ClipShadowPath.dart

import 'package:flutter/material.dart';

@immutable
class ClipShadowPath extends StatelessWidget {
  final Shadow shadow;
  final CustomClipper<Path> clipper;
  final Widget child;

  ClipShadowPath({
    @required this.shadow,
    @required this.clipper,
    @required this.child,
  });

  @override
  Widget build(BuildContext context) {
    return CustomPaint(
      painter: _ClipShadowShadowPainter(
        clipper: this.clipper,
        shadow: this.shadow,
      ),
      child: ClipPath(child: child, clipper: this.clipper),
    );
  }
}

class _ClipShadowShadowPainter extends CustomPainter {
  final Shadow shadow;
  final CustomClipper<Path> clipper;

  _ClipShadowShadowPainter({@required this.shadow, @required this.clipper});

  @override
  void paint(Canvas canvas, Size size) {
    var paint = shadow.toPaint();
    var clipPath = clipper.getClip(size).shift(shadow.offset);
    canvas.drawPath(clipPath, paint);
  }

  @override
  bool shouldRepaint(CustomPainter oldDelegate) {
    return true;
  }
}

@coman3 I've just been fighting a bug in my application, where the child of my ClipShadowPath is a stateful widget, but it was loosing its state every time its parent's build method was called. After an hour fighting it, I finally understood that it was caused by the CustomPaint widget defining its key as a UniqueKey().

Someone already posted a similar situation before, and as you noted yourself, there are probably others this happens to:

Note that using key: UniqueKey() broke my AnimatedOpacity (and likely other animations) that was used as a child of ClipShadowPath.

Thanks for the tip, I'm sure someone was fighting with this in the past since that change 👍

Could you remove the key definition from your gist? I'm not sure what benefit it brings really, but it certainly causes many other developers to loose time figuring out why their application is buggy.

Sorry if this wasted ya time, I've removed it :)