onIncrease property Null safety

VoidCallback? onIncrease

The handler for SemanticsAction.increase.

This is a request to increase the value represented by the widget. For example, this action might be recognized by a slider control.

VoiceOver users on iOS can trigger this action by swiping up with one finger. TalkBack users on Android can trigger this action by pressing the volume up button.


VoidCallback? get onIncrease => _onIncrease;
void onIncrease=(VoidCallback? handler)


set onIncrease(VoidCallback? handler) {
  if (_onIncrease == handler)
  final bool hadValue = _onIncrease != null;
  _onIncrease = handler;
  if ((handler != null) != hadValue)