onDecrease property
final
The handler for SemanticsAction.decrease.
This is a request to decrease the value represented by the widget. For example, this action might be recognized by a slider control.
If a value is set, decreasedValue must also be provided and onDecrease must ensure that value will be set to decreasedValue.
VoiceOver users on iOS can trigger this action by swiping down with one finger. TalkBack users on Android can trigger this action by pressing the volume down button.
Implementation
final VoidCallback? onDecrease;