snap method
Implementation
Future snap() async {
checkViewAndBound();
Offset snapTarget = getSnapTarget();
if (animateSnap) {
await move(snapTarget);
deltaNotifier.value = snapTarget;
} else
deltaNotifier.value = snapTarget;
delta = Offset.zero;
beginDragPosition = null;
updateDragPosition = null;
overrideDelta = Offset.zero;
if (onSnap != null) onSnap!(deltaNotifier.value);
}