Second Lecture on qgis Development

Document directory

• Step 1: Create a QT application project named qgis2. The solution file is as follows:
• Step 2: design the UI
• Step 3: Modify the qgis2.h File
• Step 4: Modify the qgis2.cpp File
• Step 5: Modify the main. cpp File
• Step 6: The running result is as follows:

Step 1: Create a QT application project named qgis2. The solution file is as follows:

Step 2: design the UI

(1) double-click the qgis2.ui file to bring up the qtdesigner and add the corresponding menu (corresponding action name), as shown in

(2) drag a qframe container (used to include qgsmapcanvas) into the centralwidget in the center of the panel and name it framemap;

(3) In qtdesigner, click Save to exit.

(4) In the project solution, click "qgis2.ui" and click "compile" to regenerate the file "ui_qgis2.h ".

Step 3: Modify the qgis2.h File

(PS: There is a ui_qgis2.h file in generated files. This file is automatically generated by the qgis2.ui file and does not need to be modified. If this type is required, use it as UI: qgis2class, as shown in the following code)

The modified qigs2.h file is as follows:

#ifndef QGIS2_H#define QGIS2_H#include <QtGui/QMainWindow>#include "ui_qgis2.h"#include <qgsapplication.h>#include <qgsproviderregistry.h>#include <qgssinglesymbolrenderer.h>#include <qgsmapcanvas.h>#include <qgsvectorlayer.h>#include <qgsmaptool.h>#include <QtGui/QVBoxLayout>#include <qgsmaplayerregistry.h>#include <QtGui/QToolBar>#include<qgsmaptoolpan.h>#include <qgsmaptoolzoom.h>class qgis2 : public QMainWindow,private Ui::qgis2Class{Q_OBJECTpublic:qgis2(QWidget *parent = 0, Qt::WFlags flags = 0);~qgis2();public slots:void zoomInMode();void zoomOutMode();void panMode();void addLayer();private:Ui::qgis2Class ui;QgsMapCanvas *mpMapCanvas;QVBoxLayout *mpMapLayout;QToolBar * mpMapToolBar;QgsMapTool *mpPanTool;QgsMapTool *mpZoomInTool;QgsMapTool *mpZoomOutTool;};#endif // QGIS2_H

Step 4: Modify the qgis2.cpp File

# Include "qgis2.h" qgis2: qgis2 (qwidget * parent, QT: wflags flags): qmainwindow (parent, flags) {UI. setupui (this); qstring mypluginsdir = "C:/program files/qgis1.7.0/plugins"; qgsproviderregistry: instance (mypluginsdir ); // create a map canvas mpmapcanvas = new qgsmapcanvas (255,255,255); mpmapcanvas-> freeze (false); mpmapcanvas-> enableantialiasing (true); mpmapcanvas-> setcanvascolor (qcolor )); mpmapcanvas-> useimagetorender (False); mpmapcanvas-> setvisible (true); mpmapcanvas-> refresh (); mpmapcanvas-> show (); mpmapcanvas-> setfocus (); // layout the widget mpmaplayout = new qvboxlayout (); mpmaplayout-> addwidget (mpmapcanvas); UI. framemap-> setlayout (mpmaplayout); setcentralwidget (UI. framemap); // create action Action connect (UI. mpactionpan, signal (triggered (), this, slot (panmode (); Connect (UI. mpactionzoomin, signal (triggered (), this, slot (zoominmode (); Conn ECT (UI. mpactionzoomout, signal (triggered (), this, slot (zoomoutmode (); Connect (UI. mpactionaddlayer, signal (triggered (), this, slot (addlayer (); // create the toolbar function mpmaptoolbar = addtoolbar (TR ("file ")); mpmaptoolbar-> addaction (UI. mpactionaddlayer); mpmaptoolbar-> addaction (UI. mpactionpan); mpmaptoolbar-> addaction (UI. mpactionzoomin); mpmaptoolbar-> addaction (UI. mpactionzoomout); // create maptool function mppantool = new qgsmaptoolpan (M Pmapcanvas); mppantool-> setaction (UI. mpactionpan); mpzoomintool = new qgsmaptoolzoom (mpmapcanvas, false); mpzoomintool-> setaction (UI. mpactionzoomin); mpzoomouttool = new qgsmaptoolzoom (mpmapcanvas, true); mpzoomouttool-> setaction (UI. mpactionzoomout);} qgis2 ::~ Qgis2 () {Delete partition; Delete mpzoomintool; Delete mppantool; Delete mpmaptoolbar; Delete mpmapcanvas; Delete mpmaplayout;} void qgis2: panmode () {mpmapcanvas-> setmaptool (mppantool );} void qgis2: zoominmode () {mpmapcanvas-> setmaptool (mpzoomintool);} void qgis2: zoomoutmode () {mpmapcanvas-> setmaptool (volume);} void qgis2 :: addlayer () {// read Vector Data qstring mylayerpath = "e :\\ qgis \ project \ qgis2 \ data "; // change the Vector file qstring mylayerbasename = "test"; qstring mypovidername = "OGR"; qlist <qgsmapcanvaslayer> mylayerset; optional * mylayer = new struct (mylayerpath, mylayerbasename, mypovidername); If (mylayer-> isvalid () {qgssinglesymbolrenderer * myrenderer = new ender( mylayer-> geometrytype (); mylayer-> setrenderer (myrenderer ); // Add vector data to the layer to register qgsmaplayerregistry: instance ()-> addmaplayer (mylayer, true ); // set extentmpmapcanvas-> setextent (mylayer-> extent () of the canvas; // set the layer dataset mylayerset of the canvas. append (qgsmapcanvaslayer (mylayer); mpmapcanvas-> setlayerset (mylayerset);} else {return ;}}

Step 5: Modify the main. cpp File

#include "qgis2.h"#include <QtGui/QApplication>int main(int argc, char *argv[]){QgsApplication a(argc, argv,TRUE);qgis2 w;w.show();return a.exec();}

Step 6: The running result is as follows: