Called when the user presses on the render object for a long period of time.
Source
GestureLongPressCallback get onLongPress => _onLongPress;
Source
set onLongPress(GestureLongPressCallback value) {
if (_onLongPress == value)
return;
bool wasSemanticBoundary = isSemanticBoundary;
bool hadHandler = _onLongPress != null;
_onLongPress = value;
if ((value != null) != hadHandler)
markNeedsSemanticsUpdate(onlyChanges: isSemanticBoundary == wasSemanticBoundary);
}