gestures: Generate only either scroll-end or fling-start events at the end of a scroll gesture.

When a fling happens at the end of a scroll, instead of generating both a scroll-end
and a fling-start event, generate only fling-start event. Unfortunately, WebKit still
requires an explicit scroll-end gesture before a fling, so continue to do that as a
special case.

BUG=141460,141309

Review URL: https://chromiumcodereview.appspot.com/10826209

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@150852 0039d316-1c4b-4281-b951-d872f2087c98

8 files changed, 57 insertions, 41 deletions

diff --git a/ash/wm/toplevel_window_event_filter.cc b/ash/wm/toplevel_window_event_filter.cc
index 1f669a5..e896d07 100644
--- a/ash/wm/toplevel_window_event_filter.cc
+++ b/ash/wm/toplevel_window_event_filter.cc
@@ -149,17 +149,22 @@ ui::GestureStatus ToplevelWindowEventFilter::PreHandleGestureEvent(
       break;
     }
     case ui::ET_GESTURE_SCROLL_END:
-      if (!in_gesture_resize_)
-        return ui::GESTURE_STATUS_UNKNOWN;
-      CompleteDrag(DRAG_COMPLETE, event->flags());
-      if (in_move_loop_) {
-        quit_closure_.Run();
-        in_move_loop_ = false;
+    case ui::ET_SCROLL_FLING_START: {
+      ui::GestureStatus status = ui::GESTURE_STATUS_UNKNOWN;
+      if (in_gesture_resize_) {
+        // If the window was being resized, then just complete the resize.
+        CompleteDrag(DRAG_COMPLETE, event->flags());
+        if (in_move_loop_) {
+          quit_closure_.Run();
+          in_move_loop_ = false;
+        }
+        in_gesture_resize_ = false;
+        status = ui::GESTURE_STATUS_CONSUMED;
       }
-      in_gesture_resize_ = false;
-      break;
 
-    case ui::ET_SCROLL_FLING_START: {
+      if (event->type() == ui::ET_GESTURE_SCROLL_END)
+        return status;
+
       int component =
           target->delegate()->GetNonClientComponent(event->location());
       if (WindowResizer::GetBoundsChangeForWindowComponent(component) == 0)
diff --git a/ui/app_list/contents_view.cc b/ui/app_list/contents_view.cc
index 4b4bc77..2ad9887 100644
--- a/ui/app_list/contents_view.cc
+++ b/ui/app_list/contents_view.cc
@@ -204,13 +204,14 @@ ui::GestureStatus ContentsView::OnGestureEvent(
       pagination_model_->EndScroll();
       return ui::GESTURE_STATUS_CONSUMED;
     case ui::ET_SCROLL_FLING_START: {
+      pagination_model_->EndScroll();
       if (fabs(event.details().velocity_x()) > kMinHorizVelocityToSwitchPage) {
+        pagination_model_->ResetTransitionAnimation();
         pagination_model_->SelectPageRelative(
             event.details().velocity_x() < 0 ? 1 : -1,
             true);
-        return ui::GESTURE_STATUS_CONSUMED;
       }
-      break;
+      return ui::GESTURE_STATUS_CONSUMED;
     }
     default:
       break;
diff --git a/ui/app_list/pagination_model.cc b/ui/app_list/pagination_model.cc
index cc9e402..97ba5e8 100644
--- a/ui/app_list/pagination_model.cc
+++ b/ui/app_list/pagination_model.cc
@@ -56,7 +56,7 @@ void PaginationModel::SelectPage(int page, bool animate) {
     if (page == selected_page_)
       return;
 
-    ResetTranstionAnimation();
+    ResetTransitionAnimation();
 
     int old_selected = selected_page_;
     selected_page_ = page;
@@ -86,6 +86,13 @@ void PaginationModel::SetTransitionDuration(int duration_ms) {
   transition_duration_ms_ = duration_ms;
 }
 
+void PaginationModel::ResetTransitionAnimation() {
+  transition_animation_.reset();
+  transition_.target_page = -1;
+  transition_.progress = 0;
+  pending_selected_page_ = -1;
+}
+
 void PaginationModel::StartScroll() {
   // Cancels current transition animation (if any).
   transition_animation_.reset();
@@ -185,13 +192,6 @@ void PaginationModel::CreateTransitionAnimation() {
     transition_animation_->SetSlideDuration(transition_duration_ms_);
 }
 
-void PaginationModel::ResetTranstionAnimation() {
-  transition_animation_.reset();
-  transition_.target_page = -1;
-  transition_.progress = 0;
-  pending_selected_page_ = -1;
-}
-
 void PaginationModel::AnimationProgressed(const ui::Animation* animation) {
   transition_.progress = transition_animation_->GetCurrentValue();
   NotifyTransitionChanged();
@@ -216,7 +216,7 @@ void PaginationModel::AnimationEnded(const ui::Animation* animation) {
     SelectPage(transition_.target_page, false /* animate */);
   } else if (transition_animation_->GetCurrentValue() == 0) {
     // Hiding animation ends. No page change should happen.
-    ResetTranstionAnimation();
+    ResetTransitionAnimation();
   }
 
   if (next_target >= 0)
diff --git a/ui/app_list/pagination_model.h b/ui/app_list/pagination_model.h
index abf2100..39f88e0 100644
--- a/ui/app_list/pagination_model.h
+++ b/ui/app_list/pagination_model.h
@@ -60,6 +60,7 @@ class APP_LIST_EXPORT PaginationModel : public ui::AnimationDelegate {
 
   void SetTransition(const Transition& transition);
   void SetTransitionDuration(int duration_ms);
+  void ResetTransitionAnimation();
 
   // Starts a scroll transition. If there is a running transition animation,
   // cancels it but keeps the transition info.
@@ -107,7 +108,6 @@ class APP_LIST_EXPORT PaginationModel : public ui::AnimationDelegate {
 
   void StartTranstionAnimation(int target_page);
   void CreateTransitionAnimation();
-  void ResetTranstionAnimation();
 
   // ui::AnimationDelegate overrides:
   virtual void AnimationProgressed(const ui::Animation* animation) OVERRIDE;
diff --git a/ui/aura/gestures/gesture_recognizer_unittest.cc b/ui/aura/gestures/gesture_recognizer_unittest.cc
index 00d1302..4391fe7 100644
--- a/ui/aura/gestures/gesture_recognizer_unittest.cc
+++ b/ui/aura/gestures/gesture_recognizer_unittest.cc
@@ -164,8 +164,10 @@ class GestureEventConsumeDelegate : public TestWindowDelegate {
       case ui::ET_SCROLL_FLING_START:
         EXPECT_TRUE(gesture->details().velocity_x() != 0 ||
                     gesture->details().velocity_y() != 0);
-        EXPECT_TRUE(scroll_end_);
+        EXPECT_FALSE(scroll_end_);
         fling_ = true;
+        velocity_x_ = gesture->details().velocity_x();
+        velocity_y_ = gesture->details().velocity_y();
         break;
       case ui::ET_GESTURE_TWO_FINGER_TAP:
         two_finger_tap_ = true;
@@ -859,8 +861,9 @@ TEST_F(GestureRecognizerTest, GestureEventHorizontalRailFling) {
                              kTouchId, GetTime());
   root_window()->AsRootWindowHostDelegate()->OnHostTouchEvent(&release);
 
-  EXPECT_TRUE(delegate->scroll_end());
-  EXPECT_EQ(0, delegate->velocity_x());
+  EXPECT_TRUE(delegate->fling());
+  EXPECT_FALSE(delegate->scroll_end());
+  EXPECT_GT(delegate->velocity_x(), 0);
   EXPECT_EQ(0, delegate->velocity_y());
 }
 
@@ -895,9 +898,10 @@ TEST_F(GestureRecognizerTest, GestureEventVerticalRailFling) {
                              kTouchId, GetTime());
   root_window()->AsRootWindowHostDelegate()->OnHostTouchEvent(&release);
 
-  EXPECT_TRUE(delegate->scroll_end());
+  EXPECT_TRUE(delegate->fling());
+  EXPECT_FALSE(delegate->scroll_end());
   EXPECT_EQ(0, delegate->velocity_x());
-  EXPECT_EQ(0, delegate->velocity_y());
+  EXPECT_GT(delegate->velocity_y(), 0);
 }
 
 // Check Scroll End Events reports zero velocities
@@ -929,9 +933,10 @@ TEST_F(GestureRecognizerTest, GestureEventNonRailFling) {
                              kTouchId, GetTime());
   root_window()->AsRootWindowHostDelegate()->OnHostTouchEvent(&release);
 
-  EXPECT_TRUE(delegate->scroll_end());
-  EXPECT_EQ(0, delegate->velocity_x());
-  EXPECT_EQ(0, delegate->velocity_y());
+  EXPECT_TRUE(delegate->fling());
+  EXPECT_FALSE(delegate->scroll_end());
+  EXPECT_GT(delegate->velocity_x(), 0);
+  EXPECT_GT(delegate->velocity_y(), 0);
 }
 
 // Check that appropriate touch events generate long press events
diff --git a/ui/base/gestures/gesture_sequence.cc b/ui/base/gestures/gesture_sequence.cc
index b52babb..2f9b1546 100644
--- a/ui/base/gestures/gesture_sequence.cc
+++ b/ui/base/gestures/gesture_sequence.cc
@@ -642,15 +642,6 @@ void GestureSequence::AppendScrollGestureEnd(const GesturePoint& point,
   else if (scroll_type_ == ST_VERTICAL)
     railed_x_velocity = 0;
 
-  // TODO(rjkroege): It is conceivable that we could suppress sending the
-  // GestureScrollEnd if it is immediately followed by a GestureFlingStart.
-  gestures->push_back(CreateGestureEvent(
-      GestureEventDetails(ui::ET_GESTURE_SCROLL_END, 0, 0),
-      location,
-      flags_,
-      base::Time::FromDoubleT(point.last_touch_time()),
-      1 << point.touch_id()));
-
   if (railed_x_velocity != 0 || railed_y_velocity != 0) {
     // TODO(sad|rjkroege): fling-curve is currently configured to work well with
     // touchpad scroll-events. This curve needs to be adjusted to work correctly
@@ -666,6 +657,13 @@ void GestureSequence::AppendScrollGestureEnd(const GesturePoint& point,
         flags_,
         base::Time::FromDoubleT(point.last_touch_time()),
         1 << point.touch_id()));
+  } else {
+    gestures->push_back(CreateGestureEvent(
+        GestureEventDetails(ui::ET_GESTURE_SCROLL_END, 0, 0),
+        location,
+        flags_,
+        base::Time::FromDoubleT(point.last_touch_time()),
+        1 << point.touch_id()));
   }
 }
 
diff --git a/ui/views/events/event.h b/ui/views/events/event.h
index 1a518d3..931441d8 100644
--- a/ui/views/events/event.h
+++ b/ui/views/events/event.h
@@ -91,6 +91,11 @@ class VIEWS_EXPORT Event {
            type_ == ui::ET_GESTURE_SCROLL_END;
   }
 
+  bool IsFlingScrollEvent() const {
+    return type_ == ui::ET_SCROLL_FLING_CANCEL ||
+           type_ == ui::ET_SCROLL_FLING_START;
+  }
+
  protected:
   Event(ui::EventType type, int flags);
   Event(const NativeEvent& native_event, ui::EventType type, int flags);
diff --git a/ui/views/widget/root_view.cc b/ui/views/widget/root_view.cc
index 2e799a8..c5a72e4 100644
--- a/ui/views/widget/root_view.cc
+++ b/ui/views/widget/root_view.cc
@@ -458,8 +458,9 @@ ui::GestureStatus RootView::OnGestureEvent(const GestureEvent& event) {
   if (gesture_handler_) {
     // |gesture_handler_| (or |scroll_gesture_handler_|) can be deleted during
     // processing.
-    View* handler = event.IsScrollGestureEvent() && scroll_gesture_handler_ ?
-        scroll_gesture_handler_ : gesture_handler_;
+    View* handler = scroll_gesture_handler_ &&
+        (event.IsScrollGestureEvent() || event.IsFlingScrollEvent())  ?
+            scroll_gesture_handler_ : gesture_handler_;
     GestureEvent handler_event(event, this, handler);
 
     ui::GestureStatus status = handler->ProcessGestureEvent(handler_event);
@@ -468,7 +469,8 @@ ui::GestureStatus RootView::OnGestureEvent(const GestureEvent& event) {
         event.details().touch_points() <= 1)
       gesture_handler_ = NULL;
 
-    if (event.type() == ui::ET_GESTURE_SCROLL_END && scroll_gesture_handler_)
+    if (scroll_gesture_handler_ && (event.type() == ui::ET_GESTURE_SCROLL_END ||
+                                    event.type() == ui::ET_SCROLL_FLING_START))
       scroll_gesture_handler_ = NULL;
 
     if (status == ui::GESTURE_STATUS_CONSUMED)