关于WGS84，GCJ02和BD09坐标在QT下的互相转换

首先先解释一下这3个坐标系的问题

WGS84坐标系：即地球坐标系，国际上通用的坐标系。设备一般包含GPS芯片或者北斗芯片获取的经纬度为WGS84地理坐标系, 

谷歌地图（主要是Google Earth）采用的是WGS84地理坐标系（中国范围除外）; 

GCJ02坐标系：即火星坐标系，是由中国国家测绘局制订的地理信息系统的坐标系统。由WGS84坐标系经加密后的坐标系。 

谷歌中国地图（主要是Google Map中）和高德地图采用的是GCJ02地理坐标系; 

BD09坐标系：即百度坐标系，GCJ02坐标系经加密后的坐标系; 

widget.h

#ifndef WIDGET_H#define WIDGET_H#include <QWidget>#include <math.h>#include <QDebug>namespace Ui {class Widget;}class Widget : public QWidget{    Q_OBJECTpublic:    explicit Widget(QWidget *parent = 0);    ~Widget();private:    Ui::Widget *ui;    double transformLat(double x, double y);    double transformLon(double x, double y);    void Wgs84_Gcj02(double wgs_lat, double wgs_lon);    void Gcj02_Bd09(double gcj_lat, double gcj_lon);    void Bd09_Gcj02(double bd_lat, double bd_lon);    void Wgs84_Bd09(double wgs_lat, double wgs_lon);    bool outOfChina(double lat, double lon);};#endif // WIDGET_H

widget.cpp

#include "widget.h"#include "ui_widget.h"static double pi = 3.1415926535897932384626;static double a = 6378245.0;static double ee = 0.00669342162296594323;Widget::Widget(QWidget *parent) :    QWidget(parent),    ui(new Ui::Widget){    ui->setupUi(this);}Widget::~Widget(){    delete ui;}/* * WGS-84 to GCJ-02 */void Widget::Wgs84_Gcj02(double wgs_lat, double wgs_lon){    if (outOfChina(wgs_lat, wgs_lon))    {        qDebug() << "Error";    }    double dLat = transformLat(wgs_lon - 105.0, wgs_lat - 35.0);    double dLon = transformLon(wgs_lon - 105.0, wgs_lat - 35.0);    double radLat = wgs_lat / 180.0 * pi;    double magic = sin(radLat);    magic = 1 - ee * magic * magic;    double sqrtMagic = sqrt(magic);    dLat = (dLat * 180.0) / ((a * (1 - ee)) / (magic * sqrtMagic) * pi);    dLon = (dLon * 180.0) / (a / sqrtMagic * cos(radLat) * pi);    double mgLat = wgs_lat + dLat;    double mgLon = wgs_lon + dLon;}/* * GCJ-02 to BD-09 */void Widget::Gcj02_Bd09(double gcj_lat, double gcj_lon){    double x = gcj_lon, y = gcj_lat;    double z = sqrt(x * x + y * y) + 0.00002 * sin(y * pi);    double theta = atan2(y, x) + 0.000003 * cos(x * pi);    double bd_lon = z * cos(theta) + 0.0065;    double bd_lat = z * sin(theta) + 0.006;}/** * BD-09 to GCJ-02 */void Widget::Bd09_Gcj02(double bd_lat, double bd_lon){    double x = bd_lon - 0.0065, y = bd_lat - 0.006;    double z = sqrt(x * x + y * y) - 0.00002 * sin(y * pi);    double theta = atan2(y, x) - 0.000003 * cos(x * pi);    double gcj_lon = z * cos(theta);    double gcj_lat = z * sin(theta);}/** * WGS-84 to BD-09 */void Widget::Wgs84_Bd09(double wgs_lat, double wgs_lon){    //WGS84_GCJ02    double dLat = transformLat(wgs_lon - 105.0, wgs_lat - 35.0);    double dLon = transformLon(wgs_lon - 105.0, wgs_lat - 35.0);    double radLat = wgs_lat / 180.0 * pi;    double magic = sin(radLat);    magic = 1 - ee * magic * magic;    double sqrtMagic = sqrt(magic);    dLat = (dLat * 180.0) / ((a * (1 - ee)) / (magic * sqrtMagic) * pi);    dLon = (dLon * 180.0) / (a / sqrtMagic * cos(radLat) * pi);    double gcj_lat = wgs_lat + dLat;    double gcj_lon = wgs_lon + dLon;    //GCJ02_BD09    double x = gcj_lon, y = gcj_lat;    double z = sqrt(x * x + y * y) + 0.00002 * sin(y * pi);    double theta = atan2(y, x) + 0.000003 * cos(x * pi);    double bd_lon = z * cos(theta) + 0.0065;    double bd_lat = z * sin(theta) + 0.006;}bool Widget::outOfChina(double lat, double lon){    if (lon < 72.004 || lon > 137.8347)        return true;    if (lat < 0.8293 || lat > 55.8271)        return true;    return false;}double Widget::transformLat(double x, double y){    double ret = -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * sqrt(abs(x));    ret += (20.0 * sin(6.0 * x * pi) + 20.0 * sin(2.0 * x * pi)) * 2.0 / 3.0;    ret += (20.0 * sin(y * pi) + 40.0 * sin(y / 3.0 * pi)) * 2.0 / 3.0;    ret += (160.0 * sin(y / 12.0 * pi) + 320 * sin(y * pi / 30.0)) * 2.0 / 3.0;    return ret;}double Widget::transformLon(double x, double y){    double ret = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * sqrt(abs(x));    ret += (20.0 * sin(6.0 * x * pi) + 20.0 * sin(2.0 * x * pi)) * 2.0 / 3.0;    ret += (20.0 * sin(x * pi) + 40.0 * sin(x / 3.0 * pi)) * 2.0 / 3.0;    ret += (150.0 * sin(x / 12.0 * pi) + 300.0 * sin(x / 30.0 * pi)) * 2.0 / 3.0;    return ret;}

这样利用以下几个函数就可以转换各个坐标系的坐标

Wgs84_Gcj02(double wgs_lat, double wgs_lon);

Gcj02_Bd09(double gcj_lat, double gcj_lon);

Bd09_Gcj02(double bd_lat, double bd_lon);

Wgs84_Bd09(double wgs_lat, double wgs_lon);