var GPS ={

PI :3.14159265358979324,

x_pi :3.14159265358979324 * 3000.0 / 180.0,

delta :function(lat, lon) {//Krasovsky 1940

// //a = 6378245.0, 1/f = 298.3

//b = a * (1 - f)

//ee = (a^2 - b^2) / a^2;

var a = 6378245.0; //a: 卫星椭球坐标投影到平面地图坐标系的投影因子。

var ee = 0.00669342162296594323; //ee: 椭球的偏心率。

var dLat = this.transformLat(lon - 105.0, lat - 35.0);var dLon = this.transformLon(lon - 105.0, lat - 35.0);var radLat = lat / 180.0 * this.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) * this.PI);

dLon= (dLon * 180.0) / (a / sqrtMagic * Math.cos(radLat) * this.PI);return {'lat': dLat, 'lon': dLon};

},//WGS-84 to GCJ-02

gcj_encrypt : function(wgsLat, wgsLon) {if (this.outOfChina(wgsLat, wgsLon))return {'lat': wgsLat, 'lon': wgsLon};var d = this.delta(wgsLat, wgsLon);return {'lat' : wgsLat + d.lat,'lon' : wgsLon +d.lon};

},//GCJ-02 to WGS-84

gcj_decrypt : function(gcjLat, gcjLon) {if (this.outOfChina(gcjLat, gcjLon))return {'lat': gcjLat, 'lon': gcjLon};var d = this.delta(gcjLat, gcjLon);return {'lat': gcjLat - d.lat, 'lon': gcjLon -d.lon};

},//GCJ-02 to WGS-84 exactly

gcj_decrypt_exact : function(gcjLat, gcjLon) {var initDelta = 0.01;var threshold = 0.000000001;var dLat = initDelta, dLon =initDelta;var mLat = gcjLat - dLat, mLon = gcjLon -dLon;var pLat = gcjLat + dLat, pLon = gcjLon +dLon;var wgsLat, wgsLon, i = 0;while (1) {

wgsLat= (mLat + pLat) / 2;

wgsLon= (mLon + pLon) / 2;var tmp = this.gcj_encrypt(wgsLat, wgsLon)

dLat= tmp.lat -gcjLat;

dLon= tmp.lon -gcjLon;if ((Math.abs(dLat) < threshold) && (Math.abs(dLon) 0) pLat = wgsLat; else mLat =wgsLat;if (dLon > 0) pLon = wgsLon; else mLon =wgsLon;if (++i > 10000) break;

}//console.log(i);

return {'lat': wgsLat, 'lon': wgsLon};

},//GCJ-02 to BD-09

bd_encrypt : function(gcjLat, gcjLon) {var x = gcjLon, y =gcjLat;var z = Math.sqrt(x * x + y * y) + 0.00002 * Math.sin(y * this.x_pi);var theta = Math.atan2(y, x) + 0.000003 * Math.cos(x * this.x_pi);

bdLon= z * Math.cos(theta) + 0.0065;

bdLat= z * Math.sin(theta) + 0.006;return {'lat' : bdLat,'lon': bdLon};

},//BD-09 to GCJ-02

bd_decrypt : function(bdLat, bdLon) {var x = bdLon - 0.0065, y = bdLat - 0.006;var z = Math.sqrt(x * x + y * y) - 0.00002 * Math.sin(y * this.x_pi);var theta = Math.atan2(y, x) - 0.000003 * Math.cos(x * this.x_pi);var gcjLon = z *Math.cos(theta);var gcjLat = z *Math.sin(theta);return {'lat' : gcjLat, 'lon': gcjLon};

},//WGS-84 to Web mercator

//mercatorLat -> y mercatorLon -> x

mercator_encrypt : function(wgsLat, wgsLon) {var x = wgsLon * 20037508.34 / 180.;var y = Math.log(Math.tan((90. + wgsLat) * this.PI / 360.)) / (this.PI / 180.);

y= y * 20037508.34 / 180.;return {'lat' : y, 'lon': x};/*if ((Math.abs(wgsLon) > 180 || Math.abs(wgsLat) > 90))

return null;

var x = 6378137.0 * wgsLon * 0.017453292519943295;

var a = wgsLat * 0.017453292519943295;

var y = 3189068.5 * Math.log((1.0 + Math.sin(a)) / (1.0 - Math.sin(a)));

return {'lat' : y, 'lon' : x};

//*/},//Web mercator to WGS-84

//mercatorLat -> y mercatorLon -> x

mercator_decrypt : function(mercatorLat, mercatorLon) {var x = mercatorLon / 20037508.34 * 180.;var y = mercatorLat / 20037508.34 * 180.;

y= 180 / this.PI * (2 * Math.atan(Math.exp(y * this.PI / 180.)) - this.PI / 2);return {'lat' : y, 'lon': x};/*if (Math.abs(mercatorLon) < 180 && Math.abs(mercatorLat) < 90)

return null;

if ((Math.abs(mercatorLon) > 20037508.3427892) || (Math.abs(mercatorLat) > 20037508.3427892))

return null;

var a = mercatorLon / 6378137.0 * 57.295779513082323;

var x = a - (Math.floor(((a + 180.0) / 360.0)) * 360.0);

var y = (1.5707963267948966 - (2.0 * Math.atan(Math.exp((-1.0 * mercatorLat) / 6378137.0)))) * 57.295779513082323;

return {'lat' : y, 'lon' : x};

//*/},//two point's distance

distance : function(latA, lonA, latB, lonB) {var earthR = 6371000.;var x = Math.cos(latA * this.PI / 180.) * Math.cos(latB * this.PI / 180.) * Math.cos((lonA - lonB) * this.PI / 180);var y = Math.sin(latA * this.PI / 180.) * Math.sin(latB * this.PI / 180.);var s = x +y;if (s > 1) s = 1;if (s < -1) s = -1;var alpha =Math.acos(s);var distance = alpha *earthR;returndistance;

},

outOfChina :function(lat, lon) {if (lon < 72.004 || lon > 137.8347)return true;if (lat < 0.8293 || lat > 55.8271)return true;return false;

},

transformLat :function(x, y) {var ret = -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y + 0.2 *Math.sqrt(Math.abs(x));

ret+= (20.0 * Math.sin(6.0 * x * this.PI) + 20.0 * Math.sin(2.0 * x * this.PI)) * 2.0 / 3.0;

ret+= (20.0 * Math.sin(y * this.PI) + 40.0 * Math.sin(y / 3.0 * this.PI)) * 2.0 / 3.0;

ret+= (160.0 * Math.sin(y / 12.0 * this.PI) + 320 * Math.sin(y * this.PI / 30.0)) * 2.0 / 3.0;returnret;

},

transformLon :function(x, y) {var ret = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 *Math.sqrt(Math.abs(x));

ret+= (20.0 * Math.sin(6.0 * x * this.PI) + 20.0 * Math.sin(2.0 * x * this.PI)) * 2.0 / 3.0;

ret+= (20.0 * Math.sin(x * this.PI) + 40.0 * Math.sin(x / 3.0 * this.PI)) * 2.0 / 3.0;

ret+= (150.0 * Math.sin(x / 12.0 * this.PI) + 300.0 * Math.sin(x / 30.0 * this.PI)) * 2.0 / 3.0;returnret;

}

};