pan method
Implementation
void pan(double deltaFraction) {
if (_disposed) return;
if (!constraints.enablePan) return;
if (!deltaFraction.isFinite) return;
value = value.panBy(deltaFraction);
}
void pan(double deltaFraction) {
if (_disposed) return;
if (!constraints.enablePan) return;
if (!deltaFraction.isFinite) return;
value = value.panBy(deltaFraction);
}