updateMaterialState method

@protected ValueChanged<bool> updateMaterialState(WidgetState key, { ValueChanged<bool>? onChanged, })

Callback factory which accepts a WidgetState value and returns a closure to mutate materialStates and call setState.

Accepts an optional second named parameter, onChanged, which allows arbitrary functionality to be wired through the MaterialStateMixin. If supplied, the onChanged function is only called when child widgets report events that make changes to the current set of WidgetStates.

This example shows how to use the updateMaterialState callback factory in other widgets, including the optional onChanged callback.

class MyWidget extends StatefulWidget {
  const MyWidget({super.key, this.onPressed});

  /// Something important this widget must do when pressed.
  final VoidCallback? onPressed;

  @override
  State<MyWidget> createState() => MyWidgetState();
}

class MyWidgetState extends State<MyWidget> with MaterialStateMixin<MyWidget> {
  @override
  Widget build(BuildContext context) {
    return ColoredBox(
      color: isPressed ? Colors.black : Colors.white,
      child: InkWell(
        onHighlightChanged: updateMaterialState(
          WidgetState.pressed,
          onChanged: (bool val) {
            if (val) {
              widget.onPressed?.call();
            }
          },
        ),
      ),
    );
  }
}

Implementation

// TODO(framework): Add unit tests to this code snippet.
// https://github.com/flutter/flutter/issues/188530
///
/// This example shows how to use the [updateMaterialState] callback factory
/// in other widgets, including the optional [onChanged] callback.
///
/// ```dart
/// class MyWidget extends StatefulWidget {
///   const MyWidget({super.key, this.onPressed});
///
///   /// Something important this widget must do when pressed.
///   final VoidCallback? onPressed;
///
///   @override
///   State<MyWidget> createState() => MyWidgetState();
/// }
///
/// class MyWidgetState extends State<MyWidget> with MaterialStateMixin<MyWidget> {
///   @override
///   Widget build(BuildContext context) {
///     return ColoredBox(
///       color: isPressed ? Colors.black : Colors.white,
///       child: InkWell(
///         onHighlightChanged: updateMaterialState(
///           WidgetState.pressed,
///           onChanged: (bool val) {
///             if (val) {
///               widget.onPressed?.call();
///             }
///           },
///         ),
///       ),
///     );
///   }
/// }
/// ```
///
/// </callout-box>
@protected
ValueChanged<bool> updateMaterialState(WidgetState key, {ValueChanged<bool>? onChanged}) {
  return (bool value) {
    if (materialStates.contains(key) == value) {
      return;
    }
    setMaterialState(key, value);
    onChanged?.call(value);
  };
}