implemented topbar shape

lib/screens/metering/components/topbar/topbar_shape.dart

@@ -0,0 +1,48 @@
+import 'package:flutter/material.dart';
+
+class TopBarShape extends CustomPainter {
+  final Color color;
+  final Size appendixSize;
+  final double radius;
+
+  TopBarShape({
+    required this.color,
+    required this.appendixSize,
+    required this.radius,
+  });
+
+  @override
+  void paint(Canvas canvas, Size size) {
+    final paint = Paint()..color = color;
+    final path = Path();
+    final circularRadius = Radius.circular(radius);
+    path.moveTo(size.width, 0);
+    path.lineTo(size.width, size.height - radius);
+    path.arcToPoint(
+      Offset(size.width - radius, size.height),
+      radius: circularRadius,
+    );
+    path.lineTo(size.width - appendixSize.width + radius, size.height);
+    path.arcToPoint(
+      Offset(size.width - appendixSize.width, size.height - radius),
+      radius: circularRadius,
+    );
+    path.lineTo(size.width - appendixSize.width, size.height - appendixSize.height + radius);
+    path.arcToPoint(
+      Offset(size.width - appendixSize.width - radius, size.height - appendixSize.height),
+      radius: circularRadius,
+      clockwise: false,
+    );
+    path.lineTo(radius, size.height - appendixSize.height);
+    path.arcToPoint(
+      Offset(0, size.height - appendixSize.height - radius),
+      radius: circularRadius,
+    );
+    path.lineTo(0, 0);
+    path.close();
+    canvas.drawPath(path, paint);
+  }
+
+  @override
+  bool shouldRepaint(CustomPainter oldDelegate) => false;
+}