Openlayers在Google地图下测距测面积.doc

在地图的panel内添加控件： vlayer = new OpenLayers.Layer.Vector(控件层); map.addLayer(vlayer); / 定义面板 var panel = new OpenLayers.Control.Panel();panel.addControls(new OpenLayers.Control.DrawFeature( vlayer, OpenLayers.Handler. Path, title: 测距, featureAdded: LengthFeatureAdd ), new OpenLayers.Control.DrawFeature ( vlayer, OpenLayers.Handler. Polygon, title: 测面积,featureAdded: AreaFeatureAdd ) ); /添加控制面板map.addControl(panel);添加js代码文件：Ranging.js,记得添加引用。 /关闭Pupup的弹出对话框 function onPopupClose(evt) vlayer.removeFeatures(vlayer.features); map.removePopup(selectedFeature.popup); selectedFeature.popup.destroy(); selectedFeature.popup = null; /测距 var EARTH_RADIUS = 6378137; function rad(d) return d * Math.PI / 180.0; function GetDistance(lat1, lon1, lat2, lon2) var radLat1 = rad(lat1); var radLat2 = rad(lat2); var a = radLat1 - radLat2; var b = rad(lon1) - rad(lon2); var s = 2 * Math.asin(Math.sqrt(Math.pow(Math.sin(a/2),2) +Math.cos(radLat1)*Math.cos(radLat2)*Math.pow(Math.sin(b/2),2); s = s * EARTH_RADIUS; s = Math.round(s * 10000) / 10000; return s; function LengthFeatureAdd(feature) var distance=0; var source = new Proj4js.Proj(EPSG:900913); var dest = new Proj4js.Proj(WGS84); for(var i=1;ponents.length;+i) /投影转换 var p1 = new Proj4js.Point(ponentsi-1.x,ponentsi-1.y); Proj4js.transform(source, dest, p1); var p2 = new Proj4js.Point(ponentsi.x,ponentsi.y); Proj4js.transform(source, dest, p2); distance=distance+GetDistance(p1.y,p1.x,p2.y,p2.x); popup = new OpenLayers.Popup.FramedCloud(chicken, feature.geometry.getBounds().getCenterLonLat(), null, 所测距离为: + distance.toFixed(1) + 米+, null, true, onPopupClose ); popup.autoSize = true ; feature.popup = popup; selectedFeature = feature; map.addPopup(popup); function AreaFeatureAdd(feature) var pointX=new Array(); var pointY=new Array(); var source = new Proj4js.Proj(EPSG:900913); var dest = new Proj4js.Proj(WGS84); for(var i=0;ponents.length-1;+i) /投影转换 var p = new Proj4js.Point(ponentsi.x,ponentsi.y); Proj4js.transform(source, dest, p); ponentsi.x=p.x; ponentsi.y=p.y; pointX.push(p.x); pointY.push(p.y); pointX.push(pointX0); pointY.push(pointY0); var area = calcArea(pointX,pointY); var inperd=OpenLayers.INCHES_PER_UNITkm; if(inperd) var inperm=OpenLayers.INCHES_PER_UNITthis.map.getUnits(); area*=Math.pow(inperm/inperd),2); popup = new OpenLayers.Popup.FramedCloud(chicken, feature.geometry.getBounds().getCenterLonLat(), null, 所测面积为: + area.toFixed(2) + 平方千米+, null, true, onPopupClose ); popup.autoSize = true ; feature.popup = popup; selectedFeature = feature; map.addPopup(popup); /算法依据：球面多边形计算面积的关键在于计算多边形所有角的度数. /对于球面n边形,所有角的和为S,球的半径为R,那么其面积就是 /R2*(S-(n-2)*Pi) function calcArea(PointX,PointY) var Count = PointX.length if (Count3) var mtotalArea = 0; if(PointX0!=PointXCount-1)|(PointY0!=PointYCount-1) return; /一个顶角的三个点 var LowX=0.0; var LowY=0.0; var MiddleX=0.0; var MiddleY=0.0; var HighX=0.0; var HighY=0.0; var AM = 0.0; var BM = 0.0; var CM = 0.0; var AL = 0.0; var BL = 0.0; var CL = 0.0; var AH = 0.0; var BH = 0.0; var CH = 0.0; var CoefficientL = 0.0; var CoefficientH = 0.0; var ALtangent = 0.0; var BLtangent = 0.0; var CLtangent = 0.0; var AHtangent = 0.0; var BHtangent = 0.0; var CHtangent = 0.0; var ANormalLine = 0.0; var BNormalLine = 0.0; var CNormalLine = 0.0; var OrientationValue = 0.0; var AngleCos = 0.0; var Sum1 = 0.0; var Sum2 = 0.0; var Count2 = 0; var Count1 = 0; var Sum = 0.0; var Radius = 6370000; /求每个顶点的顶角的度数，并相加 for(i=0;i0) Sum1 += AngleCos; Count1 +; else Sum2 += AngleCos; Count2 +; if(Sum1Sum2) Sum = Sum1+(2*Math.PI*Count2-Sum2);