TransGPS.js
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/** GCJ WGS BD 等坐标转换算法，从 TransGPS.java 代码转换而来*/
var TransGPS = (function(){
var pi = 3.14159265358979324
,a = 6378245.0
,ee = 0.00669342162296594323;
function outOfChina(lat, lon){
if (lon < 72.004 || lon > 137.8347)
return 1;
if (lat < 0.8293 || lat > 55.8271)
return 1;
return 0;
}
function transformLat(x, y){
var ret = -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * Math.sqrt(x > 0 ? x : -x);
ret += (20.0 * Math.sin(6.0 * x * pi) + 20.0 * Math.sin(2.0 * x * pi)) * 2.0 / 3.0;
ret += (20.0 * Math.sin(y * pi) + 40.0 * Math.sin(y / 3.0 * pi)) * 2.0 / 3.0;
ret += (160.0 * Math.sin(y / 12.0 * pi) + 320 * Math.sin(y * pi / 30.0)) * 2.0 / 3.0;
return ret;
}
function transformLon(x, y){
var ret = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * Math.sqrt(x > 0 ? x : -x);
ret += (20.0 * Math.sin(6.0 * x * pi) + 20.0 * Math.sin(2.0 * x * pi)) * 2.0 / 3.0;
ret += (20.0 * Math.sin(x * pi) + 40.0 * Math.sin(x / 3.0 * pi)) * 2.0 / 3.0;
ret += (150.0 * Math.sin(x / 12.0 * pi) + 300.0 * Math.sin(x / 30.0 * pi)) * 2.0 / 3.0;
return ret;
}
function transformFromWGSToGCJ(lat, lng){
var mgLoc = {};
if(1 == outOfChina(lat, lng)){
mgLoc = {lat: lat, lng: lng};
return mgLoc;
}
var dLat = transformLat(lng - 105.0, lat - 35.0);
var dLon = transformLon(lng - 105.0, lat - 35.0);
var radLat = lat / 180.0 * pi;
var magic = Math.sin(radLat);
magic = 1 - ee * magic * magic;
var sqrtMagic = Math.sqrt(magic);
dLat = (dLat * 180.0) / ((a * (1 - ee)) / (magic * sqrtMagic) * pi);
dLon = (dLon * 180.0) / (a / sqrtMagic * Math.cos(radLat) * pi);
mgLoc['lat'] = lat + dLat;
mgLoc['lng'] = lng + dLon;
return mgLoc;
}
function transformFromGCJToWGS(lat, lng){
var wgLoc = {lat: lat, lng: lng}
,currGcLoc = {}, dLoc = {};
while (true) {
currGcLoc = transformFromWGSToGCJ(lat, lng);
dLoc.lat = lat - currGcLoc.lat;
dLoc.lng = lng - currGcLoc.lng;
if (Math.abs(dLoc.lat) < 1e-7 && Math.abs(dLoc.lng) < 1e-7) {
return wgLoc;
}
wgLoc.lat += dLoc.lat;
wgLoc.lng += dLoc.lng;
}
}
var x_pi = 3.14159265358979324 * 3000.0 / 180.0;
function bd_encrypt(lat, lng){
var x = lng, y = lat;
var z = Math.sqrt(x * x + y * y) + 0.00002 * Math.sin(y * x_pi);
var theta = Math.atan2(y, x) + 0.000003 * Math.cos(x * x_pi);
return {lng: z * Math.cos(theta) + 0.0065, lat: z * Math.sin(theta) + 0.006};
}
function bd_decrypt(lat, lng){
var x = bdLoc.lng - 0.0065, y = bdLoc.lat - 0.006;
var z = Math.sqrt(x * x + y * y) - 0.00002 * Math.sin(y * x_pi);
var theta = Math.atan2(y, x) - 0.000003 * Math.cos(x * x_pi);
return {lng: z * Math.cos(theta), lat: z * Math.sin(theta)};
}
var transGPS = {
wgsToBD: function(lat, lng){
var gcj = transformFromWGSToGCJ(lat, lng);
return bd_encrypt(gcj.lat, gcj.lng);
},
transformFromWGSToGCJ: transformFromWGSToGCJ
}
return transGPS;
})();