var paint = Paint();
    var path1 = Path();

    path1.moveTo(size.width / 3, size.height * 3 / 4);
    path1.lineTo(size.width / 2, size.height * 5 / 6);
    path1.lineTo(size.width * 3 / 4, size.height * 4 / 6);
    paint.style = PaintingStyle.fill;
    path1.close();

//     var trans = Float64List(16);
//     var ma = Matrix4.fromFloat64List(trans);
//     ma.setIdentity();

//     canvas.drawRect(Rect.fromCircle(
//       center: new Offset(size.width / 3, size.height * 3 / 4),
//       radius: 100,
//     ), paint);

//     canvas.clipRect(Rect.fromCircle(
//       center: new Offset(size.width / 3, size.height * 3 / 4),
//       radius: 100,
//     ));

    var path2 = Path();

    path2.addRect(Rect.fromCircle(
      center: new Offset(size.width / 3, size.height * 3 / 4),
      radius: 100,
    ));
    paint.style = PaintingStyle.fill;
    path2.close();

//     paint.shader = RadialGradient(
//       colors: [
//         Colors.red,
//         Colors.blue,
//       ],
//     ).createShader(Rect.fromCircle(
//       center: new Offset(size.width / 3, size.height * 3 / 4),
//       radius: 180.0,
//     ));

    var path3 = Path.combine(PathOperation.difference, path1, path2);

    canvas.drawPath(path3, paint);