BMFCircle constructor
- {@required BMFCoordinate center,
 - @required double radius,
 - int width: 5,
 - Color strokeColor: Colors.blue,
 - Color fillColor: Colors.red,
 - BMFLineDashType lineDashType: BMFLineDashType.LineDashTypeNone,
 - int zIndex: 0,
 - bool visible: true}
 
BMFCircle构造方法
Implementation
BMFCircle(
    {@required this.center,
    @required this.radius,
    this.width: 5,
    this.strokeColor: Colors.blue,
    this.fillColor: Colors.red,
    this.lineDashType: BMFLineDashType.LineDashTypeNone,
    int zIndex: 0,
    bool visible: true})
    : super(zIndex: zIndex, visible: visible);