Cros: Let slow swipes to the bezel hide the hotseat

Added test coverage, noticed we need to have a gesture of atleast
6px for us to register a ui::ET_GESTURE_SCROLL_UPDATE, which is
required for us to move the hotseat.

Change-Id: I73020cda89ab252fc5d7497ac9eccd1fb5e7f232
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1870051
Commit-Queue: Alex Newcomer <newcomer@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#708019}

ash/shelf/shelf_layout_manager.cc

@@ -1104,20 +1104,41 @@ HotseatState ShelfLayoutManager::CalculateHotseatState(
 
       if (shelf_widget_->hotseat_widget()->IsDraggedToExtended())
         return HotseatState::kExtended;
-      if (std::abs(last_drag_velocity_) >= 120) {
-        if (last_drag_velocity_ > 0)
-          return HotseatState::kHidden;
-        return HotseatState::kExtended;
-      }
-      const int top_of_hotseat_to_screen_bottom =
+      // |drag_amount_| is relative to the top of the hotseat when the drag
+      // begins with an extended hotseat. Correct for this to get
+      // |total_amount_dragged|.
+      const int drag_base = (state_.hotseat_state == HotseatState::kExtended &&
+                             state_.visibility_state == SHELF_VISIBLE)
+                                ? (ShelfConfig::Get()->hotseat_size() +
+                                   ShelfConfig::Get()->hotseat_bottom_padding())
+                                : 0;
+      const float total_amount_dragged = drag_base + drag_amount_;
+      const float end_of_drag_in_screen =
+          drag_start_point_in_screen_.y() + total_amount_dragged;
+      const int screen_bottom =
           display::Screen::GetScreen()
               ->GetDisplayNearestView(shelf_widget_->GetNativeView())
               .bounds()
-              .bottom() -
+              .bottom();
+      const bool dragged_to_bezel =
+          std::ceil(end_of_drag_in_screen) >= screen_bottom;
+
+      const int top_of_hotseat_to_screen_bottom =
+          screen_bottom -
           shelf_widget_->hotseat_widget()->GetWindowBoundsInScreen().y();
-      if (top_of_hotseat_to_screen_bottom <
-          ShelfConfig::Get()->hotseat_size() / 2) {
+      const bool dragged_over_half_hotseat_size =
+          top_of_hotseat_to_screen_bottom <
+          ShelfConfig::Get()->hotseat_size() / 2;
+
+      // Drags to the bezel may have large velocities, even if the drag is slow.
+      // Decide the state based on position first, before checking
+      // |last_drag_velocity_|.
+      if (dragged_to_bezel || dragged_over_half_hotseat_size)
         return HotseatState::kHidden;
+      if (std::abs(last_drag_velocity_) >= 120) {
+        if (last_drag_velocity_ > 0)
+          return HotseatState::kHidden;
+        return HotseatState::kExtended;
       }
       return HotseatState::kExtended;
     }
@@ -2112,6 +2133,8 @@ void ShelfLayoutManager::UpdateDrag(const ui::LocatedEvent& event_in_screen,
     launcher_above_shelf_bottom_amount_ =
         shelf_bounds.bottom() - event_in_screen.location().y();
   } else {
+    if (drag_start_point_in_screen_ == gfx::Point())
+      drag_start_point_in_screen_ = event_in_screen.location();
     drag_amount_ += PrimaryAxisValue(scroll_y, scroll_x);
     if (event_in_screen.type() == ui::ET_SCROLL_FLING_START) {
       last_drag_velocity_ =
@@ -2142,6 +2165,7 @@ void ShelfLayoutManager::CompleteDrag(const ui::LocatedEvent& event_in_screen) {
   UpdateVisibilityState();
   drag_status_ = kDragNone;
   hotseat_is_in_drag_ = false;
+  drag_start_point_in_screen_ = gfx::Point();
 }
 
 void ShelfLayoutManager::CompleteAppListDrag(
@@ -2196,6 +2220,7 @@ void ShelfLayoutManager::CancelDrag() {
   }
   hotseat_is_in_drag_ = false;
   drag_status_ = kDragNone;
+  drag_start_point_in_screen_ = gfx::Point();
 }
 
 float ShelfLayoutManager::GetAppListBackgroundOpacityOnShelfOpacity() {

ash/shelf/shelf_layout_manager.h

@@ -610,6 +610,9 @@ class ASH_EXPORT ShelfLayoutManager : public AppListControllerObserver,
   // Location of the most recent mouse drag event in screen coordinate.
   gfx::Point last_mouse_drag_position_;
 
+  // Location of the beginning of a drag in screen coordinates.
+  gfx::Point drag_start_point_in_screen_;
+
   // When it is true, |CalculateAutoHideState| returns the current auto hide
   // state.
   bool is_auto_hide_state_locked_ = false;

ash/shelf/shelf_layout_manager_unittest.cc

@@ -3580,6 +3580,80 @@ TEST_P(HotseatShelfLayoutManagerTest, DragActiveWindowInTabletMode) {
   EXPECT_TRUE(window->layer()->transform().IsIdentity());
 }
 
+// Tests that swiping downward, towards the bezel, from a variety of points
+// results in hiding the hotseat.
+TEST_F(HotseatShelfLayoutManagerTest, HotseatHidesWhenSwipedToBezel) {
+  // Go to in-app shelf and extend the hotseat.
+  TabletModeControllerTestApi().EnterTabletMode();
+  std::unique_ptr<aura::Window> window =
+      AshTestBase::CreateTestWindow(gfx::Rect(0, 0, 400, 400));
+  wm::ActivateWindow(window.get());
+  SwipeUpOnShelf();
+
+  // Drag from the hotseat to the bezel, the hotseat should hide.
+  gfx::Rect shelf_widget_bounds = GetShelfWidget()->GetWindowBoundsInScreen();
+  gfx::Rect hotseat_bounds =
+      GetShelfWidget()->hotseat_widget()->GetWindowBoundsInScreen();
+  gfx::Point start = hotseat_bounds.top_center();
+  const gfx::Point end =
+      gfx::Point(shelf_widget_bounds.x() + shelf_widget_bounds.width() / 2,
+                 shelf_widget_bounds.bottom() + 1);
+  const base::TimeDelta kTimeDelta = base::TimeDelta::FromMilliseconds(100);
+  const int kNumScrollSteps = 4;
+  GetEventGenerator()->GestureScrollSequence(start, end, kTimeDelta,
+                                             kNumScrollSteps);
+
+  EXPECT_EQ(HotseatState::kHidden, GetShelfLayoutManager()->hotseat_state());
+
+  // Reset the hotseat and swipe from the center of the hotseat, it should hide.
+  SwipeUpOnShelf();
+
+  start = hotseat_bounds.CenterPoint();
+  GetEventGenerator()->GestureScrollSequence(start, end, kTimeDelta,
+                                             kNumScrollSteps);
+
+  EXPECT_EQ(HotseatState::kHidden, GetShelfLayoutManager()->hotseat_state());
+
+  // Reset the hotseat and swipe from the bottom of the hotseat, it should hide.
+  SwipeUpOnShelf();
+
+  start = hotseat_bounds.bottom_center();
+  start.Offset(0, -1);
+  GetEventGenerator()->GestureScrollSequence(start, end, kTimeDelta,
+                                             kNumScrollSteps);
+
+  EXPECT_EQ(HotseatState::kHidden, GetShelfLayoutManager()->hotseat_state());
+
+  // Reset the hotseat and swipe from the center of the in-app shelf, it should
+  // hide.
+  SwipeUpOnShelf();
+
+  start = shelf_widget_bounds.CenterPoint();
+
+  GetEventGenerator()->GestureScrollSequence(start, end, kTimeDelta,
+                                             kNumScrollSteps);
+
+  EXPECT_EQ(HotseatState::kHidden, GetShelfLayoutManager()->hotseat_state());
+
+  // Reset the hotseat and swipe from the bottom of the in-app shelf, it should
+  // hide.
+  SwipeUpOnShelf();
+
+  EXPECT_EQ(HotseatState::kExtended, GetShelfLayoutManager()->hotseat_state());
+  start = shelf_widget_bounds.bottom_center();
+  // The first few events which get sent to ShelfLayoutManager are
+  // ui::ET_TAP_DOWN, and ui::ET_GESTURE_START. After a few px we get
+  // ui::ET_GESTURE_SCROLL_UPDATE. Add 6 px of slop to get the first events out
+  // of the way, and 1 extra px to ensure we are not on the bottom edge of the
+  // display.
+  start.Offset(0, -7);
+
+  GetEventGenerator()->GestureScrollSequence(start, end, kTimeDelta,
+                                             kNumScrollSteps);
+
+  EXPECT_EQ(HotseatState::kHidden, GetShelfLayoutManager()->hotseat_state());
+}
+
 class ShelfLayoutManagerKeyboardTest : public AshTestBase {
  public:
   ShelfLayoutManagerKeyboardTest() = default;