add map about

xuwenmin · xuwenmin · commit 1cac699c56f9 · 2014-08-26T10:52:49.000+08:00
diff --git a/_posts/JavaScript/2014-08-26-GPS坐标转换成GCJ-02坐标的JS代码.md b/_posts/JavaScript/2014-08-26-GPS坐标转换成GCJ-02坐标的JS代码.md
@@ -0,0 +1,88 @@
+---
+layout: post
+category : JavaScript
+tagline: ""
+tags : [地图坐标转换,GCJ-02]
+---
+{% include JB/setup %}
+
+由于最近在开发相关地图应用,所以不可必免的就会遇到`GPS`坐标(`WGS-84`)转换成国家测绘局标准要求的`GCJ-02`(所谓的火星坐标)
+
+关于`WGS-84`与`GCJ-02`可以参照这篇文章,<a href="http://bbs.amap.com/thread-18617-1-2.html" target="_blank">坐标转换、偏移</a>.
+
+下面的代码摘直网上,特收藏下
+
+```js
+
+//World Geodetic System ==> Mars Geodetic System
+//translate from https://on4wp7.codeplex.com/SourceControl/changeset/view/21483#353936
+var WGS84_to_GCJ02 = function() {}
+
+WGS84_to_GCJ02.prototype.a = 6378245.0;
+WGS84_to_GCJ02.prototype.ee = 0.00669342162296594323;
+WGS84_to_GCJ02.prototype.transform = function(wgLat, wgLon) {
+
+    if (this.outOfChina(wgLat, wgLon)) {
+        return [wgLat, wgLon];
+    }
+
+    dLat = this.transformLat(wgLon - 105.0, wgLat - 35.0);
+    dLon = this.transformLon(wgLon - 105.0, wgLat - 35.0);
+    radLat = wgLat / 180.0 * Math.PI;
+    magic = Math.sin(radLat);
+    magic = 1 - this.ee * magic * magic;
+    sqrtMagic = Math.sqrt(magic);
+    dLat = (dLat * 180.0) / ((this.a * (1 - this.ee)) / (magic * sqrtMagic) * Math.PI);
+    dLon = (dLon * 180.0) / (this.a / sqrtMagic * Math.cos(radLat) * Math.PI);
+    mgLat = wgLat + dLat;
+    mgLon = wgLon + dLon;
+
+    return [mgLat, mgLon];
+
+};
+
+WGS84_to_GCJ02.prototype.outOfChina = function(lat, lon) {
+
+    if (lon < 72.004 || lon > 137.8347)
+        return true;
+    if (lat < 0.8293 || lat > 55.8271)
+        return true;
+
+    return false;
+
+};
+
+WGS84_to_GCJ02.prototype.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 * Math.PI) + 20.0 * Math.sin(2.0 * x * Math.PI)) * 2.0 / 3.0;
+    ret += (20.0 * Math.sin(y * Math.PI) + 40.0 * Math.sin(y / 3.0 * Math.PI)) * 2.0 / 3.0;
+    ret += (160.0 * Math.sin(y / 12.0 * Math.PI) + 320 * Math.sin(y * Math.PI / 30.0)) * 2.0 / 3.0;
+
+    return ret;
+
+};
+
+WGS84_to_GCJ02.prototype.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 * Math.PI) + 20.0 * Math.sin(2.0 * x * Math.PI)) * 2.0 / 3.0;
+    ret += (20.0 * Math.sin(x * Math.PI) + 40.0 * Math.sin(x / 3.0 * Math.PI)) * 2.0 / 3.0;
+    ret += (150.0 * Math.sin(x / 12.0 * Math.PI) + 300.0 * Math.sin(x / 30.0 * Math.PI)) * 2.0 / 3.0;
+
+    return ret;
+
+};
+
+```
+
+使用例子如下:
+
+```js
+
+new WGS84_to_GCJ02().transform(31.283814, 121.502191) 
+// -> [31.28181188043995, 121.50661885748906] （该坐标是上海同济大学）
+
+```
+
+最后附上一个在线转换接口,<a href="http://www.zdoz.net/apiList.html" target="_blank">在线转换坐标接口</a>
