double border color.dart

gistfile1.txt

import 'package:flutter/material.dart';

class CustomDoubleBorder extends OutlinedBorder {
  final double innerRadius;
  final double outerRadius;
  final BorderSide innerBorderSide;
  final BorderSide outerBorderSide;

  CustomDoubleBorder({
    this.innerRadius = 4,
    this.outerRadius = 4,
    this.innerBorderSide = const BorderSide(color: Colors.white, width: 3),
    this.outerBorderSide = const BorderSide(color: Colors.red, width: 4),
  });

  @override
  CustomDoubleBorder copyWith({BorderSide? side}) {
    return CustomDoubleBorder(
      innerBorderSide: side ?? innerBorderSide,
      outerBorderSide: side ?? outerBorderSide,
      innerRadius: innerRadius,
      outerRadius: outerRadius,
    );
  }

  @override
  EdgeInsetsGeometry get dimensions => const EdgeInsets.all(4);

  @override
  CustomDoubleBorder scale(double t) {
    return CustomDoubleBorder(
      innerRadius: innerRadius * t,
      outerRadius: outerRadius * t,
      innerBorderSide: innerBorderSide.scale(t),
      outerBorderSide: outerBorderSide.scale(t),
    );
  }

  @override
  Path getInnerPath(Rect rect, {TextDirection? textDirection}) {
    final innerPath = Path()
      ..addRRect(RRect.fromRectAndRadius(
          rect.deflate(outerBorderSide.width + innerBorderSide.width),
          Radius.circular(4)));
    return innerPath;
  }

  @override
  Path getOuterPath(Rect rect, {TextDirection? textDirection}) {
    final outerPath = Path()
      ..addRRect(RRect.fromRectAndRadius(
          rect.deflate(outerBorderSide.width), Radius.circular(4)));
    return outerPath;
  }

  @override
  void paint(Canvas canvas, Rect rect, {TextDirection? textDirection}) {
    final inner = getInnerPath(rect, textDirection: textDirection);
    final outer = getOuterPath(rect, textDirection: textDirection);

    final innerPaint = innerBorderSide.toPaint();
    final outerPaint = outerBorderSide.toPaint();


    canvas.drawPath(outer, outerPaint);
    canvas.drawPath(inner, innerPaint);

    // Calculate the corner radius difference

  }
}

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: ElevatedButton(
            child: Text('Hello'),
            onPressed: () {},
            style: TextButton.styleFrom(shape: CustomDoubleBorder(
              innerBorderSide: BorderSide(color: Theme.of(context).colorScheme.onPrimary,width: 1),
              outerBorderSide: BorderSide(color: Theme.of(context).colorScheme.primary,width: 2),
            )),
          ),
        ),
      ),
    );
  }
}

void main() {
  runApp(MyApp());
}