build method
new CustomPaint( painter: new SuccessPainter(color: SweetAlert.danger), )
Implementation
@override
Widget build(BuildContext context) {
  return new AnimatedBuilder(
      animation: animationController!,
      builder: (c, w) {
        return new Transform(
          transform: Matrix4.rotationX(
              math.radians(sequenceAnimation!['rotation'].value)),
          origin: new Offset(0.0, 32.0),
          child: new CustomPaint(
            painter: new _CustomPainter(
                color: SweetAlert.danger,
                fade: sequenceAnimation!['fade'].value,
                factor: sequenceAnimation!['fact'].value),
          ),
        );
      });
}