onChangeStart property

ValueChanged<SfRangeValues>? onChangeStart

The onChangeStart callback will be called when the user starts to tap or drag the range selector. This callback is only used to notify the user about the start interaction and it does not update the range selector value.

The last interacted thumb value will be passed to this callback. The value will be double or date time.

SfRangeValues _values = SfRangeValues(4.0, 6.0);

Widget build(BuildContext context) {
  return Scaffold(
    body: SfRangeSelector(
      min: 0,
      max: 10,
      initialValues: _values,
      onChangeStart: (SfRangeValues startValue) {
        print('Interaction start');
      child: Container(
        height: 150,
        color: Colors.green,

See also: • The onChangeEnd callback used to notify the user about the interaction end. • The onChanged callback used to update the slider thumb value.


final ValueChanged<SfRangeValues>? onChangeStart;