如何通過gps數據計算qt移動速度？

Question

如何通過在qt中使用gps數據來獲得我的速度和距離？ 我有這樣的課，也許是任何標準的方法？

#include "mainwindow.h" 
#include "ui_mainwindow.h" 
#include "quitdiallog.h" 
#include <QGeoCoordinate> 
#include <QDebug> 
#include <QtGui/QMessageBox> 
#include <QList> 
MainWindow::MainWindow(QWidget *parent) : 
    QMainWindow(parent), 
    ui(new Ui::MainWindow) 
{ 
    setWindowTitle("Мой кОмпаС"); 
    ui->setupUi(this); 
    startGPS(); 

} 

MainWindow::~MainWindow() 
{ 
    delete ui; 
} 
void MainWindow::startGPS() 
{ 
    // Obtain the location data source if it is not obtained already 
    if (!locationDataSource) 
    { 
     locationDataSource = 
       QGeoPositionInfoSource::createDefaultSource(this); 
     if (locationDataSource) 
     { 
      // Whenever the location data source signals that the current 
      // position is updated, the positionUpdated function is called. 
      QObject::connect(locationDataSource, 
          SIGNAL(positionUpdated(QGeoPositionInfo)), 
          this, 
          SLOT(positionUpdated(QGeoPositionInfo))); 
      // Start listening for position updates 
        locationDataSource->setUpdateInterval(200); 
      locationDataSource->startUpdates(); 
     } else { 
      // Not able to obtain the location data source 
      // TODO: Error handling 
     } 
    } else { 
     // Start listening for position updates 
     locationDataSource->setUpdateInterval(5000); 
     locationDataSource->startUpdates(); 
    } 
} 

void MainWindow::positionUpdated(QGeoPositionInfo geoPositionInfo) 
{ 
    if (geoPositionInfo.isValid()) 
    { 
     //locationDataSource->stopUpdates(); 
     QGeoCoordinate geoCoordinate = geoPositionInfo.coordinate(); 
     this->latitude = geoCoordinate.latitude(); 
     this->longitude = geoCoordinate.longitude(); 
     this->altitude=geoCoordinate.altitude(); 
    ui->label->setNum(latitude); 
    ui->label_2->setNum(longitude); 
    } 
} 



void MainWindow::on_pushButton_clicked() 
{ 
    ui->label_3->setNum(latitude); 
    qDebug()<<latitude<<" "<<longitude<<" "<<altitude; 
} 

void MainWindow::on_pushButton_4_clicked() 
{ 
    QuitDiallog *qi=new QuitDiallog; 
    this->hide(); 
    qi->show(); 
} 

如何獲得速度？

Answer 1

首先我會做source->setPreferredPositioningMethods(QGeoPositionInfoSource::AllPositioningMethods);

地面速度可以獲取的（理論上）由geoPositionInfo.attribute(QGeoPositionInfo::GroundSpeed)

不過可以肯定的geoPositionInfo.hasAttribute(QGeoPositionInfo::GroundSpeed) == true AFAIK有幾個移動設備的一些問題與地面速度。