More efficient way
I suggest you to draw a circle with CustomPainter. It's very easy and way more efficient than creating a bunch of widgets/masks:
/// Draws a circle if placed into a square widget.
class CirclePainter extends CustomPainter {
final _paint = Paint()
..color = Colors.red
..strokeWidth = 2
// Use [PaintingStyle.fill] if you want the circle to be filled.
..style = PaintingStyle.stroke;
@override
void paint(Canvas canvas, Size size) {
canvas.drawOval(
Rect.fromLTWH(0, 0, size.width, size.height),
_paint,
);
}
@override
bool shouldRepaint(CustomPainter oldDelegate) => false;
}
Usage:
Widget _buildCircle(BuildContext context) {
return SizedBox(
width: 20,
height: 20,
child: CustomPaint(
painter: CirclePainter(),
),
);
}