1.加载在线的高德地图
以下是在线高德地图地址。
http://webrd01.is.autonavi.com/appmaptile?x={x}&y={y}&z={z}&lang=zh_cn&size=1&scale=1&style=8以下是代码示例：
#include <QApplication>
#include <QMainWindow>
#include "qgisinterface.h"
#include "qgsproviderregistry.h"
#include "qgsrasterlayer.h"
#include "qgsproject.h"
#include "qgsmapcanvas.h"
int main(int argc, char *argv[])
{
// 初始化QGIS
QgsApplication app(argc, argv, true);
app.initQgis();
// 创建主窗口
QMainWindow mainWindow;
mainWindow.setWindowTitle("QGIS with Amap");
// 创建地图Canvas
QgsMapCanvas* mapCanvas = new QgsMapCanvas(&mainWindow);
mapCanvas->setCanvasColor(Qt::white);
mapCanvas->setVisible(true);
mapCanvas->setFrameStyle(0);
mainWindow.setCentralWidget(mapCanvas);
// 创建栅格图层
QgsRasterLayer* amapLayer = new QgsRasterLayer("http://webrd01.is.autonavi.com/appmaptile?x={x}&y={y}&z={z}&lang=zh_cn&size=1&scale=1&style=8", "Amap", "wms");
if (amapLayer->isValid())
{
QgsProject::instance()->addMapLayer(amapLayer);
QgsRectangle extent = amapLayer->extent();
mapCanvas->setExtent(extent);
}
else
{
QMessageBox::critical(&mainWindow, "Error", "Could not load Amap layer.");
return -1;
}
// 设置地图范围和投影
QgsCoordinateReferenceSystem crs("EPSG:3857");
mapCanvas->setDestinationCrs(crs);
mapCanvas->enableAntiAliasing(true);
// 显示主窗口
mainWindow.show();
// 执行QGIS事件循环
return app.exec();
}结果运行结果无效并报错：
Raster layer Cannot instantiate the 'wms' data provider
大概的意思就是说不能初始化wms的东西，就是wms的相关驱动没有加载好。
解决办法：
1.设置路径
//设置前缀路径
QgsApplication app(argc, argv, true);
app.setPrefixPath("E:/OSGeo4W/apps/qgis-ltr-dev", true);
app.initQgis();2.将驱动文件拷贝到运行目录下
不需要设置setPrefixPath()。
将E:/OSGeo4W/apps/qgis-ltr-dev/plugins目录拷贝到生成程序的运行目录下，因为程序启动起来加载的是本地的plugins下的插件。
注意不要拷贝错了，我下载的目录下有两个qgis目录，你使用的哪个路径下的库来编译的程序，就拷贝哪个路径下的plugins目录，否则有可能导致程序起不来。
2.如果url填入不能进行正常加载
提供一个编码url的类
#ifndef QGSXYZCONNECTION_H
#define QGSXYZCONNECTION_H
#include <QStringList>
struct QgsXyzConnection
{
QString name;
QString url;
int zMin = -1;
int zMax = -1;
// Authentication configuration id
QString authCfg;
// HTTP Basic username
QString username;
// HTTP Basic password
QString password;
// Referer
QString referer;
// tile pixel ratio (0 = unknown (not scaled), 1.0 = 256x256, 2.0 = 512x512)
double tilePixelRatio = 0;
bool hidden = false;
QString encodedUri() const;
};
//! Utility class for handling list of connections to XYZ tile layers
class QgsXyzConnectionUtils
{
public:
//! Returns list of existing connections, unless the hidden ones
static QStringList connectionList();
//! Returns last used connection
static QString selectedConnection();
//! Saves name of the last used connection
static void setSelectedConnection( const QString &connName );
//! Returns connection details
static QgsXyzConnection connection( const QString &name );
//! Removes a connection from the list
static void deleteConnection( const QString &name );
//! Adds a new connection to the list
static void addConnection( const QgsXyzConnection &conn );
};
#endif // QGSXYZCONNECTION_H
#include <qgslogger.h>
#include "qgsxyzconnection.h"
#include <qgsdatasourceuri.h>
#include <qgssettings.h>
QString QgsXyzConnection::encodedUri() const
{
QgsDataSourceUri uri;
uri.setParam( QStringLiteral( "type" ), QStringLiteral( "xyz" ) );
uri.setParam( QStringLiteral( "url" ), url );
if ( zMin != -1 )
uri.setParam( QStringLiteral( "zmin" ), QString::number( zMin ) );
if ( zMax != -1 )
uri.setParam( QStringLiteral( "zmax" ), QString::number( zMax ) );
if ( ! authCfg.isEmpty() )
uri.setAuthConfigId( authCfg );
if ( ! username.isEmpty() )
uri.setUsername( username );
if ( ! password.isEmpty() )
uri.setPassword( password );
if ( ! referer.isEmpty() )
uri.setParam( QStringLiteral( "referer" ), referer );
if ( tilePixelRatio != 0 )
uri.setParam( QStringLiteral( "tilePixelRatio" ), QString::number( tilePixelRatio ) );
return uri.encodedUri();
}
QStringList QgsXyzConnectionUtils::connectionList()
{
QgsSettings settings;
QStringList connList;
settings.beginGroup( QStringLiteral( "qgis/connections-xyz" ) );
connList = settings.childGroups();
const QStringList global = settings.globalChildGroups();
settings.endGroup();
for ( const auto &s : global )
{
settings.beginGroup( "qgis/connections-xyz/" + s );
bool isHidden = settings.value( QStringLiteral( "hidden" ), false ).toBool();
settings.endGroup();
if ( isHidden )
{
connList.removeOne( s );
}
}
return connList;
}
QString QgsXyzConnectionUtils::selectedConnection()
{
QgsSettings settings;
return settings.value( QStringLiteral( "qgis/connections-xyz/selected" ) ).toString();
}
void QgsXyzConnectionUtils::setSelectedConnection( const QString &name )
{
QgsSettings settings;
return settings.setValue( QStringLiteral( "qgis/connections-xyz/selected" ), name );
}
QgsXyzConnection QgsXyzConnectionUtils::connection( const QString &name )
{
QgsSettings settings;
settings.beginGroup( "qgis/connections-xyz/" + name );
QgsXyzConnection conn;
conn.name = name;
conn.url = settings.value( QStringLiteral( "url" ) ).toString();
conn.zMin = settings.value( QStringLiteral( "zmin" ), -1 ).toInt();
conn.zMax = settings.value( QStringLiteral( "zmax" ), -1 ).toInt();
conn.authCfg = settings.value( QStringLiteral( "authcfg" ) ).toString();
conn.username = settings.value( QStringLiteral( "username" ) ).toString();
conn.password = settings.value( QStringLiteral( "password" ) ).toString();
conn.referer = settings.value( QStringLiteral( "referer" ) ).toString();
conn.tilePixelRatio = settings.value( QStringLiteral( "tilePixelRatio" ), 0 ).toDouble();
conn.hidden = settings.value( QStringLiteral( "hidden" ) ).toBool();
return conn;
}
void QgsXyzConnectionUtils::deleteConnection( const QString &name )
{
QgsSettings settings;
settings.remove( "qgis/connections-xyz/" + name );
settings.beginGroup( QStringLiteral( "qgis/connections-xyz" ) );
QStringList global = settings.globalChildGroups();
if ( global.contains( name ) )
{
QgsSettings settings;
settings.beginGroup( "qgis/connections-xyz/" + name );
settings.setValue( QStringLiteral( "hidden" ), true );
}
}
void QgsXyzConnectionUtils::addConnection( const QgsXyzConnection &conn )
{
QgsSettings settings;
bool addHiddenProperty = false;
settings.beginGroup( QStringLiteral( "qgis/connections-xyz" ) );
QStringList global = settings.globalChildGroups();
if ( global.contains( conn.name ) )
{
addHiddenProperty = true;
}
settings.endGroup();
settings.beginGroup( "qgis/connections-xyz/" + conn.name );
settings.setValue( QStringLiteral( "url" ), conn.url );
settings.setValue( QStringLiteral( "zmin" ), conn.zMin );
settings.setValue( QStringLiteral( "zmax" ), conn.zMax );
settings.setValue( QStringLiteral( "authcfg" ), conn.authCfg );
settings.setValue( QStringLiteral( "username" ), conn.username );
settings.setValue( QStringLiteral( "password" ), conn.password );
settings.setValue( QStringLiteral( "referer" ), conn.referer );
settings.setValue( QStringLiteral( "tilePixelRatio" ), conn.tilePixelRatio );
if ( addHiddenProperty )
{
settings.setValue( QStringLiteral( "hidden" ), false );
}
}
使用：
QgsXyzConnection xyz;
xyz.url = QStringLiteral("http://webrd01.is.autonavi.com/appmaptile?x={x}&y={y}&z={z}&lang=zh_cn&size=1&scale=1&style=8");
xyz.zMin = 0;
xyz.zMax = 18;
xyz.tilePixelRatio = 1.0;
QgsXyzConnectionUtils::addConnection(xyz);
QString url2 = xyz.encodedUri();
qDebug() << "url2 = " << url2;
QgsRasterLayer *layer = addRasterLayerPrivate(url2, QStringLiteral("ocr0"), QStringLiteral("wms"));
