zoomIn method
Implementation
void zoomIn(double focalFraction, {double factor = 2.0}) {
if (_disposed) return;
if (!constraints.enablePinchZoom && !constraints.enableDoubleTapZoom) {
return;
}
if (!factor.isFinite || factor <= 0 || !focalFraction.isFinite) return;
value = value.zoomAroundFraction(focalFraction, factor);
_applyConstraints();
}