onChangeStart property

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

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

double _value = 4.0;

@override
Widget build(BuildContext context) {
  return Scaffold(
    body: SfSlider(
      min: 0,
      max: 10,
      value: _value,
      onChangeStart: (dynamic newValue) {
        print('Interaction starts');
      },
      onChanged: (dynamic newValue) {
        setState(() {
          _value = newValue;
        });
      },
    ),
  );
}

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

Implementation

SfSlider class