Scrollable press-drag-release gestures unconditionally fling #5870
Description
ScrollableState currently handles drag release events by starting a scroll offset animation, even when the corresponding fling gesture's velocity is below the threshold:
void _handleDragEnd(DragEndDetails details) {
final double scrollVelocity = pixelDeltaToScrollOffset(details.velocity.pixelsPerSecond);
fling(scrollVelocity).then((Null _) {
_endScroll(details: details);
});
}
Future<Null> fling(double scrollVelocity) {
if (scrollVelocity.abs() > kPixelScrollTolerance.velocity || !_controller.isAnimating)
return _startToEndAnimation(scrollVelocity);
return new Future<Null>.value();
}
The || !_controller.isAnimating expression causes the fling animation to be started even when the velocity is below threshold (unless there's scroll animation underway already).