dart - Flutter button with custom shape - (triangle)

Question

I've created a circular button which in this case is RawMaterialButton and I'm trying to use CustomPaint to create a triangle shape in the centre of it, but it's saying ShapesPainter is not defined for the class ClearButton'. I tried other buttons but couldn't get any of them to acceptShapesPainter`.

RawMaterialButton(
          child: CustomPaint(
            painter: ShapesPainter(),
            child: Container(
              height: 40,
            ),
          ),
          onPressed: onPressed,
          constraints: BoxConstraints.tightFor(
            width: 90.0,
            height: 90.0,
          ),
          shape: RoundedRectangleBorder(),
          fillColor: Colors.transparent,
        )

Which button type should be used with ShapesPainter or how can I otherwise create a circular button with a triangle or another shape in the centre?

This is the button I was trying to create which as you can see is basically a circular button with a triangle.

Answer 1

You can do it by creating your own custom painter implementation.

Triangle Painter

class TrianglePainter extends CustomPainter {
  final Color strokeColor;
  final PaintingStyle paintingStyle;
  final double strokeWidth;

  TrianglePainter({this.strokeColor = Colors.black, this.strokeWidth = 3, this.paintingStyle = PaintingStyle.stroke});

  @override
  void paint(Canvas canvas, Size size) {
    Paint paint = Paint()
      ..color = strokeColor
      ..strokeWidth = strokeWidth
      ..style = paintingStyle;

    canvas.drawPath(getTrianglePath(size.width, size.height), paint);
  }

  Path getTrianglePath(double x, double y) {
    return Path()
      ..moveTo(0, y)
      ..lineTo(x / 2, 0)
      ..lineTo(x, y)
      ..lineTo(0, y);
  }

  @override
  bool shouldRepaint(TrianglePainter oldDelegate) {
    return oldDelegate.strokeColor != strokeColor ||
        oldDelegate.paintingStyle != paintingStyle ||
        oldDelegate.strokeWidth != strokeWidth;
  }
}

USAGE

class HomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: RawMaterialButton(
          onPressed: () {},
          child: CustomPaint(
            painter: TrianglePainter(
              strokeColor: Colors.blue,
              strokeWidth: 10,
              paintingStyle: PaintingStyle.fill,
            ),
            child: Container(
              height: 180,
              width: 200,
            ),
          ),
        ),
      ),
    );
  }
}