Changeset 188641 in webkit

Timestamp:

Aug 19, 2015 11:13:53 AM (9 years ago)

Author:

Wenson Hsieh

Message:

Scroll snapping should trigger when receiving a momentum end wheel event
​https://bugs.webkit.org/show_bug.cgi?id=148155

Reviewed by Alexey Proskuryakov.

No new tests, since the purpose of this patch is to get existing tests to pass when
allowing similar wheel events to coalesce. To accomplish this, we relax our assumption
that the user must have generated at least 3 momentum wheel events in order for the
gliding animation to trigger. Upon receiving a wheel event indicating the end of the
momentum phase, we now kick off the gliding animation as long as any momentum event
was tracked earlier in the gesture with a nonzero wheel delta.

• platform/cocoa/ScrollController.mm:

(WebCore::ScrollController::processWheelEventForScrollSnapOnAxis): Added logic to

begin a glide animation if we have received a momentum end event but have not
yet triggered a gliding animation.

• platform/cocoa/ScrollSnapAnimatorState.h:
• platform/cocoa/ScrollSnapAnimatorState.mm:

(WebCore::ScrollSnapAnimatorState::wheelDeltaTrackingIsInProgress): Minor refactoring

to make the wheel event processing code more readable.

(WebCore::ScrollSnapAnimatorState::hasFinishedTrackingWheelDeltas): Ditto.

Location:

trunk/Source/WebCore

Files:

• ChangeLog (modified) (1 diff)
• platform/cocoa/ScrollController.mm (modified) (2 diffs)
• platform/cocoa/ScrollSnapAnimatorState.h (modified) (1 diff)
• platform/cocoa/ScrollSnapAnimatorState.mm (modified) (1 diff)

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2015-08-18  Wenson Hsieh  <wenson_hsieh@apple.com>
+
+        Scroll snapping should trigger when receiving a momentum end wheel event
+        https://bugs.webkit.org/show_bug.cgi?id=148155
+
+        Reviewed by Alexey Proskuryakov.
+
+        No new tests, since the purpose of this patch is to get existing tests to pass when
+        allowing similar wheel events to coalesce. To accomplish this, we relax our assumption
+        that the user must have generated at least 3 momentum wheel events in order for the
+        gliding animation to trigger. Upon receiving a wheel event indicating the end of the
+        momentum phase, we now kick off the gliding animation as long as any momentum event
+        was tracked earlier in the gesture with a nonzero wheel delta.
+
+        * platform/cocoa/ScrollController.mm:
+        (WebCore::ScrollController::processWheelEventForScrollSnapOnAxis): Added logic to
+            begin a glide animation if we have received a momentum end event but have not
+            yet triggered a gliding animation.
+        * platform/cocoa/ScrollSnapAnimatorState.h:
+        * platform/cocoa/ScrollSnapAnimatorState.mm:
+        (WebCore::ScrollSnapAnimatorState::wheelDeltaTrackingIsInProgress): Minor refactoring
+            to make the wheel event processing code more readable.
+        (WebCore::ScrollSnapAnimatorState::hasFinishedTrackingWheelDeltas): Ditto.
+
 2015-08-18  Myles C. Maxfield  <mmaxfield@apple.com>
 

trunk/Source/WebCore/platform/cocoa/ScrollController.mm

@@ -555 +555 @@
         // This check for DestinationReached ensures that we don't receive another set of momentum events after ending the last glide.
         if (snapState.m_currentState != ScrollSnapState::Gliding && snapState.m_currentState != ScrollSnapState::DestinationReached) {
-            if (snapState.m_numWheelDeltasTracked < snapState.wheelDeltaWindowSize && wheelDelta)
+            if (snapState.wheelDeltaTrackingIsInProgress() && wheelDelta)
                 snapState.pushInitialWheelDelta(wheelDelta);
             
-            if ((snapState.m_numWheelDeltasTracked == snapState.wheelDeltaWindowSize) && snapState.averageInitialWheelDelta())
+            if (snapState.hasFinishedTrackingWheelDeltas() && snapState.averageInitialWheelDelta())
                 beginScrollSnapAnimation(axis, ScrollSnapState::Gliding);
         }
@@ -564 +564 @@
         
     case WheelEventStatus::InertialScrollEnd:
+        if (snapState.wheelDeltaTrackingIsInProgress() && snapState.averageInitialWheelDelta())
+            beginScrollSnapAnimation(axis, ScrollSnapState::Gliding);
+
         snapState.clearInitialWheelDeltaWindow();
         snapState.m_shouldOverrideWheelEvent = false;

trunk/Source/WebCore/platform/cocoa/ScrollSnapAnimatorState.h

@@ -53 +53 @@
     bool isSnapping() const;
     bool canReachTargetWithCurrentInitialScrollDelta() const;
+    bool wheelDeltaTrackingIsInProgress() const;
+    bool hasFinishedTrackingWheelDeltas() const;
     float interpolatedOffsetAtProgress(float) const;
     

trunk/Source/WebCore/platform/cocoa/ScrollSnapAnimatorState.mm

@@ -85 +85 @@
 }
     
+bool ScrollSnapAnimatorState::wheelDeltaTrackingIsInProgress() const
+{
+    return m_numWheelDeltasTracked && m_numWheelDeltasTracked < wheelDeltaWindowSize;
+}
+
+bool ScrollSnapAnimatorState::hasFinishedTrackingWheelDeltas() const
+{
+    return m_numWheelDeltasTracked == wheelDeltaWindowSize;
+}
+
 float ScrollSnapAnimatorState::interpolatedOffsetAtProgress(float progress) const
 {