overview gesture: adjust the fling event.

For a fling event, if the hotseat was hidden when the drag started,
only if the fling event position exceeds the restore-to-maximized
threshold, the window will be taken back to home screen.

Also, remove the logic to decide if drag can be allowed from
DragWindowFromShelfController as ShelfLayoutManager already handled it.

Bug: 997885
Change-Id: I35b9c35df1477b92b5c01db49c9302b6f3bace60
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1902176
Commit-Queue: Xiaoqian Dai <xdai@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#713677}

ash/home_screen/drag_window_from_shelf_controller.cc

@@ -46,6 +46,12 @@ constexpr float kMinimumWindowScaleDuringDragging = 0.2f;
 constexpr base::TimeDelta kShowOverviewTimeWhenDragSuspend =
     base::TimeDelta::FromMilliseconds(40);
 
+// The distance for the dragged window to pass over the bottom of the display
+// so that it can be dragged into home launcher or overview. If not pass this
+// value, the window will snap back to its original position.
+constexpr float kReturnToMaximizedDenseThreshold = 152.f;
+constexpr float kReturnToMaximizedStandardThreshold = 164.f;
+
 }  // namespace
 
 // Hide all visible windows expect the dragged windows or the window showing in
@@ -105,10 +111,20 @@ class DragWindowFromShelfController::WindowsHider
   DISALLOW_COPY_AND_ASSIGN(WindowsHider);
 };
 
+// static
+float DragWindowFromShelfController::GetReturnToMaximizedThreshold() {
+  return ShelfConfig::Get()->is_dense() ? kReturnToMaximizedDenseThreshold
+                                        : kReturnToMaximizedStandardThreshold;
+}
+
 DragWindowFromShelfController::DragWindowFromShelfController(
-    aura::Window* window)
-    : window_(window) {
+    aura::Window* window,
+    const gfx::Point& location_in_screen,
+    HotseatState hotseat_state)
+    : window_(window), hotseat_state_(hotseat_state) {
+  DCHECK_NE(hotseat_state, HotseatState::kShown);
   window_->AddObserver(this);
+  OnDragStarted(location_in_screen);
 }
 
 DragWindowFromShelfController::~DragWindowFromShelfController() {
@@ -124,17 +140,9 @@ void DragWindowFromShelfController::Drag(const gfx::Point& location_in_screen,
   if (!window_)
     return;
 
-  if (!drag_started_) {
-    // Do not start drag until the drag goes above the hotseat.
-    const gfx::Rect work_area =
-        screen_util::GetDisplayWorkAreaBoundsInScreenForActiveDeskContainer(
-            window_);
-    if (location_in_screen.y() >
-        work_area.bottom() - ShelfConfig::Get()->hotseat_size()) {
+  // TODO(xdai): clean up |drag_started_| variable.
+  if (!drag_started_)
     return;
-    }
-    OnDragStarted(location_in_screen);
-  }
 
   UpdateDraggedWindow(location_in_screen);
 
@@ -206,7 +214,7 @@ void DragWindowFromShelfController::EndDrag(
   const bool in_overview = overview_controller->InOverviewSession();
   const bool in_splitview = split_view_controller->InSplitViewMode();
 
-  if (ShouldGoToHomeScreen(velocity_y)) {
+  if (ShouldGoToHomeScreen(location_in_screen, velocity_y)) {
     DCHECK(!in_splitview);
     if (in_overview) {
       overview_controller->EndOverview(
@@ -397,7 +405,7 @@ SplitViewController::SnapPosition
 DragWindowFromShelfController::GetSnapPosition(
     const gfx::Point& location_in_screen) const {
   // if |location_in_screen| is close to the bottom of the screen and is
-  // inside of kReturnToMaximizedThreshold threshold, we should not try to
+  // inside of GetReturnToMaximizedThreshold() threshold, we should not try to
   // snap the window.
   if (ShouldRestoreToOriginalBounds(location_in_screen))
     return SplitViewController::NONE;
@@ -423,15 +431,25 @@ DragWindowFromShelfController::GetSnapPosition(
 
 bool DragWindowFromShelfController::ShouldRestoreToOriginalBounds(
     const gfx::Point& location_in_screen) const {
-  const gfx::Rect work_area = display::Screen::GetScreen()
+  const gfx::Rect display_bounds =
+      display::Screen::GetScreen()
           ->GetDisplayNearestPoint(location_in_screen)
-                                  .work_area();
+          .bounds();
   return location_in_screen.y() >
-         work_area.bottom() - kReturnToMaximizedThreshold;
+         display_bounds.bottom() - GetReturnToMaximizedThreshold();
 }
 
 bool DragWindowFromShelfController::ShouldGoToHomeScreen(
+    const gfx::Point& location_in_screen,
     base::Optional<float> velocity_y) const {
+  // For a hidden hotseat, if the event end position does not exceed
+  // GetReturnToMaximizedThreshold(), it should restore back to the maximized
+  // bounds even though the velocity might be large.
+  if (hotseat_state_ == HotseatState::kHidden &&
+      ShouldRestoreToOriginalBounds(location_in_screen)) {
+    return false;
+  }
+
   return velocity_y.has_value() && *velocity_y < 0 &&
          std::abs(*velocity_y) >= kVelocityToHomeScreenThreshold &&
          !SplitViewController::Get(Shell::GetPrimaryRootWindow())
@@ -443,7 +461,7 @@ DragWindowFromShelfController::GetSnapPositionOnDragEnd(
     const gfx::Point& location_in_screen,
     base::Optional<float> velocity_y) const {
   if (ShouldRestoreToOriginalBounds(location_in_screen) ||
-      ShouldGoToHomeScreen(velocity_y)) {
+      ShouldGoToHomeScreen(location_in_screen, velocity_y)) {
     return SplitViewController::NONE;
   }
 
@@ -456,7 +474,7 @@ bool DragWindowFromShelfController::ShouldDropWindowInOverview(
   if (!Shell::Get()->overview_controller()->InOverviewSession())
     return false;
 
-  if (ShouldGoToHomeScreen(velocity_y))
+  if (ShouldGoToHomeScreen(location_in_screen, velocity_y))
     return false;
 
   const bool in_splitview =

ash/home_screen/drag_window_from_shelf_controller.h

@@ -8,6 +8,7 @@
 #include <vector>
 
 #include "ash/ash_export.h"
+#include "ash/public/cpp/shelf_types.h"
 #include "ash/public/cpp/window_properties.h"
 #include "ash/wm/splitview/split_view_controller.h"
 #include "base/macros.h"
@@ -26,11 +27,6 @@ namespace ash {
 // swiping up from the shelf to homescreen, overview or splitview.
 class ASH_EXPORT DragWindowFromShelfController : public aura::WindowObserver {
  public:
-  // The distance for the dragged window to pass over shelf so that it can be
-  // dragged into home launcher or overview. If not pass this value, the window
-  // will snap back to its original position.
-  static constexpr float kReturnToMaximizedThreshold = 116;
-
   // The deceleration threshold to open overview behind the dragged window
   // when swiping up from the shelf to drag the active window.
   static constexpr float kOpenOverviewThreshold = 10.f;
@@ -47,7 +43,15 @@ class ASH_EXPORT DragWindowFromShelfController : public aura::WindowObserver {
   // view is active during dragging.
   static constexpr float kVelocityToOverviewThreshold = 1000.f;
 
-  explicit DragWindowFromShelfController(aura::Window* window);
+  // The distance for the dragged window to pass over the bottom of the display
+  // so that it can be dragged into home launcher or overview. If not pass this
+  // value, the window will snap back to its original position. The value is
+  // different for standard or dense shelf.
+  static float GetReturnToMaximizedThreshold();
+
+  DragWindowFromShelfController(aura::Window* window,
+                                const gfx::Point& location_in_screen,
+                                HotseatState hotseat_state);
   ~DragWindowFromShelfController() override;
 
   // Called during swiping up on the shelf.
@@ -81,7 +85,7 @@ class ASH_EXPORT DragWindowFromShelfController : public aura::WindowObserver {
 
   // Returns true if the dragged window should restore to its original bounds
   // after drag ends. Happens when |location_in_screen| is within
-  // kReturnToMaximizedThreshold threshold.
+  // GetReturnToMaximizedThreshold() threshold.
   bool ShouldRestoreToOriginalBounds(
       const gfx::Point& location_in_screen) const;
 
@@ -89,7 +93,8 @@ class ASH_EXPORT DragWindowFromShelfController : public aura::WindowObserver {
   // the upward vertical velocity is larger than kVelocityToHomeScreenThreshold
   // and splitview is not active. Note when splitview is active, we do not allow
   // to go to home screen by fling.
-  bool ShouldGoToHomeScreen(base::Optional<float> velocity_y) const;
+  bool ShouldGoToHomeScreen(const gfx::Point& location_in_screen,
+                            base::Optional<float> velocity_y) const;
 
   // Returns the desired snap position on |location_in_screen| when drag ends.
   SplitViewController::SnapPosition GetSnapPositionOnDragEnd(
@@ -125,6 +130,9 @@ class ASH_EXPORT DragWindowFromShelfController : public aura::WindowObserver {
   // Timer to show and update overview.
   base::OneShotTimer show_overview_timer_;
 
+  // The hotseat state when drag starts.
+  const HotseatState hotseat_state_;
+
   DISALLOW_COPY_AND_ASSIGN(DragWindowFromShelfController);
 };
 

ash/public/cpp/shelf_config.h

@@ -141,6 +141,8 @@ class ASH_EXPORT ShelfConfig : public TabletModeObserver,
     return mousewheel_scroll_offset_threshold_;
   }
 
+  bool is_dense() const { return is_dense_; }
+
   // Gets the current color for the shelf control buttons.
   SkColor GetShelfControlButtonColor() const;
 

ash/shelf/shelf_layout_manager.cc

@@ -2456,8 +2456,8 @@ bool ShelfLayoutManager::MaybeStartDragWindowFromShelf(
   if (!window)
     return false;
 
-  window_drag_controller_ =
-      std::make_unique<DragWindowFromShelfController>(window);
+  window_drag_controller_ = std::make_unique<DragWindowFromShelfController>(
+      window, event_in_screen.location(), hotseat_state());
   return true;
 }