gfx::Point());
+  check_helper(indicator.get(), to_int(IndicatorType::kRightHighlight));
+  indicator->SetWindowDraggingState(
+      SplitViewDragIndicators::WindowDraggingState::kFromShelf, gfx::Point());
+  check_helper(indicator.get(), 0);
+
   ScreenOrientationControllerTestApi orientation_api(
       Shell::Get()->screen_orientation_controller());
   // Verify that everything is visible in state

ash/wm/splitview/split_view_highlight_view.cc

@@ -177,6 +177,7 @@ void SplitViewHighlightView::SetColor(SkColor color) {
 void SplitViewHighlightView::OnWindowDraggingStateChanged(
     SplitViewDragIndicators::WindowDraggingState window_dragging_state,
     SplitViewDragIndicators::WindowDraggingState previous_window_dragging_state,
+    bool previews_only,
     bool can_dragged_window_be_snapped) {
   // No top indicator for dragging from the top in portrait orientation.
   if (window_dragging_state ==
@@ -212,10 +213,6 @@ void SplitViewHighlightView::OnWindowDraggingStateChanged(
     return;
   }
 
-  const bool previews_only =
-      SplitViewController::Get(GetWidget()->GetNativeWindow())
-          ->InSplitViewMode();
-
   if (previous_preview_position != SplitViewController::NONE) {
     // There was a snap preview showing, but now the user has dragged away from
     // the edge of the screen, so that the preview should go away.

ash/wm/splitview/split_view_highlight_view.h

@@ -45,11 +45,15 @@ class ASH_EXPORT SplitViewHighlightView : public views::View {
   void SetColor(SkColor color);
 
   // Called to update the opacity of the highlights view on transition from
-  // |previous_window_dragging_state| to |window_dragging_state|.
+  // |previous_window_dragging_state| to |window_dragging_state|. If
+  // |previews_only|, then there shall be no visible drag indicators except for
+  // snap previews. The highlights are white if |can_dragged_window_be_snapped|,
+  // black otherwise.
   void OnWindowDraggingStateChanged(
       SplitViewDragIndicators::WindowDraggingState window_dragging_state,
       SplitViewDragIndicators::WindowDraggingState
           previous_window_dragging_state,
+      bool previews_only,
       bool can_dragged_window_be_snapped);
 
  private: