MarkerShapeConverter class

A JSON converter for MarkerShape class.

This converter serializes MarkerShape objects to JSON using their toJson method, and deserializes JSON maps back to MarkerShape objects using the factory constructor.

Example JSON representation:

{
  "type": "circle"
}

For shapes with orientation:

{
  "type": "triangle",
  "orientation": "right"
}

Usage with json_serializable:

@JsonSerializable()
class Port {
  @MarkerShapeConverter()
  final MarkerShape? shape; // null = use theme default

  Port(this.shape);
}