Focus Detector Logo

Pub.dev Badge GitHub Build Badge Gitter Badge Effective Dart Badge MIT License Badge Flutter Platform Badge

Focus Detector

Get notified every time your widget appears or disappears from the screen.

Similar to onResume()/onPause() on Android and viewDidAppear()/viewDidDisappear() on iOS.

Focus Detector fires callbacks for you whenever something happens to take or give your widget focus. Such an event might be, for instance, the user:

  • Navigating to/from another screen;
  • Turning the device’s screen on/off while your widget is visible;
  • Switching to/from another app while your widget is visible;
  • Scrolling your widget in/out the screen;

Usage

@override
Widget build(BuildContext context) =>
    FocusDetector(
      onFocusLost: () {
        logger.i(
          'Focus Lost.'
          '\nTriggered when either [onVisibilityLost] or [onForegroundLost] '
          'is called.'
          '\nEquivalent to onPause() on Android or viewDidDisappear() on iOS.',
        );
      },
      onFocusGained: () {
        logger.i(
          'Focus Gained.'
          '\nTriggered when either [onVisibilityGained] or [onForegroundGained] '
          'is called.'
          '\nEquivalent to onResume() on Android or viewDidAppear() on iOS.',
        );
      },
      onVisibilityLost: () {
        logger.i(
          'Visibility Lost.'
          '\nIt means the widget is no longer visible within your app.',
        );
      },
      onVisibilityGained: () {
        logger.i(
          'Visibility Gained.'
          '\nIt means the widget is now visible within your app.',
        );
      },
      onForegroundLost: () {
        logger.i(
          'Foreground Lost.'
          '\nIt means, for example, that the user sent your app to the background by opening '
          'another app or turned off the device\'s screen while your '
          'widget was visible.',
        );
      },
      onForegroundGained: () {
        logger.i(
          'Foreground Gained.'
          '\nIt means, for example, that the user switched back to your app or turned the '
          'device\'s screen back on while your widget was visible.',
        );
      },
      child: Container(),
    );

Usage Scenarios

  • Turn on and off resource-consuming features, such as camera, location or bluetooth;
  • Sync your data with a remote API or local database;
  • Pause and resume video/audio playback or streaming;

Libraries

focus_detector