Can't stop the fling!

Bug: 5335420

Fixed a bug in VelocityTracker where the output velocity was
not being set to zero when not available.

Added a condition to ensure that the velocity is at least
the minimum fling velocity before continuing.  If not, then
the user is trying to stop the fling and scroll more precisely.

Change-Id: I36634b0c3f7a9a09cf20c33f71d41163a8e33eed

Author: Jeff Brown

core/java/android/widget/AbsListView.java

@@ -3654,7 +3654,8 @@ public void run() {
                 vt.computeCurrentVelocity(1000, mMaximumVelocity);
                 final float yvel = -vt.getYVelocity(activeId);
 
-                if (scroller.isScrollingInDirection(0, yvel)) {
+                if (Math.abs(yvel) >= mMinimumVelocity
+                        && scroller.isScrollingInDirection(0, yvel)) {
                     // Keep the fling alive a little longer
                     postDelayed(this, FLYWHEEL_TIMEOUT);
                 } else {

core/java/android/widget/OverScroller.java

@@ -532,7 +532,7 @@ public boolean isScrollingInDirection(float xvel, float yvel) {
         final int dx = mScrollerX.mFinal - mScrollerX.mStart;
         final int dy = mScrollerY.mFinal - mScrollerY.mStart;
         return !isFinished() && Math.signum(xvel) == Math.signum(dx) &&
-        Math.signum(yvel) == Math.signum(dy);
+                Math.signum(yvel) == Math.signum(dy);
     }
 
     static class SplineOverScroller {

libs/ui/Input.cpp

@@ -1020,6 +1020,8 @@ bool VelocityTracker::getVelocity(uint32_t id, float* outVx, float* outVy) const
             return true;
         }
     }
+    *outVx = 0;
+    *outVy = 0;
     return false;
 }