handleDragStart method
The beginning of a drag operation.
If the game is not listening to tap events, this event will occur as soon as the user touches the screen. If the game uses both a MultiTapListener and a MultiDragListener simultaneously, then this event will fire once the user moves their finger away from the point of the initial touch.
Implementation
@override
void handleDragStart(int pointerId, DragStartDetails details) {
onDragStart(pointerId, DragStartInfo.fromDetails(this, details));
}