draw method
Implementation
@override
void draw(Canvas canvas, Paint paint, Offset offset, Size size) {
paint.reset();
paint.color = color;
paint.style = fill ? PaintingStyle.fill : PaintingStyle.stroke;
paint.strokeWidth = strokeWidth;
Path path = Path();
path.moveTo(offset.dx, offset.dy - size.height / 2);
path.lineTo(offset.dx + size.width / 2, offset.dy);
path.lineTo(offset.dx, offset.dy + size.height / 2);
path.lineTo(offset.dx - size.width / 2, offset.dy);
path.close();
canvas.drawPath(path, paint);
}