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这是我写的从一个Polygon获取中心点坐标的代码：



/**

* Author:Wu Yongfeng

* MSN/Email:warrenwyf@gmail.com

*/

package wuyf

{


import com.esri.ags.geometry.Extent;

import com.esri.ags.geometry.MapPoint;

import com.esri.ags.geometry.Polygon;

public class GeometryUtil

{


/**

* 获取多边形的重心

* @param polygon 多边形

* @return 重心点

*

*/

static public function getGravityCenter(polygon polygon):MapPoint

{


var ext:Extent = polygon.extent;

var p0:MapPoint = new MapPoint(ext.xmin, ext.ymin);

var momentX:Number = 0;

var momentY:Number = 0;

var weight:Number = 0;

for (var i:int=0; i
{


var pts:Array = polygon.rings

as Array;


for ( var j:int=0; j
{


var p1:MapPoint = polygon.getPoint(i, j);

var p2:MapPoint;

if( j==pts.length-1 )

{


p2 = polygon.getPoint(i, 0);

}

else

{


p2 = polygon.getPoint(i, j+1);

}

var dWeight:Number = (p1.x-p0.x)*(p2.y-p1.y)

– (p1.x-p0.x)*(p0.y-p1.y)/2

– (p2.x-p0.x)*(p2.y-p0.y)/2

– (p1.x-p2.x)*(p2.y-p1.y)/2;

weight += dWeight;

var pTmp:MapPoint = new MapPoint((p1.x+p2.x)/2, (p1.y+p2.y)/2);

var gravityX:Number = p0.x + (pTmp.x-p0.x)*2/3;

var gravityY:Number = p0.y + (pTmp.y-p0.y)*2/3;

momentX += gravityX*dWeight;

momentY += gravityY*dWeight;

}

}

return new MapPoint(momentX/weight, momentY/weight);

}

}

}

看看效果：