panZoomStart method Null safety
Create a PointerPanZoomStartEvent (e.g., trackpad scroll; not scroll wheel or finger-drag scroll) with the given delta.
By default, the time stamp on the event is Duration.zero. You can give a
specific time stamp by passing the timeStamp
argument.
Implementation
PointerPanZoomStartEvent panZoomStart(
Offset location, {
Duration timeStamp = Duration.zero
}) {
assert(!isPanZoomActive);
assert(kind == PointerDeviceKind.trackpad);
_location = location;
_pan = Offset.zero;
_isPanZoomActive = true;
return PointerPanZoomStartEvent(
timeStamp: timeStamp,
device: _device,
pointer: pointer,
position: location,
);
}