onPanDown method
Implementation
void onPanDown(DragDownDetails e) {
for (var item in _points) {
if (item.containPoint(e.localPosition)) {
item.selected = true;
_firstPoint = e.localPosition;
_pathPoint.add(item.centerPoint);
_updateView?.call();
_gestureIndex.add(item.index);
break;
}
}
}