press method
void
press()
Presses at the current pointer location. Forwards a pointer-down when the pointer is over a widget surface; otherwise the press is blocked (it landed on world geometry or empty space).
Implementation
void press() {
if (_captured != null) return;
final target = _hovered;
if (target == null) return;
_captured = target;
_pressUv = _lastUv;
_pressTravel = 0.0;
target.controller.pointerDown(_lastUv, pointer: pointerId);
}