在做地图相关开发时候，绕不开不同坐标系间的转化，因此我根据查阅相关资料后将不同坐标系间的转换封装到一个GeoTranslate类中，该类转换函数不仅支持Qt/C++调用，同时可在QML中直接调用，配合上QML/Map很方便，我将该类做了个Demo，方便使用者使用，效果如图：

在QML的地图Map中使用高德的路径规划的效果：

使用方法为将 GeoTranslate类添加到工程中，调用转换函数即可

geotranslate.h：

#ifndef GEOTRANSLATE_H
#define GEOTRANSLATE_H

#include <QtMath>
#include <QObject>
#include <QGeoCoordinate>

class GeoTranslate : public QObject
{
public:
    explicit GeoTranslate(QObject *parent = nullptr);

    static constexpr double pi = 3.14159265358979323846;
    static constexpr double a = 6378245.0;
    static constexpr double ee = 0.00669342162296594323;

    Q_INVOKABLE static QGeoCoordinate wgs84ToGcj02(QGeoCoordinate coordinate);
    Q_INVOKABLE static QGeoCoordinate gcj02ToWgs84(QGeoCoordinate coordinate);
    Q_INVOKABLE static QGeoCoordinate wgs84ToGcj02(double lat,double lon);
    Q_INVOKABLE static QGeoCoordinate gcj02ToWgs84(double lat,double lon);

    Q_INVOKABLE static QGeoCoordinate gcj02ToBd09(QGeoCoordinate coordinate);
    Q_INVOKABLE static QGeoCoordinate bd09ToGcj02(QGeoCoordinate coordinate);
    Q_INVOKABLE static QGeoCoordinate gcj02ToBd09(double gg_lat, double gg_lon);
    Q_INVOKABLE static QGeoCoordinate bd09ToGcj02(double bd_lat,double bd_lon);

private:
    static double transformLat(double x,double y);
    static double transformLon(double x,double y);
    static bool outOfChina(double lat,double lon);
    static QGeoCoordinate transform(double lat,double lon);

};

#endif // GEOTRANSLATE_H

 调用方法：

void Widget::on_pushButton_1_clicked()
{
    QGeoCoordinate wgs(ui->lineEditLa_1->text().toDouble(),ui->lineEditLo_1->text().toDouble());
    QGeoCoordinate gcj02 = GeoTranslate::wgs84ToGcj02(wgs);
    ui->lineEditLa_2->setText(QString::number(gcj02.latitude()));
    ui->lineEditLo_2->setText(QString::number(gcj02.longitude()));
}

void Widget::on_pushButton_2_clicked()
{
    QGeoCoordinate gcj02(ui->lineEditLa_3->text().toDouble(),ui->lineEditLo_3->text().toDouble());
    QGeoCoordinate wgs = GeoTranslate::gcj02ToWgs84(gcj02);
    ui->lineEditLa_4->setText(QString::number(wgs.latitude()));
    ui->lineEditLo_4->setText(QString::number(wgs.longitude()));
}

void Widget::on_pushButton_3_clicked()
{
    QGeoCoordinate gcj02(ui->lineEditLa_5->text().toDouble(),ui->lineEditLo_5->text().toDouble());
    QGeoCoordinate bd09 = GeoTranslate::gcj02ToBd09(gcj02);
    ui->lineEditLa_6->setText(QString::number(bd09.latitude()));
    ui->lineEditLo_6->setText(QString::number(bd09.longitude()));
}

void Widget::on_pushButton_4_clicked()
{
    QGeoCoordinate bd09(ui->lineEditLa_7->text().toDouble(),ui->lineEditLo_7->text().toDouble());
    QGeoCoordinate gcj02 = GeoTranslate::bd09ToGcj02(bd09);
    ui->lineEditLa_8->setText(QString::number(gcj02.latitude()));
    ui->lineEditLo_8->setText(QString::number(gcj02.longitude()));
}

 完整Demo（包含geotranslate.h  /  geotranslate.cpp）我上传到CSDN库中，自行下载即可运行：

https://download.csdn.net/download/zjgo007/87966450