Flutter: vibrate on device for non-standard length of time

Question

I am trying to build a Flutter application for Android that vibrates the phone both

• for sufficiently long and sufficiently forcefully that even when the user's phone is in their pocket, the vibration is noticeable
• in a specific pattern which the user can identify (like Morse code)

I have found ways of producing haptic feedback, such as HapticFeedback.vibrate, HapticFeedback.lightImpact; however, none of these allow me to control the length of the vibration.

Is there any way in which I can make the phone vibrate for a specified length of time (e.g. 250ms)?

Answer 1

I'm answering my own question as I've found a solution that works well for Android; using the plugin vibrate, the following code works perfectly well to send custom lengths of vibration and patterns of vibration:

class GoodVibrations {
  static const MethodChannel _channel = const MethodChannel(
      'github.com/clovisnicolas/flutter_vibrate');

  ///Vibrate for ms milliseconds
  static Future vibrate(ms) =>
      _channel.invokeMethod("vibrate", {"duration": ms});

  ///Take in an Iterable<int> of the form
  ///[l_1, p_1, l_2, p_2, ..., l_n]
  ///then vibrate for l_1 ms,
  ///pause for p_1 ms,
  ///vibrate for l_2 ms,
  ///...
  ///and vibrate for l_n ms.
  static Future vibrateWithPauses(Iterable<int> periods) async {
    bool isVibration = true;
    for (int d in periods) {
      if (isVibration && d > 0) {
        vibrate(d);
      }
      await new Future.delayed(Duration(milliseconds: d));
      isVibration = !isVibration;
    }
  }
}