36.QT地图

• widget.h

   #ifndef MAPWIDGET_H
   #define MAPWIDGET_H
  
   #include <QGraphicsView>
   #include <QLabel>
   #include <QMouseEvent>
  
   class MapWidget : public QGraphicsView
   {
       Q_OBJECT
   public:
       MapWidget();
  
       void readMap();                         //读取地图信息
       QPointF mapToMap(QPointF);              //用于实现场景坐标系与地图坐标之间的映射，以获得某点的经纬度值
  
   public slots:
       void slotZoom(int);
  
   protected:
       void drawBackground(QPainter *painter, const QRectF &rect);         //完成地图显示的功能
       void mouseMoveEvent(QMouseEvent *event);                            //鼠标移动功能
  
   private:
       QPixmap map;        //地图
       qreal zoom;         //大小
       QLabel *viewCoord;  //标签
       QLabel *sceneCoord;
       QLabel *mapCoord;
       double x1,y1;
       double x2,y2;
   };
  
   #endif // MAPWIDGET_H

• widget.cpp

   #include "widget.h"
   #include <QSlider>
   #include <QGridLayout>
   #include <QFile>
   #include <QTextStream>
   #include <QGraphicsScene>
   #include <math.h>
  
   MapWidget::MapWidget()
   {
       readMap();                                    //读取地图信息
  
       zoom=;
  
       int width = map.width();
       int height = map.height();
       QGraphicsScene *scene = new QGraphicsScene(this);
       scene->setSceneRect(-width/,-height/,width,height);
       setScene(scene);
       setCacheMode(CacheBackground);
  
       //用于地图缩放的滑动条
       QSlider *slider = new QSlider;
       slider->setOrientation(Qt::Vertical);
       slider->setRange(,);
       slider->setTickInterval();
       slider->setValue();
       connect(slider,SIGNAL(valueChanged(int)),this,SLOT(slotZoom(int)));
  
       QLabel *zoominLabel = new QLabel;
       zoominLabel->setScaledContents(true);
       zoominLabel->setPixmap(QPixmap("zoomin.png"));
  
       QLabel *zoomoutLabel = new QLabel;
       zoomoutLabel->setScaledContents(true);
       zoomoutLabel->setPixmap(QPixmap("zoomout.png"));
  
       //坐标值显示区
       QLabel *label1 = new QLabel(tr("GraphicsView:"));
       viewCoord = new QLabel;
       QLabel *label2 = new QLabel(tr("GraphicsScene:"));
       sceneCoord = new QLabel;
       QLabel *label3 = new QLabel(tr("map:"));
       mapCoord = new QLabel;
  
       //坐标显示区布局
       QGridLayout *gridLayout = new QGridLayout;
       gridLayout->addWidget(label1,,);
       gridLayout->addWidget(viewCoord,,);
       gridLayout->addWidget(label2,,);
       gridLayout->addWidget(sceneCoord,,);
       gridLayout->addWidget(label3,,);
       gridLayout->addWidget(mapCoord,,);
       gridLayout->setSizeConstraint(QLayout::SetFixedSize);
  
       QFrame *coordFrame = new QFrame;
       coordFrame->setLayout(gridLayout);
  
       //缩放控制子布局
       QVBoxLayout *zoomLayout = new QVBoxLayout;
       zoomLayout->addWidget(zoominLabel);
       zoomLayout->addWidget(slider);
       zoomLayout->addWidget(zoomoutLabel);
  
       //坐标显示区域布局
       QVBoxLayout *coordLayout = new QVBoxLayout;
       coordLayout->addWidget(coordFrame);
       coordLayout->addStretch();
  
       //主布局
       QHBoxLayout *mainLayout = new QHBoxLayout;
       //滑动
       mainLayout->addLayout(zoomLayout);
       //坐标
       mainLayout->addLayout(coordLayout);
       mainLayout->addStretch();
       mainLayout->setMargin();
       mainLayout->setSpacing();
       setLayout(mainLayout);
  
       setWindowTitle("Map Widget");
       setMinimumSize(,);
   }
  
   void MapWidget::readMap()            //读取地图信息
   {
       QString mapName;
       QFile mapFile("maps.txt");
       //打开文件
       int ok = mapFile.open(QIODevice::ReadOnly);
       if(ok)
       {
           QTextStream ts(&mapFile);
           if(!ts.atEnd())
           {
               ts>>mapName;
               ts>>x1>>y1>>x2>>y2;
           }
       }
       //载入地图
       map.load(mapName);
   }
  
   void MapWidget::slotZoom(int value)       //地图缩放与放大
   {
       qreal s;
       if(value>zoom)                         //放大
       {
           s=pow(1.01,(value-zoom));
       }
       else                                 //缩小
       {
           s=pow(/1.01,(zoom-value));
       }
       scale(s,s);//放大缩小
      // rotate(s);
       zoom = value;
   }
  
   //绘制背景
   void MapWidget::drawBackground(QPainter *painter, const QRectF &rect)
   {
       painter->drawPixmap(int(sceneRect().left()),int(sceneRect().top()), map);//绘图
   }
  
   void MapWidget::mouseMoveEvent(QMouseEvent *event)
   {
       //QGraphicsView 坐标
       QPoint viewPoint = event->pos();
       viewCoord->setText(QString::number(viewPoint.x())+","+QString::number(viewPoint.y()));
  
       //QGraphicsScene 坐标
       QPointF scenePoint = mapToScene(viewPoint);
       sceneCoord->setText(QString::number(scenePoint.x())+","+QString::number(scenePoint.y()));
  
       //地图坐标(经、纬度值)
       QPointF latLon = mapToMap(scenePoint);
       mapCoord->setText(QString::number(latLon.x())+","+QString::number(latLon.y()));
   }
  
   //用于实现场景坐标系与地图坐标之间的映射，以获得某点的经纬度值
   QPointF MapWidget::mapToMap(QPointF p)
   {
       QPointF latLon;
       qreal w =sceneRect().width();
       qreal h =sceneRect().height();
  
       qreal lon = y1-((h/+p.y())*abs(y1-y2)/h);
       qreal lat = x1+((w/+p.x())*abs(x1-x2)/w);
  
       latLon.setX(lat);
       latLon.setY(lon);
  
       return latLon;
   }

• main.c

   #include "widget.h"
   #include <QApplication>
  
   int main(int argc, char *argv[])
   {
       QApplication a(argc, argv);
       //设置字体
       QFont font("ARPL KaitiM GB",);
       font.setBold(true);
       a.setFont(font);
  
       //显示
       MapWidget w;
       w.show();
  
       return a.exec();
   }