Fixed CircleMarker's incorrect appearance and size

example/lib/pages/circle.dart

@@ -12,12 +12,21 @@ class CirclePage extends StatelessWidget {
   Widget build(BuildContext context) {
     final circleMarkers = <CircleMarker>[
       CircleMarker(
-          point: const LatLng(51.5, -0.09),
-          color: Colors.blue.withOpacity(0.7),
-          borderStrokeWidth: 2,
-          useRadiusInMeter: true,
-          radius: 2000 // 2000 meters | 2 km
-          ),
+        point: const LatLng(51.5, -0.09),
+        color: Colors.blue.withOpacity(0.7),
+        borderColor: Colors.black,
+        borderStrokeWidth: 2,
+        useRadiusInMeter: true,
+        radius: 2000, // 2000 meters
+      ),
+      CircleMarker(
+        point: const LatLng(51.4937, -0.6638), // Dorney Lake is ~2km long
+        color: Colors.green.withOpacity(0.9),
+        borderColor: Colors.black,
+        borderStrokeWidth: 2,
+        useRadiusInMeter: true,
+        radius: 1000, // 1000 meters
+      ),
     ];
 
     return Scaffold(

lib/src/layer/circle_layer.dart

@@ -37,14 +37,10 @@ class CircleLayer extends StatelessWidget {
   Widget build(BuildContext context) {
     final map = MapCamera.of(context);
     return MobileLayerTransformer(
-      child: LayoutBuilder(
-        builder: (context, bc) {
-          final size = Size(bc.maxWidth, bc.maxHeight);
-          return CustomPaint(
-            painter: CirclePainter(circles, map),
-            size: size,
-          );
-        },
+      child: CustomPaint(
+        painter: CirclePainter(circles, map),
+        size: Size(map.size.x, map.size.y),
+        isComplex: true,
       ),
     );
   }
@@ -65,7 +61,8 @@ class CirclePainter extends CustomPainter {
 
     // Let's calculate all the points grouped by color and radius
     final points = <Color, Map<double, List<Offset>>>{};
-    final pointsBorder = <Color, Map<double, List<Offset>>>{};
+    final pointsFilledBorder = <Color, Map<double, List<Offset>>>{};
+    final pointsBorder = <Color, Map<double, Map<double, List<Offset>>>>{};
     for (final circle in circles) {
       final offset = map.getOffsetFromOrigin(circle.point);
       double radius = circle.radius;
@@ -79,52 +76,86 @@ class CirclePainter extends CustomPainter {
       points[circle.color]![radius]!.add(offset);
 
       if (circle.borderStrokeWidth > 0) {
-        double radiusBorder = circle.radius + circle.borderStrokeWidth;
-        if (circle.useRadiusInMeter) {
-          final rBorder = distance.offset(circle.point, radiusBorder, 180);
-          final deltaBorder = offset - map.getOffsetFromOrigin(rBorder);
-          radiusBorder = deltaBorder.distance;
+        // Check if color have some transparency or not
+        // As drawPoints is more efficient than drawCircle
+        if (circle.color.alpha == 0xFF) {
+          double radiusBorder = circle.radius + circle.borderStrokeWidth;
+          if (circle.useRadiusInMeter) {
+            final rBorder = distance.offset(circle.point, radiusBorder, 180);
+            final deltaBorder = offset - map.getOffsetFromOrigin(rBorder);
+            radiusBorder = deltaBorder.distance;
+          }
+          pointsFilledBorder[circle.borderColor] ??= {};
+          pointsFilledBorder[circle.borderColor]![radiusBorder] ??= [];
+          pointsFilledBorder[circle.borderColor]![radiusBorder]!.add(offset);
+        } else {
+          double realRadius = circle.radius;
+          if (circle.useRadiusInMeter) {
+            final rBorder = distance.offset(circle.point, realRadius, 180);
+            final deltaBorder = offset - map.getOffsetFromOrigin(rBorder);
+            realRadius = deltaBorder.distance;
+          }
+          pointsBorder[circle.borderColor] ??= {};
+          pointsBorder[circle.borderColor]![circle.borderStrokeWidth] ??= {};
+          pointsBorder[circle.borderColor]![circle.borderStrokeWidth]![
+              realRadius] ??= [];
+          pointsBorder[circle.borderColor]![circle.borderStrokeWidth]![
+                  realRadius]!
+              .add(offset);
         }
-        pointsBorder[circle.borderColor] ??= {};
-        pointsBorder[circle.borderColor]![radiusBorder] ??= [];
-        pointsBorder[circle.borderColor]![radiusBorder]!.add(offset);
       }
     }
 
     // Now that all the points are grouped, let's draw them
-    // First by border in order to be under the circle
+    final paintBorder = Paint()..style = PaintingStyle.stroke;
     for (final color in pointsBorder.keys) {
-      final paint = Paint()
-        ..strokeCap = StrokeCap.round
-        ..isAntiAlias = false
-        ..color = color;
-      final pointsByRadius = pointsBorder[color]!;
+      final paint = paintBorder..color = color;
+      for (final borderWidth in pointsBorder[color]!.keys) {
+        final pointsByRadius = pointsBorder[color]![borderWidth]!;
+        final radiusPaint = paint..strokeWidth = borderWidth;
+        for (final radius in pointsByRadius.keys) {
+          final pointsByRadiusColor = pointsByRadius[radius]!;
+          for (final offset in pointsByRadiusColor) {
+            _paintCircle(canvas, offset, radius, radiusPaint);
+          }
+        }
+      }
+    }
+
+    // Then the filled border in order to be under the circle
+    final paintPoint = Paint()
+      ..isAntiAlias = false
+      ..strokeCap = StrokeCap.round;
+    for (final color in pointsFilledBorder.keys) {
+      final paint = paintPoint..color = color;
+      final pointsByRadius = pointsFilledBorder[color]!;
       for (final radius in pointsByRadius.keys) {
         final pointsByRadiusColor = pointsByRadius[radius]!;
-        final radiusPaint = paint..strokeWidth = radius;
-        _paintCircle(canvas, pointsByRadiusColor, radiusPaint);
+        final radiusPaint = paint..strokeWidth = radius * 2;
+        _paintPoints(canvas, pointsByRadiusColor, radiusPaint);
       }
     }
 
     // And then the circle
     for (final color in points.keys) {
-      final paint = Paint()
-        ..isAntiAlias = false
-        ..strokeCap = StrokeCap.round
-        ..color = color;
+      final paint = paintPoint..color = color;
       final pointsByRadius = points[color]!;
       for (final radius in pointsByRadius.keys) {
         final pointsByRadiusColor = pointsByRadius[radius]!;
-        final radiusPaint = paint..strokeWidth = radius;
-        _paintCircle(canvas, pointsByRadiusColor, radiusPaint);
+        final radiusPaint = paint..strokeWidth = radius * 2;
+        _paintPoints(canvas, pointsByRadiusColor, radiusPaint);
       }
     }
   }
 
-  void _paintCircle(Canvas canvas, List<Offset> offsets, Paint paint) {
+  void _paintPoints(Canvas canvas, List<Offset> offsets, Paint paint) {
     canvas.drawPoints(PointMode.points, offsets, paint);
   }
 
+  void _paintCircle(Canvas canvas, Offset offset, double radius, Paint paint) {
+    canvas.drawCircle(offset, radius, paint);
+  }
+
   @override
   bool shouldRepaint(CirclePainter oldDelegate) => false;
 }