back nudge: dismiss the back nudge when the user performs back from edge.

Bug: 1061144
Change-Id: I9f84dd6a381fb32624826f58a24e6aca8a2059a3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2108089
Commit-Queue: Xiaoqian Dai <xdai@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#751499}

ash/wm/gestures/back_gesture/back_gesture_contextual_nudge.cc

@@ -66,6 +66,16 @@ constexpr base::TimeDelta kNudgeShowAnimationDuration =
 constexpr base::TimeDelta kNudgeHideAnimationDuration =
     base::TimeDelta::FromMilliseconds(400);
 
+// Duration for the animation to fade out the suggestion label and circle when
+// the back nudge showing animation is interrupted and should be dismissed.
+constexpr base::TimeDelta kSuggestionDismissDuration =
+    base::TimeDelta::FromMilliseconds(100);
+
+// Duration for the animation to fade out the gradient layer when the back nudge
+// showing animation is interrupted and should be dismissed.
+constexpr base::TimeDelta kDarkGradientDismissDuration =
+    base::TimeDelta::FromMilliseconds(200);
+
 // Duration for the animation of the suggestion part of the nudge.
 constexpr base::TimeDelta kSuggestionBounceAnimationDuration =
     base::TimeDelta::FromMilliseconds(600);
@@ -109,6 +119,7 @@ class BackGestureContextualNudge::ContextualNudgeView
     SetPaintToLayer();
     layer()->SetFillsBoundsOpaquely(false);
 
+    gradient_view_ = AddChildView(std::make_unique<GradientView>(this));
     suggestion_view_ = AddChildView(std::make_unique<SuggestionView>(this));
 
     show_timer_.Start(
@@ -141,13 +152,8 @@ class BackGestureContextualNudge::ContextualNudgeView
       suggestion_view_->layer()->GetAnimator()->AbortAllAnimations();
 
       animation_stage_ = AnimationStage::kFadingOut;
-      ui::ScopedLayerAnimationSettings animation(layer()->GetAnimator());
-      animation.SetTransitionDuration(kNudgeHideAnimationDuration);
-      animation.SetTweenType(gfx::Tween::FAST_OUT_LINEAR_IN);
-      animation.SetPreemptionStrategy(
-          ui::LayerAnimator::IMMEDIATELY_ANIMATE_TO_NEW_TARGET);
-      animation.AddObserver(this);
-      layer()->SetOpacity(0.f);
+      gradient_view_->FadeOutForDismiss();
+      suggestion_view_->FadeOutForDismiss();
     }
   }
 
@@ -211,6 +217,17 @@ class BackGestureContextualNudge::ContextualNudgeView
       layer()->SetTransform(transform);
     }
 
+    // Called when the in-progress animation is cancelled. The suggestion view
+    // will fade out.
+    void FadeOutForDismiss() {
+      ui::ScopedLayerAnimationSettings animation(layer()->GetAnimator());
+      animation.SetTransitionDuration(kSuggestionDismissDuration);
+      animation.SetTweenType(gfx::Tween::LINEAR);
+      animation.SetPreemptionStrategy(
+          ui::LayerAnimator::IMMEDIATELY_ANIMATE_TO_NEW_TARGET);
+      layer()->SetOpacity(0.f);
+    }
+
    private:
     // views::View:
     void Layout() override {
@@ -254,6 +271,48 @@ class BackGestureContextualNudge::ContextualNudgeView
     ContextualNudgeView* nudge_view_ = nullptr;  // Not owned.
   };
 
+  // Used to show the gradient layer of the back gesture contextual nudge.
+  class GradientView : public views::View {
+   public:
+    explicit GradientView(ContextualNudgeView* nudge_view)
+        : nudge_view_(nudge_view) {
+      SetPaintToLayer();
+      layer()->SetFillsBoundsOpaquely(false);
+    }
+    GradientView(const GradientView&) = delete;
+    GradientView& operator=(const GradientView&) = delete;
+    ~GradientView() override = default;
+
+    // This is called when the nudge animation is cancelled. The gradient
+    // view will fade out.
+    void FadeOutForDismiss() {
+      ui::ScopedLayerAnimationSettings animation(layer()->GetAnimator());
+      animation.SetTransitionDuration(kDarkGradientDismissDuration);
+      animation.SetTweenType(gfx::Tween::LINEAR);
+      animation.SetPreemptionStrategy(
+          ui::LayerAnimator::IMMEDIATELY_ANIMATE_TO_NEW_TARGET);
+      animation.AddObserver(nudge_view_);
+      layer()->SetOpacity(0.f);
+    }
+
+    // views::View:
+    void OnPaint(gfx::Canvas* canvas) override {
+      views::View::OnPaint(canvas);
+
+      // Draw the gradient background.
+      cc::PaintFlags flags;
+      flags.setAntiAlias(true);
+      flags.setStyle(cc::PaintFlags::kFill_Style);
+      flags.setShader(gfx::CreateGradientShader(
+          gfx::Point(), gfx::Point(width(), 0), kBackgroundStartColor,
+          kBackgroundEndColor));
+      canvas->DrawRect(gfx::Rect(size()), flags);
+    }
+
+   private:
+    ContextualNudgeView* nudge_view_ = nullptr;  // Not owned
+  };
+
   // Showing contextual nudge from off screen to its start position.
   void ScheduleOffScreenToStartPositionAnimation() {
     animation_stage_ = AnimationStage::kSlidingIn;
@@ -281,25 +340,13 @@ class BackGestureContextualNudge::ContextualNudgeView
   // views::View:
   void Layout() override {
     gfx::Rect rect = GetLocalBounds();
+    gradient_view_->SetBoundsRect(rect);
+
     rect.ClampToCenteredSize(gfx::Size(kBackgroundWidth, kBackgroundWidth));
     rect.set_x(-kCircleRadius);
     suggestion_view_->SetBoundsRect(rect);
   }
 
-  // views::View:
-  void OnPaint(gfx::Canvas* canvas) override {
-    views::View::OnPaint(canvas);
-
-    // Draw the gradient background.
-    cc::PaintFlags flags;
-    flags.setAntiAlias(true);
-    flags.setStyle(cc::PaintFlags::kFill_Style);
-    flags.setShader(
-        gfx::CreateGradientShader(gfx::Point(), gfx::Point(width(), 0),
-                                  kBackgroundStartColor, kBackgroundEndColor));
-    canvas->DrawRect(gfx::Rect(size()), flags);
-  }
-
   // ui::ImplicitAnimationObserver:
   void OnImplicitAnimationsCompleted() override {
     if (animation_stage_ == AnimationStage::kFadingOut ||
@@ -318,6 +365,9 @@ class BackGestureContextualNudge::ContextualNudgeView
     }
   }
 
+  // Owned by views hierarchy.
+  GradientView* gradient_view_ = nullptr;
+
   // Created by ContextualNudgeView. Owned by views hierarchy.
   SuggestionView* suggestion_view_ = nullptr;
 

ash/wm/gestures/back_gesture/back_gesture_contextual_nudge_controller_impl.cc

@@ -35,6 +35,11 @@ BackGestureContextualNudgeControllerImpl::
   DoCleanUp();
 }
 
+void BackGestureContextualNudgeControllerImpl::OnBackGestureStarted() {
+  if (nudge_)
+    nudge_->CancelAnimationOrFadeOutToHide();
+}
+
 void BackGestureContextualNudgeControllerImpl::OnActiveUserSessionChanged(
     const AccountId& account_id) {
   UpdateWindowMonitoring(/*can_show_nudge_immediately=*/true);

ash/wm/gestures/back_gesture/back_gesture_contextual_nudge_controller_impl.h

@@ -39,6 +39,10 @@ class ASH_EXPORT BackGestureContextualNudgeControllerImpl
 
   ~BackGestureContextualNudgeControllerImpl() override;
 
+  // Calls when the user starts perform back gesture. We'll cancel the animation
+  // if the back nudge is waiting to be shown or is showing.
+  void OnBackGestureStarted();
+
   // SessionObserver:
   void OnActiveUserSessionChanged(const AccountId& account_id) override;
   void OnSessionStateChanged(session_manager::SessionState state) override;

ash/wm/gestures/back_gesture/back_gesture_event_handler.cc

@@ -227,6 +227,10 @@ bool BackGestureEventHandler::MaybeHandleBackGesture(ui::GestureEvent* event,
         break;
       back_gesture_affordance_ = std::make_unique<BackGestureAffordance>(
           screen_location, dragged_from_splitview_divider_);
+      if (features::AreContextualNudgesEnabled()) {
+        // Cancel the in-waiting or in-progress back nudge animation.
+        nudge_controller_->OnBackGestureStarted();
+      }
       return true;
     case ui::ET_GESTURE_SCROLL_BEGIN:
       if (!going_back_started_)