ArcGIS for silverlight画圆如此简单

圆的实现原理：以中心点为一点，半径为一条边，旋转1弧度为顶角，连接弧度之间的两个顶点，组成一个三角形，循环360弧度，形成圆。

/// <summary>
/// 360度画圆
/// </summary>
/// <param name="radius">半径</param>
/// <param name="centerP">中心点</param>
/// <param name="color">填充色</param>
/// <returns>返回Graphic</returns>

public static Graphic GetEllipseGraphic(double radius, ComPoint centerP, string color)

{
Graphic result = new Graphic();
List<MapPoint> points = new List<MapPoint>();
for (double i = 0; i <= 360; i++)
{
points.Add(new MapPoint((centerP.X - Math.Cos(Math.PI  i / 180.0)  radius), (centerP.Y - Math.Sin(Math.PI  i / 180.0)  radius)));
}
PointCollection pCollection = new PointCollection(points);
Polygon g = new Polygon();
g.Rings.Add(pCollection);
result.Geometry = g;
  result.Symbol = Tools.DrawStyleTools.GetEllipseFillSymbol(color);//这里根据自己的需要定义样式
return result;
}