Flex Circle

package com.gis
{
    import com.esri.ags.SpatialReference;
    import com.esri.ags.geometry.MapPoint;
    import com.esri.ags.geometry.Polygon;

    public class Circle extends Polygon
    {
        private var pointNum:int = 100;

        /** 
         * @param center               圆心
         * @param radius               半径
         * @param spatialReference     空间参考
         * 
         */     
        public function Circle(center:MapPoint, radius:Number, spatialReference:SpatialReference=null)
        {
            super(null, spatialReference);
            this.addRing(getPoints(center, radius));
        }

        private function getPoints(center:MapPoint, radius:Number):Array
        {
            var x:Number;
            var y:Number;
            var points:Array=[];
            var angle:Number;
            for (var i:int=0; i < this.pointNum; i++)
            {
                angle = Math.PI * 2 * i / this.pointNum;
                x=center.x + radius * Math.sin(angle);
                y=center.y + radius * Math.cos(angle);
                points.push(new MapPoint(x, y));
            }
            return points;
        }
    }
}