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Merge "Fix huge bounce-back in ListView when double-flinging" into mnc-dev

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This commit is contained in:
Vladislav Kaznacheev
2015-06-22 09:30:17 +00:00
committed by Android (Google) Code Review
parent c28695079e 160d12ee51
commit 8228e4247c
1 changed files with 8 additions and 4 deletions
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12
core/java/android/widget/OverScroller.java
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@@ -731,7 +731,7 @@ public class OverScroller {
// mStartTime has been set
mFinished = false;
mState = CUBIC;
mStart = start;
mCurrentPosition = mStart = start;
mFinal = end;
final int delta = start - end;
mDeceleration = getDeceleration(delta);
@@ -797,7 +797,9 @@ public class OverScroller {
private void fitOnBounceCurve(int start, int end, int velocity) {
// Simulate a bounce that started from edge
final float durationToApex = - velocity / mDeceleration;
final float distanceToApex = velocity * velocity / 2.0f / Math.abs(mDeceleration);
// The float cast below is necessary to avoid integer overflow.
final float velocitySquared = (float) velocity * velocity;
final float distanceToApex = velocitySquared / 2.0f / Math.abs(mDeceleration);
final float distanceToEdge = Math.abs(end - start);
final float totalDuration = (float) Math.sqrt(
2.0 * (distanceToApex + distanceToEdge) / Math.abs(mDeceleration));
@@ -848,12 +850,14 @@ public class OverScroller {
private void onEdgeReached() {
// mStart, mVelocity and mStartTime were adjusted to their values when edge was reached.
float distance = mVelocity * mVelocity / (2.0f * Math.abs(mDeceleration));
// The float cast below is necessary to avoid integer overflow.
final float velocitySquared = (float) mVelocity * mVelocity;
float distance = velocitySquared / (2.0f * Math.abs(mDeceleration));
final float sign = Math.signum(mVelocity);
if (distance > mOver) {
// Default deceleration is not sufficient to slow us down before boundary
mDeceleration = - sign * mVelocity * mVelocity / (2.0f * mOver);
mDeceleration = - sign * velocitySquared / (2.0f * mOver);
distance = mOver;
}