Keep split window snapped after dragging is cancelled

Bug: 1033309
Change-Id: I0a94a67e18a97137588ad27d49288673727eb68b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2342466
Commit-Queue: Xiaodan Zhu <zxdan@chromium.org>
Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
Cr-Commit-Position: refs/heads/master@{#796608}

ash/home_screen/drag_window_from_shelf_controller.cc

@@ -306,9 +306,11 @@ void DragWindowFromShelfController::CancelDrag() {
   ReshowHiddenWindowsOnDragEnd();
 
   window_drag_result_ = ShelfWindowDragResult::kDragCanceled;
+  // When the drag is cancelled, the window should restore to its original snap
+  // position.
   OnDragEnded(previous_location_in_screen_,
               /*should_drop_window_in_overview=*/false,
-              /*snap_position=*/SplitViewController::NONE);
+              /*snap_position=*/initial_snap_position_);
   WindowState::Get(window_)->DeleteDragDetails();
 }
 
@@ -376,6 +378,11 @@ void DragWindowFromShelfController::OnDragStarted(
   // to be detached from splitview before start dragging.
   SplitViewController* split_view_controller =
       SplitViewController::Get(Shell::GetPrimaryRootWindow());
+  // Preserve initial snap position
+  if (split_view_controller->IsWindowInSplitView(window_)) {
+    initial_snap_position_ =
+        split_view_controller->GetPositionOfSnappedWindow(window_);
+  }
   split_view_controller->OnWindowDragStarted(window_);
   // Note SplitViewController::OnWindowDragStarted() may open overview.
   if (Shell::Get()->overview_controller()->InOverviewSession())
@@ -569,11 +576,15 @@ DragWindowFromShelfController::GetSnapPositionOnDragEnd(
     const gfx::PointF& location_in_screen,
     base::Optional<float> velocity_y) const {
   if (!Shell::Get()->overview_controller()->InOverviewSession() ||
-      ShouldRestoreToOriginalBounds(location_in_screen) ||
       ShouldGoToHomeScreen(location_in_screen, velocity_y)) {
     return SplitViewController::NONE;
   }
 
+  // When dragging ends but restore to original bounds, we should restore
+  // window's initial snap position
+  if (ShouldRestoreToOriginalBounds(location_in_screen))
+    return initial_snap_position_;
+
   return GetSnapPosition(location_in_screen);
 }
 

ash/home_screen/drag_window_from_shelf_controller.h

@@ -205,6 +205,9 @@ class ASH_EXPORT DragWindowFromShelfController : public aura::WindowObserver {
 
   bool during_window_restoration_callback_ = false;
 
+  SplitViewController::SnapPosition initial_snap_position_ =
+      SplitViewController::NONE;
+
   SplitViewController::SnapPosition end_snap_position_ =
       SplitViewController::NONE;
 

ash/home_screen/drag_window_from_shelf_controller_unittest.cc

@@ -1154,4 +1154,56 @@ TEST_F(DragWindowFromShelfControllerTest, DropsIntoOverviewAtCorrectPosition) {
                     parent));
 }
 
+// Tests that when dragging a snapped window is cancelled, the window
+// still keep at the original snap position.
+TEST_F(DragWindowFromShelfControllerTest,
+       KeepSplitWindowSnappedAfterRestoreToOriginalBounds) {
+  UpdateDisplay("400x400");
+  const gfx::Rect shelf_bounds =
+      Shelf::ForWindow(Shell::GetPrimaryRootWindow())->GetIdealBounds();
+
+  auto window1 = CreateTestWindow();
+  auto window2 = CreateTestWindow();
+
+  // In splitview mode, the snapped windows will stay visible during dragging.
+  split_view_controller()->SnapWindow(window1.get(), SplitViewController::LEFT);
+  split_view_controller()->SnapWindow(window2.get(),
+                                      SplitViewController::RIGHT);
+
+  // Try to drag a left snapped window from shelf, but finally restore to
+  // original bounds.
+  StartDrag(window1.get(), shelf_bounds.left_center(), HotseatState::kExtended);
+  Drag(gfx::Point(0, 200), 1.f, 1.f);
+  EndDrag(shelf_bounds.bottom_left(), /*velocity_y=*/base::nullopt);
+  // Ensure that the window still keep its initial snap position.
+  EXPECT_TRUE(split_view_controller()->IsWindowInSplitView(window1.get()));
+  EXPECT_EQ(split_view_controller()->GetPositionOfSnappedWindow(window1.get()),
+            SplitViewController::LEFT);
+  // Try to drag a right snapped window from shelf, and finally drop to
+  // overview.
+  StartDrag(window2.get(), shelf_bounds.right_center(),
+            HotseatState::kExtended);
+  Drag(gfx::Point(400, 200), 1.f, 1.f);
+  DragWindowFromShelfControllerTestApi().WaitUntilOverviewIsShown(
+      window_drag_controller());
+  OverviewController* overview_controller = Shell::Get()->overview_controller();
+  OverviewSession* overview_session = overview_controller->overview_session();
+  EndDrag(gfx::Point(200, 200), /*velocity_y=*/base::nullopt);
+  // Ensure that the window is not in splitview but in overview.
+  EXPECT_FALSE(split_view_controller()->IsWindowInSplitView(window2.get()));
+  EXPECT_TRUE(overview_session->IsWindowInOverview(window2.get()));
+
+  // Try to drag the left window again within the restore distance.
+  StartDrag(window1.get(), shelf_bounds.left_center(), HotseatState::kExtended);
+  Drag(gfx::Point(0, 200), 1.f, 1.f);
+  EndDrag(shelf_bounds.bottom_left(), /*velocity_y=*/base::nullopt);
+  // Ensure that the left window still keep snapped.
+  EXPECT_TRUE(split_view_controller()->IsWindowInSplitView(window1.get()));
+  EXPECT_EQ(split_view_controller()->GetPositionOfSnappedWindow(window1.get()),
+            SplitViewController::LEFT);
+  // Ensure that the right window is still in the overview.
+  EXPECT_FALSE(split_view_controller()->IsWindowInSplitView(window2.get()));
+  EXPECT_TRUE(overview_session->IsWindowInOverview(window2.get()));
+}
+
 }  // namespace ash