I am trying to make a custom curved app bar, look like the example below

and after many tries here is my shot
source code :
class CustomShapeBorder extends ContinuousRectangleBorder {
@override
Path getOuterPath(Rect rect, {TextDirection textDirection}) {
final double innerCircleRadius = 150.0;
Path path = Path();
path.lineTo(0, rect.height);
path.cubicTo(rect.width / 1.5 - 40, rect.height + innerCircleRadius - 40, rect.width / 1.5 + 40,
rect.height + innerCircleRadius - 40, rect.width / 1.5 + 75, rect.height + 50);
path.quadraticBezierTo(
rect.width / 1.5 + (innerCircleRadius / 2) + 30, rect.height + 35, rect.width, rect.height);
path.lineTo(rect.width, 0.0);
path.close();
return path;
}
}
is there an easy way to make it for example SVG.

