Request for clarification using Canvas() and Paint() in flutter - flutter

Question

I use this method for custom markers on a map. I added a custom round background on the marker by using Canvas and Paint and just put those 2 together before returning it back to BitmapDescriptor using code I found which I don't understand very much in depth. I believe that is the reason my background and marker is getting clipped into this square box no matter how I try to adjust it.
My goal is to slightly increase the round background behind the marker. But, it just takes the limits of the marker/icon. If I increase its size, it gets clipped. Also wondering how canvas operations still works even if this class does not have a CustomPainter mixin
class IconLoader {
var vd = VendorDatabase();
late var iconPath;
var convertedIcon;
int iconSize = 200;
Future <BitmapDescriptor?> getIconWithBackground(vendorId) async {
...fetch icon path....
return processIconWithBackground(iconPath, iconSize).then((onValue) async {
return convertedIcon = BitmapDescriptor.fromBytes(onValue!);
});
Future<Uint8List?> processIconWithBackground(String path, int width) async {
final imageData = await rootBundle.load(path); //original code: loads the image into ByteData
// Performs Witchcraft
ui.Codec codec = await ui.instantiateImageCodec(imageData.buffer.asUint8List(), targetWidth: width);
// Something about animation if image is gif? <-- I'm not dealing with animations, how can i get rid of this?
ui.FrameInfo fi = await codec.getNextFrame();
// Converts ByteData to Png format?
var process = (await fi.image.toByteData(format: ui.ImageByteFormat.png))?.buffer.asUint8List();
// finally makes an Image Type Object
final iconImage = await decodeImageFromList(process!);
final pictureRecorder = ui.PictureRecorder(); // starts to record
final canvas = ui.Canvas(pictureRecorder);
canvas.scale(1.5);
_paintCircleStroke(canvas);
final imagePaint = ui.Paint();
canvas.drawImage(iconImage, Offset.zero, Paint());
final drawing = pictureRecorder.endRecording();// ends recording the "drawing"
final image = await drawing.toImage(iconSize.round(), iconSize.round());//converts this drawing to an image
final bytes = await image.toByteData(format: ui.ImageByteFormat.png);
return bytes?.buffer.asUint8List();}
void _paintCircleStroke (ui.Canvas canvas) {
double _circleOffset = iconSize /2;
double _circleStrokeWidth = iconSize / 10;
double _outlineCircleWidth = iconSize /2 ;// (_circleStrokeWidth / 2) ;
// canvas.scale(1.0);
final paint = ui.Paint()
..style = ui.PaintingStyle.fill
..color = ui.Color .fromRGBO(132, 123, 123, 1);
// ..strokeWidth = _circleStrokeWidth;
canvas.drawCircle(ui.Offset(_circleOffset, _circleOffset), _outlineCircleWidth, paint);