百度地图
类 BMapLib.GeoUtils
源文件: .
示例
/** * @fileoverview GeoUtils类提供若干几何算法，用来帮助用户判断点与矩形、 * 圆形、多边形线、多边形面的关系,并提供计算折线长度和多边形的面积的公式。 * 主入口类是GeoUtils， * 基于Baidu Map API 1.2。 * * @author Baidu Map Api Group * @version 1.2 */ /** * @namespace BMap的所有library类均放在BMapLib命名空间下 */ var BMapLib = window.BMapLib = BMapLib || {}; (function() { /** * 地球半径 */ var EARTHRADIUS = 6370996.81; /** * @exports GeoUtils as BMapLib.GeoUtils */ var GeoUtils = /** * GeoUtils类，静态类，勿需实例化即可使用 * @class GeoUtils类的入口。 * 该类提供的都是静态方法，勿需实例化即可使用。 */ BMapLib.GeoUtils = function(){ } /** * 判断点是否在矩形内 * @param {Point} point 点对象 * @param {Bounds} bounds 矩形边界对象 * @returns {Boolean} 点在矩形内返回true,否则返回false */ GeoUtils.isPointInRect = function(point, bounds){ //检查类型是否正确 if (!(point instanceof BMap.Point) || !(bounds instanceof BMap.Bounds)) { return false; } var sw = bounds.getSouthWest(); //西南脚点 var ne = bounds.getNorthEast(); //东北脚点 return (point.lng >= sw.lng && point.lng <= ne.lng && point.lat >= sw.lat && point.lat <= ne.lat); } /** * 判断点是否在圆形内 * @param {Point} point 点对象 * @param {Circle} circle 圆形对象 * @returns {Boolean} 点在圆形内返回true,否则返回false */ GeoUtils.isPointInCircle = function(point, circle){ //检查类型是否正确 if (!(point instanceof BMap.Point) || !(circle instanceof BMap.Circle)) { return false; } //point与圆心距离小于圆形半径，则点在圆内，否则在圆外 var c = circle.getCenter(); var r = circle.getRadius(); var dis = GeoUtils.getDistance(point, c); if(dis <= r){ return true; } else { return false; } } /** * 判断点是否在折线上 * @param {Point} point 点对象 * @param {Polyline} polyline 折线对象 * @returns {Boolean} 点在折线上返回true,否则返回false */ GeoUtils.isPointOnPolyline = function(point, polyline){ //检查类型 if(!(point instanceof BMap.Point) || !(polyline instanceof BMap.Polyline)){ return false; } //首先判断点是否在线的外包矩形内，如果在，则进一步判断，否则返回false var lineBounds = polyline.getBounds(); if(!this.isPointInRect(point, lineBounds)){ return false; } //判断点是否在线段上，设点为Q，线段为P1P2 ， //判断点Q在该线段上的依据是：( Q - P1 ) × ( P2 - P1 ) = 0，且 Q 在以 P1，P2为对角顶点的矩形内 var pts = polyline.getPath(); for(var i = 0; i < pts.length - 1; i++){ var curPt = pts[i]; var nextPt = pts[i + 1]; //首先判断point是否在curPt和nextPt之间，即：此判断该点是否在该线段的外包矩形内 if (point.lng >= Math.min(curPt.lng, nextPt.lng) && point.lng <= Math.max(curPt.lng, nextPt.lng) && point.lat >= Math.min(curPt.lat, nextPt.lat) && point.lat <= Math.max(curPt.lat, nextPt.lat)){ //判断点是否在直线上公式 var precision = (curPt.lng - point.lng) * (nextPt.lat - point.lat) - (nextPt.lng - point.lng) * (curPt.lat - point.lat); if(precision < 2e-10 && precision > -2e-10){ //实质判断是否接近0 return true; } } } return false; } /** * 判断点是否多边形内 * @param {Point} point 点对象 * @param {Polyline} polygon 多边形对象 * @returns {Boolean} 点在多边形内返回true,否则返回false */ GeoUtils.isPointInPolygon = function(point, polygon){ //检查类型 if(!(point instanceof BMap.Point) || !(polygon instanceof BMap.Polygon)){ return false; } //首先判断点是否在多边形的外包矩形内，如果在，则进一步判断，否则返回false var polygonBounds = polygon.getBounds(); if(!this.isPointInRect(point, polygonBounds)){ return false; } var pts = polygon.getPath();//获取多边形点 //下述代码来源：http://paulbourke.net/geometry/insidepoly/，进行了部分修改 //基本思想是利用射线法，计算射线与多边形各边的交点，如果是偶数，则点在多边形外，否则 //在多边形内。还会考虑一些特殊情况，如点在多边形顶点上，点在多边形边上等特殊情况。 var N = pts.length; var boundOrVertex = true; //如果点位于多边形的顶点或边上，也算做点在多边形内，直接返回true var intersectCount = 0;//cross points count of x var precision = 2e-10; //浮点类型计算时候与0比较时候的容差 var p1, p2;//neighbour bound vertices var p = point; //测试点 p1 = pts[0];//left vertex for(var i = 1; i <= N; ++i){ //check all rays if(p.equals(p1)){ return boundOrVertex;//p is an vertex } p2 = pts[i % N];//right vertex if(p.lat < Math.min(p1.lat, p2.lat) || p.lat > Math.max(p1.lat, p2.lat)){ //ray is outside of our interests p1 = p2; continue;//next ray left point } if(p.lat > Math.min(p1.lat, p2.lat) && p.lat < Math.max(p1.lat, p2.lat)){ //ray is crossing over by the algorithm (common part of) if(p.lng <= Math.max(p1.lng, p2.lng)){ //x is before of ray if(p1.lat == p2.lat && p.lng >= Math.min(p1.lng, p2.lng)){ //overlies on a horizontal ray return boundOrVertex; } if(p1.lng == p2.lng){ //ray is vertical if(p1.lng == p.lng){ //overlies on a vertical ray return boundOrVertex; }else{ //before ray ++intersectCount; } }else{ //cross point on the left side var xinters = (p.lat - p1.lat) * (p2.lng - p1.lng) / (p2.lat - p1.lat) + p1.lng;//cross point of lng if(Math.abs(p.lng - xinters) < precision){ //overlies on a ray return boundOrVertex; } if(p.lng < xinters){ //before ray ++intersectCount; } } } }else{ //special case when ray is crossing through the vertex if(p.lat == p2.lat && p.lng <= p2.lng){ //p crossing over p2 var p3 = pts[(i+1) % N]; //next vertex if(p.lat >= Math.min(p1.lat, p3.lat) && p.lat <= Math.max(p1.lat, p3.lat)){ //p.lat lies between p1.lat & p3.lat ++intersectCount; }else{ intersectCount += 2; } } } p1 = p2;//next ray left point } if(intersectCount % 2 == 0){ //偶数在多边形外 return false; } else { //奇数在多边形内 return true; } } /** * 将度转化为弧度 * @param {degree} Number 度 * @returns {Number} 弧度 */ GeoUtils.degreeToRad = function(degree){ return Math.PI * degree/180; } /** * 将弧度转化为度 * @param {radian} Number 弧度 * @returns {Number} 度 */ GeoUtils.radToDegree = function(rad){ return (180 * rad) / Math.PI; } /** * 将v值限定在a,b之间，纬度使用 */ function _getRange(v, a, b){ if(a != null){ v = Math.max(v, a); } if(b != null){ v = Math.min(v, b); } return v; } /** * 将v值限定在a,b之间，经度使用 */ function _getLoop(v, a, b){ while( v > b){ v -= b - a } while(v < a){ v += b - a } return v; } /** * 计算两点之间的距离,两点坐标必须为经纬度 * @param {point1} Point 点对象 * @param {point2} Point 点对象 * @returns {Number} 两点之间距离，单位为米 */ GeoUtils.getDistance = function(point1, point2){ //判断类型 if(!(point1 instanceof BMap.Point) || !(point2 instanceof BMap.Point)){ return 0; } point1.lng = _getLoop(point1.lng, -180, 180); point1.lat = _getRange(point1.lat, -74, 74); point2.lng = _getLoop(point2.lng, -180, 180); point2.lat = _getRange(point2.lat, -74, 74); var x1, x2, y1, y2; x1 = GeoUtils.degreeToRad(point1.lng); y1 = GeoUtils.degreeToRad(point1.lat); x2 = GeoUtils.degreeToRad(point2.lng); y2 = GeoUtils.degreeToRad(point2.lat); return EARTHRADIUS * Math.acos((Math.sin(y1) * Math.sin(y2) + Math.cos(y1) * Math.cos(y2) * Math.cos(x2 - x1))); } /** * 计算折线或者点数组的长度 * @param {Polyline|Array} polyline 折线对象或者点数组 * @returns {Number} 折线或点数组对应的长度 */ GeoUtils.getPolylineDistance = function(polyline){ //检查类型 if(polyline instanceof BMap.Polyline || polyline instanceof Array){ //将polyline统一为数组 var pts; if(polyline instanceof BMap.Polyline){ pts = polyline.getPath(); } else { pts = polyline; } if(pts.length < 2){ //小于2个点，返回0 return 0; } //遍历所有线段将其相加，计算整条线段的长度 var totalDis = 0; for(var i =0; i < pts.length - 1; i++){ var curPt = pts[i]; var nextPt = pts[i + 1] var dis = GeoUtils.getDistance(curPt, nextPt); totalDis += dis; } return totalDis; } else { return 0; } } /** * 计算多边形面或点数组构建图形的面积,注意：坐标类型只能是经纬度，且不适合计算自相交多边形的面积 * @param {Polygon|Array } polygon 多边形面对象或者点数组 * @returns {Number} 多边形面或点数组构成图形的面积 */ GeoUtils.getPolygonArea = function(polygon){ //检查类型 if(!(polygon instanceof BMap.Polygon) && !(polygon instanceof Array)){ return 0; } var pts; if(polygon instanceof BMap.Polygon){ pts = polygon.getPath(); }else{ pts = polygon; } if(pts.length < 3){ //小于3个顶点，不能构建面 return 0; } var totalArea = 0;//初始化总面积 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 = EARTHRADIUS; //6378137.0,WGS84椭球半径 var Count = pts.length; for (var i = 0; i < Count; i++) { if (i == 0) { LowX = pts[Count - 1].lng * Math.PI / 180; LowY = pts[Count - 1].lat * Math.PI / 180; MiddleX = pts[0].lng * Math.PI / 180; MiddleY = pts[0].lat * Math.PI / 180; HighX = pts[1].lng * Math.PI / 180; HighY = pts[1].lat * Math.PI / 180; } else if (i == Count - 1) { LowX = pts[Count - 2].lng * Math.PI / 180; LowY = pts[Count - 2].lat * Math.PI / 180; MiddleX = pts[Count - 1].lng * Math.PI / 180; MiddleY = pts[Count - 1].lat * Math.PI / 180; HighX = pts[0].lng * Math.PI / 180; HighY = pts[0].lat * Math.PI / 180; } else { LowX = pts[i - 1].lng * Math.PI / 180; LowY = pts[i - 1].lat * Math.PI / 180; MiddleX = pts[i].lng * Math.PI / 180; MiddleY = pts[i].lat * Math.PI / 180; HighX = pts[i + 1].lng * Math.PI / 180; HighY = pts[i + 1].lat * Math.PI / 180; } AM = Math.cos(MiddleY) * Math.cos(MiddleX); BM = Math.cos(MiddleY) * Math.sin(MiddleX); CM = Math.sin(MiddleY); AL = Math.cos(LowY) * Math.cos(LowX); BL = Math.cos(LowY) * Math.sin(LowX); CL = Math.sin(LowY); AH = Math.cos(HighY) * Math.cos(HighX); BH = Math.cos(HighY) * Math.sin(HighX); CH = Math.sin(HighY); CoefficientL = (AM * AM + BM * BM + CM * CM) / (AM * AL + BM * BL + CM * CL); CoefficientH = (AM * AM + BM * BM + CM * CM) / (AM * AH + BM * BH + CM * CH); ALtangent = CoefficientL * AL - AM; BLtangent = CoefficientL * BL - BM; CLtangent = CoefficientL * CL - CM; AHtangent = CoefficientH * AH - AM; BHtangent = CoefficientH * BH - BM; CHtangent = CoefficientH * CH - CM; AngleCos = (AHtangent * ALtangent + BHtangent * BLtangent + CHtangent * CLtangent) / (Math.sqrt(AHtangent * AHtangent + BHtangent * BHtangent + CHtangent * CHtangent) * Math.sqrt(ALtangent * ALtangent + BLtangent * BLtangent + CLtangent * CLtangent)); AngleCos = Math.acos(AngleCos); ANormalLine = BHtangent * CLtangent - CHtangent * BLtangent; BNormalLine = 0 - (AHtangent * CLtangent - CHtangent * ALtangent); CNormalLine = AHtangent * BLtangent - BHtangent * ALtangent; if (AM != 0) OrientationValue = ANormalLine / AM; else if (BM != 0) OrientationValue = BNormalLine / BM; else OrientationValue = CNormalLine / CM; if (OrientationValue > 0) { Sum1 += AngleCos; Count1++; } else { Sum2 += AngleCos; Count2++; } } var tempSum1, tempSum2; tempSum1 = Sum1 + (2 * Math.PI * Count2 - Sum2); tempSum2 = (2 * Math.PI * Count1 - Sum1) + Sum2; if (Sum1 > Sum2) { if ((tempSum1 - (Count - 2) * Math.PI) < 1) Sum = tempSum1; else Sum = tempSum2; } else { if ((tempSum2 - (Count - 2) * Math.PI) < 1) Sum = tempSum2; else Sum = tempSum1; } totalArea = (Sum - (Count - 2) * Math.PI) * Radius * Radius; return totalArea; //返回总面积 } })();//闭包结束
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