Inner Shadow in Flutter that actually works

inner_shadow.dart

// An inner shadow that fucking works. Thanks Flutter team "developers" and internet losers for wasting my time.

import 'dart:ui';

import 'package:flutter/material.dart';

class InnerShadow extends StatelessWidget {
  final Widget child;
  final double blurRadius;
  final Radius radius;
  final Offset offset;
  final Color color;
  final double opacity;

  const InnerShadow({
    required this.child,
    this.blurRadius = 10,
    this.radius = const Radius.circular(0),
    this.offset = const Offset(0, 0),
    this.color = Colors.black,
    this.opacity = 1,
    super.key,
  });

  @override
  Widget build(BuildContext context) {
    return Stack(
      children: [
        child,
        Positioned.fill(
          child: ClipRRect(
            borderRadius: BorderRadius.all(radius),
            clipBehavior: Clip.antiAlias,
            child: LayoutBuilder(
              builder: (context, constraints) {
                final outerWidth = constraints.maxWidth * 2;
                final outerHeight = constraints.maxHeight * 2;
                final width = constraints.maxWidth;
                final height = constraints.maxHeight;
                return OverflowBox(
                  maxWidth: outerWidth,
                  minWidth: outerWidth,
                  maxHeight: outerHeight,
                  minHeight: outerHeight,
                  child: Transform.translate(
                    offset: offset,
                    child: ImageFiltered(
                      imageFilter: ImageFilter.blur(sigmaX: blurRadius, sigmaY: blurRadius),
                      child: SizedBox(
                        width: outerWidth,
                        height: outerHeight,
                        child: ClipPath(
                          clipper: HoleClipper(radius: radius, size: constraints.biggest),
                          child: Container(
                            width: width,
                            height: height,
                            color: color.withAlpha((opacity * 255).toInt()),
                          ),
                        ),
                      ),
                    ),
                  ),
                );
              },
            ),
          ),
        ),
      ],
    );
  }
}

class HoleClipper extends CustomClipper<Path> {
  final Radius radius;
  final Size size;

  HoleClipper({this.radius = Radius.zero, required this.size});

  @override
  Path getClip(Size size) {
    Path path = Path()..addRect(Rect.fromLTWH(0, 0, size.width, size.height));

    Rect hole = Rect.fromCenter(
      center: Offset(size.width / 2, size.height / 2),
      width: this.size.width,
      height: this.size.height,
    );

    path.addRRect(RRect.fromRectAndRadius(hole, radius));
    return Path.combine(PathOperation.difference, path, Path()..addRRect(RRect.fromRectAndRadius(hole, radius)));
  }

  @override
  bool shouldReclip(HoleClipper oldClipper) => oldClipper.radius != radius || oldClipper.size != size;
}