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If the new fling is much slower (less than 1/5 of

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the previous fling), don't accelerate it.

Fix http://b/issue?id=2672074
This commit is contained in:
Grace Kloba
2010-05-17 19:19:06 -07:00
parent e0e9cb5434
commit 3c19d99042
1 changed files with 9 additions and 2 deletions
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11
core/java/android/webkit/WebView.java
View File

@@ -398,6 +398,10 @@ public class WebView extends AbsoluteLayout
private float mLastVelX;
private float mLastVelY;
// only trigger accelerated fling if the new velocity is at least
// MINIMUM_VELOCITY_RATIO_FOR_ACCELERATION times of the previous velocity
private static final float MINIMUM_VELOCITY_RATIO_FOR_ACCELERATION = 0.2f;
/**
* Touch mode
*/
@@ -5512,13 +5516,16 @@ public class WebView extends AbsoluteLayout
return;
}
float currentVelocity = mScroller.getCurrVelocity();
if (mLastVelocity > 0 && currentVelocity > 0) {
float velocity = (float) Math.hypot(vx, vy);
if (mLastVelocity > 0 && currentVelocity > 0 && velocity
> mLastVelocity * MINIMUM_VELOCITY_RATIO_FOR_ACCELERATION) {
float deltaR = (float) (Math.abs(Math.atan2(mLastVelY, mLastVelX)
- Math.atan2(vy, vx)));
final float circle = (float) (Math.PI) * 2.0f;
if (deltaR > circle * 0.9f || deltaR < circle * 0.1f) {
vx += currentVelocity * mLastVelX / mLastVelocity;
vy += currentVelocity * mLastVelY / mLastVelocity;
velocity = (float) Math.hypot(vx, vy);
if (DebugFlags.WEB_VIEW) {
Log.v(LOGTAG, "doFling vx= " + vx + " vy=" + vy);
}
@@ -5534,7 +5541,7 @@ public class WebView extends AbsoluteLayout
}
mLastVelX = vx;
mLastVelY = vy;
mLastVelocity = (float) Math.hypot(vx, vy);
mLastVelocity = velocity;
mScroller.fling(mScrollX, mScrollY, -vx, -vy, 0, maxX, 0, maxY);
// TODO: duration is calculated based on velocity, if the range is