MaterialState

sample.packages.flutter.lib.src.material.material_state.379.

This example defines a subclass of [RoundedRectangleBorder] and an implementation of [MaterialStateOutlinedBorder], that resolves to [RoundedRectangleBorder] when its widget is selected.

  
import 'package:flutter/material.dart';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  static const String _title = 'Flutter Code Sample';

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      title: _title,
      home: MyStatefulWidget(),
    );
  }
}

class SelectedBorder extends RoundedRectangleBorder
    implements MaterialStateOutlinedBorder {
  @override
  OutlinedBorder? resolve(Set states) {
    if (states.contains(MaterialState.selected)) {
      return const RoundedRectangleBorder();
    }
    return null; // Defer to default value on the theme or widget.
  }
}

class MyStatefulWidget extends StatefulWidget {
  const MyStatefulWidget({Key? key}) : super(key: key);

  @override
  State createState() => _MyStatefulWidgetState();
}

class _MyStatefulWidgetState extends State {
  bool isSelected = true;

  @override
  Widget build(BuildContext context) {
    return Material(
      child: FilterChip(
        label: const Text('Select chip'),
        selected: isSelected,
        onSelected: (bool value) {
          setState(() {
            isSelected = value;
          });
        },
        shape: SelectedBorder(),
      ),
    );
  }
}
  

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