onViewFinderTap method
Implementation
void onViewFinderTap(TapDownDetails details, BoxConstraints constraints) {
if (controller == null) {
return;
}
final Offset offset = Offset(
details.localPosition.dx / constraints.maxWidth,
details.localPosition.dy / constraints.maxHeight,
);
controller!.setExposurePoint(offset);
controller!.setFocusPoint(offset);
}