QGIS二次开发第二讲

第一步：新建Qt Application 项目，名称为：qgis2，完成后，其解决方案的文件如下所示

第二步，设计UI

（1）双击，qgis2.ui文件，弹出qtDesigner设计器，添加相应菜单（对应的Action命名）如下图所示

（2）在面板中央的centralWidget中拖入一个QFrame容器（用来包含qgsmapcanvas），命名为frameMap；

（3）在qtDesigner中，点击保存，退出。

（4）在项目解决方案中，有点点击qgis2.ui，点击编译，使其重新生成ui_qgis2.h这个文件

第三步：修改qgis2.h文件

（PS:在Generated Files中有个ui_qgis2.h文件，此文件是有qgis2.ui文件自动生成的，无需修改，如需用到此类，用法当如：Ui::qgis2Class，如下代码所示）

修改的qigs2.h文件如下：

#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_OBJECT

public:
	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

第四步：修改qgis2.cpp文件

#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);
	//创建地图画布
	mpMapCanvas= new QgsMapCanvas(0,0);
	mpMapCanvas->freeze(false);
	mpMapCanvas->enableAntiAliasing(true);
	mpMapCanvas->setCanvasColor(QColor(255,255,255));
	mpMapCanvas->useImageToRender(false);
	mpMapCanvas->setVisible(true);
	mpMapCanvas->refresh();
	mpMapCanvas->show();
	mpMapCanvas->setFocus();
	
	
	//将窗口部件布局
	mpMapLayout = new QVBoxLayout();
	mpMapLayout->addWidget(mpMapCanvas);
	ui.frameMap->setLayout(mpMapLayout);
	setCentralWidget(ui.frameMap);

	//创建Action行为
	connect(ui.mpActionPan,SIGNAL(triggered()),this,SLOT(panMode()));
	connect(ui.mpActionZoomIn,SIGNAL(triggered()),this,SLOT(zoomInMode()));
	connect(ui.mpActionZoomOut,SIGNAL(triggered()),this,SLOT(zoomOutMode()));
	connect(ui.mpActionAddLayer,SIGNAL(triggered()),this,SLOT(addLayer()));

	//创建工具条功能
	mpMapToolBar=addToolBar(tr("File"));
	
	mpMapToolBar->addAction(ui.mpActionAddLayer);
	mpMapToolBar->addAction(ui.mpActionPan);
	mpMapToolBar->addAction(ui.mpActionZoomIn);
	mpMapToolBar->addAction(ui.mpActionZoomOut);
	//创建maptool功能
	mpPanTool= new QgsMapToolPan(mpMapCanvas);
	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 mpZoomOutTool;
	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(mpZoomOutTool);
}
void qgis2::addLayer()
{
	//读取矢量数据
	QString myLayerPath ="E:\\Qgis\\project\\qgis2\\data";// 此处换成自己的矢量文件
	QString myLayerBaseName = "test";
	QString myPoviderName="ogr";
	QList<QgsMapCanvasLayer> myLayerSet;
	QgsVectorLayer* myLayer = new QgsVectorLayer(myLayerPath,myLayerBaseName,myPoviderName);
	if (myLayer->isValid())
	{

	QgsSingleSymbolRenderer *myRenderer = new QgsSingleSymbolRenderer(myLayer->geometryType());
	myLayer->setRenderer(myRenderer);
	//增加矢量数据到图层注册
	QgsMapLayerRegistry::instance()->addMapLayer(myLayer,true);
	//设置画布的extent
	mpMapCanvas->setExtent(myLayer->extent());
	//设置画布的图层数据集
	myLayerSet.append(QgsMapCanvasLayer(myLayer));
	mpMapCanvas->setLayerSet(myLayerSet);
	}
	else
	{
		return;
	}
}

第五步：修改main.cpp文件

#include "qgis2.h"
#include <QtGui/QApplication>

int main(int argc, char *argv[])
{
	QgsApplication a(argc, argv,TRUE);
	qgis2 w;
	w.show();
	return a.exec();
}

第六步：运行结果如下：