/**
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* @fileoverview GeoUtils类提供若干几何算法，用来帮助用户判断点与矩形、
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* 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。
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* 主入口类是<a href="symbols/BMapLib.GeoUtils.html">GeoUtils</a>，
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* 基于Baidu Map API 1.2。
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*
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* @author Baidu Map Api Group
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* @version 1.2
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*/
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/**
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* @namespace BMap的所有library类均放在BMapLib命名空间下
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*/
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var BMapLib = window.BMapLib = BMapLib || {};
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(function() {
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/**
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* 地球半径
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*/
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var EARTHRADIUS = 6370996.81;
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/**
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* @exports GeoUtils as BMapLib.GeoUtils
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*/
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var GeoUtils =
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/**
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* GeoUtils类，静态类，勿需实例化即可使用
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* @class GeoUtils类的<b>入口</b>。
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* 该类提供的都是静态方法，勿需实例化即可使用。
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*/
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BMapLib.GeoUtils = function(){
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}
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/**
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* 判断点是否在矩形内
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* @param {Point} point 点对象
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* @param {Bounds} bounds 矩形边界对象
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* @returns {Boolean} 点在矩形内返回true,否则返回false
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*/
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GeoUtils.isPointInRect = function(point, bounds){
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//检查类型是否正确
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if (!(point instanceof BMap.Point) ||
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!(bounds instanceof BMap.Bounds)) {
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return false;
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}
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var sw = bounds.getSouthWest(); //西南脚点
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var ne = bounds.getNorthEast(); //东北脚点
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return (point.lng >= sw.lng && point.lng <= ne.lng && point.lat >= sw.lat && point.lat <= ne.lat);
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}
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/**
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* 判断点是否在圆形内
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* @param {Point} point 点对象
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* @param {Circle} circle 圆形对象
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* @returns {Boolean} 点在圆形内返回true,否则返回false
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*/
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GeoUtils.isPointInCircle = function(point, circle){
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//检查类型是否正确
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if (!(point instanceof BMap.Point) ||
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!(circle instanceof BMap.Circle)) {
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return false;
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}
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//point与圆心距离小于圆形半径，则点在圆内，否则在圆外
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var c = circle.getCenter();
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var r = circle.getRadius();
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var dis = GeoUtils.getDistance(point, c);
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if(dis <= r){
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return true;
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} else {
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return false;
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}
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}
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/**
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* 判断点是否在折线上
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* @param {Point} point 点对象
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* @param {Polyline} polyline 折线对象
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* @returns {Boolean} 点在折线上返回true,否则返回false
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*/
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GeoUtils.isPointOnPolyline = function(point, polyline){
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//检查类型
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if(!(point instanceof BMap.Point) ||
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!(polyline instanceof BMap.Polyline)){
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return false;
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}
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//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
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var lineBounds = polyline.getBounds();
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if(!this.isPointInRect(point, lineBounds)){
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return false;
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}
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//判断点是否在线段上，设点为Q，线段为P1P2 ，
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//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
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var pts = polyline.getPath();
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for(var i = 0; i < pts.length - 1; i++){
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var curPt = pts[i];
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var nextPt = pts[i + 1];
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//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
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if (point.lng >= Math.min(curPt.lng, nextPt.lng) && point.lng <= Math.max(curPt.lng, nextPt.lng) &&
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point.lat >= Math.min(curPt.lat, nextPt.lat) && point.lat <= Math.max(curPt.lat, nextPt.lat)){
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//判断点是否在直线上公式
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var precision = (curPt.lng - point.lng) * (nextPt.lat - point.lat) -
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(nextPt.lng - point.lng) * (curPt.lat - point.lat);
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if(precision < 2e-10 && precision > -2e-10){//实质判断是否接近0
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return true;
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}
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}
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}
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return false;
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}
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/**
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* 判断点是否多边形内
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* @param {Point} point 点对象
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* @param {Polyline} polygon 多边形对象
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* @returns {Boolean} 点在多边形内返回true,否则返回false
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*/
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GeoUtils.isPointInPolygon = function(point, polygon){
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//检查类型
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if(!(point instanceof BMap.Point) ||
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!(polygon instanceof BMap.Polygon)){
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return false;
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}
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//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
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var polygonBounds = polygon.getBounds();
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if(!this.isPointInRect(point, polygonBounds)){
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return false;
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}
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var pts = polygon.getPath();//获取多边形点
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//下述代码来源：http://paulbourke.net/geometry/insidepoly/，进行了部分修改
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//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
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//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。
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var N = pts.length;
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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
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var intersectCount = 0;//cross points count of x
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var precision = 2e-10; //浮点类型计算时候与0比较时候的容差
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var p1, p2;//neighbour bound vertices
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var p = point; //测试点
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p1 = pts[0];//left vertex
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for(var i = 1; i <= N; ++i){//check all rays
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if(p.equals(p1)){
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return boundOrVertex;//p is an vertex
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}
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p2 = pts[i % N];//right vertex
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if(p.lat < Math.min(p1.lat, p2.lat) || p.lat > Math.max(p1.lat, p2.lat)){//ray is outside of our interests
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p1 = p2;
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continue;//next ray left point
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}
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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)
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if(p.lng <= Math.max(p1.lng, p2.lng)){//x is before of ray
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if(p1.lat == p2.lat && p.lng >= Math.min(p1.lng, p2.lng)){//overlies on a horizontal ray
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return boundOrVertex;
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}
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if(p1.lng == p2.lng){//ray is vertical
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if(p1.lng == p.lng){//overlies on a vertical ray
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return boundOrVertex;
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}else{//before ray
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++intersectCount;
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}
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}else{//cross point on the left side
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var xinters = (p.lat - p1.lat) * (p2.lng - p1.lng) / (p2.lat - p1.lat) + p1.lng;//cross point of lng
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if(Math.abs(p.lng - xinters) < precision){//overlies on a ray
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return boundOrVertex;
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}
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if(p.lng < xinters){//before ray
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++intersectCount;
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}
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}
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}
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}else{//special case when ray is crossing through the vertex
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if(p.lat == p2.lat && p.lng <= p2.lng){//p crossing over p2
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var p3 = pts[(i+1) % N]; //next vertex
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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
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++intersectCount;
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}else{
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intersectCount += 2;
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}
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}
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}
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p1 = p2;//next ray left point
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}
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if(intersectCount % 2 == 0){//偶数在多边形外
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return false;
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} else { //奇数在多边形内
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return true;
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}
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}
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/**
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* 将度转化为弧度
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* @param {degree} Number 度
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* @returns {Number} 弧度
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*/
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GeoUtils.degreeToRad = function(degree){
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return Math.PI * degree/180;
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}
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/**
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* 将弧度转化为度
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* @param {radian} Number 弧度
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* @returns {Number} 度
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*/
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GeoUtils.radToDegree = function(rad){
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return (180 * rad) / Math.PI;
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}
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/**
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* 将v值限定在a,b之间，纬度使用
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*/
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function _getRange(v, a, b){
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if(a != null){
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v = Math.max(v, a);
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}
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if(b != null){
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v = Math.min(v, b);
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}
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return v;
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}
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/**
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* 将v值限定在a,b之间，经度使用
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*/
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function _getLoop(v, a, b){
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while( v > b){
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v -= b - a
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}
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while(v < a){
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v += b - a
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}
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return v;
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}
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/**
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* 计算两点之间的距离,两点坐标必须为经纬度
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* @param {point1} Point 点对象
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* @param {point2} Point 点对象
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* @returns {Number} 两点之间距离，单位为米
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*/
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GeoUtils.getDistance = function(point1, point2){
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//判断类型
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if(!(point1 instanceof BMap.Point) ||
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!(point2 instanceof BMap.Point)){
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return 0;
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}
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point1.lng = _getLoop(point1.lng, -180, 180);
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point1.lat = _getRange(point1.lat, -74, 74);
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point2.lng = _getLoop(point2.lng, -180, 180);
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point2.lat = _getRange(point2.lat, -74, 74);
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var x1, x2, y1, y2;
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x1 = GeoUtils.degreeToRad(point1.lng);
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y1 = GeoUtils.degreeToRad(point1.lat);
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x2 = GeoUtils.degreeToRad(point2.lng);
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y2 = GeoUtils.degreeToRad(point2.lat);
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return EARTHRADIUS * Math.acos((Math.sin(y1) * Math.sin(y2) + Math.cos(y1) * Math.cos(y2) * Math.cos(x2 - x1)));
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}
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/**
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* 计算折线或者点数组的长度
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* @param {Polyline|Array<Point>} polyline 折线对象或者点数组
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* @returns {Number} 折线或点数组对应的长度
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*/
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GeoUtils.getPolylineDistance = function(polyline){
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//检查类型
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if(polyline instanceof BMap.Polyline ||
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polyline instanceof Array){
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//将polyline统一为数组
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var pts;
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if(polyline instanceof BMap.Polyline){
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pts = polyline.getPath();
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} else {
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pts = polyline;
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}
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if(pts.length < 2){//小于2个点，返回0
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return 0;
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}
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//遍历所有线段将其相加，计算整条线段的长度
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var totalDis = 0;
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for(var i =0; i < pts.length - 1; i++){
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var curPt = pts[i];
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var nextPt = pts[i + 1]
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var dis = GeoUtils.getDistance(curPt, nextPt);
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totalDis += dis;
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}
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return totalDis;
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} else {
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return 0;
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}
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}
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/**
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* 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
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* @param {Polygon|Array<Point>} polygon 多边形面对象或者点数组
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* @returns {Number} 多边形面或点数组构成图形的面积
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*/
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GeoUtils.getPolygonArea = function(polygon){
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//检查类型
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if(!(polygon instanceof BMap.Polygon) &&
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!(polygon instanceof Array)){
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return 0;
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}
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var pts;
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if(polygon instanceof BMap.Polygon){
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pts = polygon.getPath();
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}else{
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pts = polygon;
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}
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if(pts.length < 3){//小于3个顶点，不能构建面
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return 0;
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}
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var totalArea = 0;//初始化总面积
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var LowX = 0.0;
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var LowY = 0.0;
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var MiddleX = 0.0;
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var MiddleY = 0.0;
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var HighX = 0.0;
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var HighY = 0.0;
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var AM = 0.0;
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var BM = 0.0;
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var CM = 0.0;
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var AL = 0.0;
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var BL = 0.0;
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var CL = 0.0;
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var AH = 0.0;
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var BH = 0.0;
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var CH = 0.0;
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var CoefficientL = 0.0;
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var CoefficientH = 0.0;
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var ALtangent = 0.0;
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var BLtangent = 0.0;
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var CLtangent = 0.0;
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var AHtangent = 0.0;
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var BHtangent = 0.0;
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var CHtangent = 0.0;
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var ANormalLine = 0.0;
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var BNormalLine = 0.0;
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var CNormalLine = 0.0;
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var OrientationValue = 0.0;
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var AngleCos = 0.0;
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var Sum1 = 0.0;
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var Sum2 = 0.0;
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var Count2 = 0;
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var Count1 = 0;
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var Sum = 0.0;
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var Radius = EARTHRADIUS; //6378137.0,WGS84椭球半径
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var Count = pts.length;
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for (var i = 0; i < Count; i++) {
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if (i == 0) {
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LowX = pts[Count - 1].lng * Math.PI / 180;
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LowY = pts[Count - 1].lat * Math.PI / 180;
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MiddleX = pts[0].lng * Math.PI / 180;
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MiddleY = pts[0].lat * Math.PI / 180;
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HighX = pts[1].lng * Math.PI / 180;
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HighY = pts[1].lat * Math.PI / 180;
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}
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else if (i == Count - 1) {
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LowX = pts[Count - 2].lng * Math.PI / 180;
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LowY = pts[Count - 2].lat * Math.PI / 180;
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MiddleX = pts[Count - 1].lng * Math.PI / 180;
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MiddleY = pts[Count - 1].lat * Math.PI / 180;
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HighX = pts[0].lng * Math.PI / 180;
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HighY = pts[0].lat * Math.PI / 180;
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}
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else {
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LowX = pts[i - 1].lng * Math.PI / 180;
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LowY = pts[i - 1].lat * Math.PI / 180;
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MiddleX = pts[i].lng * Math.PI / 180;
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MiddleY = pts[i].lat * Math.PI / 180;
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HighX = pts[i + 1].lng * Math.PI / 180;
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HighY = pts[i + 1].lat * Math.PI / 180;
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}
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AM = Math.cos(MiddleY) * Math.cos(MiddleX);
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BM = Math.cos(MiddleY) * Math.sin(MiddleX);
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CM = Math.sin(MiddleY);
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AL = Math.cos(LowY) * Math.cos(LowX);
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BL = Math.cos(LowY) * Math.sin(LowX);
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CL = Math.sin(LowY);
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AH = Math.cos(HighY) * Math.cos(HighX);
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BH = Math.cos(HighY) * Math.sin(HighX);
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CH = Math.sin(HighY);
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CoefficientL = (AM * AM + BM * BM + CM * CM) / (AM * AL + BM * BL + CM * CL);
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CoefficientH = (AM * AM + BM * BM + CM * CM) / (AM * AH + BM * BH + CM * CH);
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ALtangent = CoefficientL * AL - AM;
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BLtangent = CoefficientL * BL - BM;
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CLtangent = CoefficientL * CL - CM;
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AHtangent = CoefficientH * AH - AM;
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BHtangent = CoefficientH * BH - BM;
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CHtangent = CoefficientH * CH - CM;
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AngleCos = (AHtangent * ALtangent + BHtangent * BLtangent + CHtangent * CLtangent) / (Math.sqrt(AHtangent * AHtangent + BHtangent * BHtangent + CHtangent * CHtangent) * Math.sqrt(ALtangent * ALtangent + BLtangent * BLtangent + CLtangent * CLtangent));
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AngleCos = Math.acos(AngleCos);
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ANormalLine = BHtangent * CLtangent - CHtangent * BLtangent;
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BNormalLine = 0 - (AHtangent * CLtangent - CHtangent * ALtangent);
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CNormalLine = AHtangent * BLtangent - BHtangent * ALtangent;
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if (AM != 0)
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OrientationValue = ANormalLine / AM;
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else if (BM != 0)
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OrientationValue = BNormalLine / BM;
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else
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OrientationValue = CNormalLine / CM;
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if (OrientationValue > 0) {
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Sum1 += AngleCos;
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Count1++;
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}
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else {
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Sum2 += AngleCos;
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Count2++;
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}
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}
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var tempSum1, tempSum2;
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tempSum1 = Sum1 + (2 * Math.PI * Count2 - Sum2);
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tempSum2 = (2 * Math.PI * Count1 - Sum1) + Sum2;
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if (Sum1 > Sum2) {
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if ((tempSum1 - (Count - 2) * Math.PI) < 1)
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Sum = tempSum1;
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else
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Sum = tempSum2;
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}
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else {
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if ((tempSum2 - (Count - 2) * Math.PI) < 1)
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Sum = tempSum2;
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else
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Sum = tempSum1;
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}
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totalArea = (Sum - (Count - 2) * Math.PI) * Radius * Radius;
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return totalArea; //返回总面积
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}
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})();//闭包结束
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