Changeset 285964 in webkit

Timestamp:

Nov 17, 2021, 3:55:47 PM (5 years ago)

Author:

timothy_horton@apple.com

Message:

Momentum animator: Short scrolls are too far, medium scrolls aren't far enough
​https://bugs.webkit.org/show_bug.cgi?id=233272
<rdar://problem/85472653>

Reviewed by Simon Fraser.

• platform/mac/ScrollingEffectsController.mm:

(WebCore::adjustedVelocity):
(WebCore::ScrollingEffectsController::handleWheelEvent):
Attempt to apply a empirically-derived curve to the initial velocity
to fit the distance of a normal momentum scroll.

Location:

trunk/Source/WebCore

Files:

• ChangeLog (modified) (1 diff)
• platform/mac/ScrollingEffectsController.mm (modified) (2 diffs)

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2021-11-17  Tim Horton  <timothy_horton@apple.com>
+
+        Momentum animator: Short scrolls are too far, medium scrolls aren't far enough
+        https://bugs.webkit.org/show_bug.cgi?id=233272
+        <rdar://problem/85472653>
+
+        Reviewed by Simon Fraser.
+
+        * platform/mac/ScrollingEffectsController.mm:
+        (WebCore::adjustedVelocity):
+        (WebCore::ScrollingEffectsController::handleWheelEvent):
+        Attempt to apply a empirically-derived curve to the initial velocity
+        to fit the distance of a normal momentum scroll.
+
 2021-11-17  Alan Bujtas  <zalan@apple.com>
 

trunk/Source/WebCore/platform/mac/ScrollingEffectsController.mm

@@ -128 +128 @@
 #endif
 
+static FloatSize adjustedVelocity(FloatSize velocity)
+{
+    auto applyCurve = ^(float originalValue) {
+        if (!originalValue)
+            return originalValue;
+
+        float value = fabs(originalValue);
+        float powerLow = 6.7 * pow(value, -.166);
+        float powerHigh = 36.3 * pow(value, -.392);
+        const float transitionVelocity = 2000;
+
+        auto interpolate = ^(float v0, float v1, float t) {
+            return (1 - t) * v0 + t * v1;
+        };
+        
+        float multiplier = interpolate(powerLow, powerHigh, std::min(value, transitionVelocity) / transitionVelocity);
+        return copysign(value * multiplier, originalValue);
+    };
+
+    return { applyCurve(velocity.width()), applyCurve(velocity.height()) };
+}
+
 bool ScrollingEffectsController::handleWheelEvent(const PlatformWheelEvent& wheelEvent)
 {
@@ -226 +248 @@
         m_momentumScrollInProgress = true;
         if (momentumScrollingAnimatorEnabled()) {
-            startMomentumScrollWithInitialVelocity(m_client.scrollOffset(), -wheelEvent.scrollingVelocity(), -wheelEvent.delta(), [](const FloatPoint& targetOffset) { return targetOffset; });
+            startMomentumScrollWithInitialVelocity(m_client.scrollOffset(), -adjustedVelocity(wheelEvent.scrollingVelocity()), -wheelEvent.delta(), [](const FloatPoint& targetOffset) { return targetOffset; });
 #if !LOG_DISABLED
             m_eventDrivenScrollOffset = m_client.scrollOffset();