async_button_builder

AsyncButtonBuilder offers a simple way to extend any type of button with an asynchronous aspect. It allows adding loading, disabled, errored and completed states (with fluid animation between each) on top of buttons that perform asynchronous tasks.

Getting Started

Include the package:

  async_button_builder: <latest_version>

Wrap the builder around a button, passing the onPressed and child element to builder instead of the button directly. These two are the only required fields.

AsyncButtonBuilder(
  child: Text('Click Me'),
  onPressed: () async {
    await Future.delayed(Duration(seconds: 1));
  },
  builder: (context, child, callback, _) {
    return TextButton(
      child: child,
      onPressed: callback,
    );
  },
),

The fourth value in the builder allows you listen to the loading state. This can be used to conditionally style the button. This package depends freezed in order to create a sealed union to better handle the possible states.

AsyncButtonBuilder(
  child: Text('Click Me'),
  loadingWidget: Text('Loading...'),
  onPressed: () async {
    await Future.delayed(Duration(seconds: 1));

    // See the examples file for a way to handle timeouts
    throw 'yikes';
  },
  builder: (context, child, callback, buttonState) {
    final buttonColor = buttonState.when(
      idle: () => Colors.yellow[200],
      loading: () => Colors.grey,
      success: () => Colors.orangeAccent,
      error: () => Colors.orange,
    );

    return OutlinedButton(
      child: child,
      onPressed: callback,
      style: OutlinedButton.styleFrom(
        primary: Colors.black,
        backgroundColor: buttonColor,
      ),
    );
  },
),

You can also drive the state of the button yourself using the buttonState field:

AsyncButtonBuilder(
  buttonState: ButtonState.completing(),
  // ...
),

async_button_builder even works for custom buttons. You can define your own widgets for loading, error, and completion as well as define the transitions between them. This example is a little verbose but shows some of what's possible.

AsyncButtonBuilder(
  child: Padding(
    padding: const EdgeInsets.symmetric(
      horizontal: 16.0,
      vertical: 8.0,
    ),
    child: Text(
      'Click Me',
      style: TextStyle(color: Colors.white),
    ),
  ),
  loadingWidget: Padding(
    padding: const EdgeInsets.all(8.0),
    child: SizedBox(
      height: 16.0,
      width: 16.0,
      child: CircularProgressIndicator(
        valueColor: AlwaysStoppedAnimation<Color>(Colors.white),
      ),
    ),
  ),
  successWidget: Padding(
    padding: const EdgeInsets.all(4.0),
    child: Icon(
      Icons.check,
      color: Colors.purpleAccent,
    ),
  ),
  onPressed: () async {
    await Future.delayed(Duration(seconds: 2));
  },
  loadingSwitchInCurve: Curves.bounceInOut,
  loadingTransitionBuilder: (child, animation) {
    return SlideTransition(
      position: Tween<Offset>(
        begin: Offset(0, 1.0),
        end: Offset(0, 0),
      ).animate(animation),
      child: child,
    );
  },
  builder: (context, child, callback, state) {
    return Material(
      color: state.maybeWhen(
        success: () => Colors.purple[100],
        orElse: () => Colors.blue,
      ),
      // This prevents the loading indicator showing below the
      // button
      clipBehavior: Clip.hardEdge,
      shape: StadiumBorder(),
      child: InkWell(
        child: child,
        onTap: callback,
      ),
    );
  },
),

Issues and PR's welcome

Libraries

async_button_builder