I write a Standalone C++ Application and I can not load a vector layer. This is the error:
QObject::connect: Cannot connect (null)::raiseError( QString ) to QgsVectorLayer::raiseError( QString )
Now, this is my code for application:
#include "mainwindow.h"
#include <QApplication>
#include <QDebug>
#include "qgsapplication.h"
int main(int argc, char *argv[])
{
QString pluginPath = "/home/scit/dev/cpp/QGIS/build-master/plugins";
QString prefixPath = "/home/scit/dev/cpp/QGIS/build-master";
qDebug() << "Step 1";
QgsApplication::setPluginPath( pluginPath );
QgsApplication::setPrefixPath( prefixPath, true);
QgsApplication a(argc, argv, true);
a.initQgis();
qDebug() << a.showSettings();
MainWindow w;
w.show();
return a.exec();
}
Where "/home/scit/dev/cpp/QGIS/build-master/plugins" you can find all *.so libraries for plugin of a build of QGIS.
this->mapCanvas = new QgsMapCanvas(ui->centralWidget, "The_Canvas");
ui->gridLayout->addWidget( this->mapCanvas, 0, 0, 2, 1 );
....
QgsVectorLayer *layer = new QgsVectorLayer( "/home/scit/Descargas/ne_10m_populated_places.shp", base, "ogr", false );
Q_CHECK_PTR( layer );
if ( layer->isValid() ){
qDebug() << "VALID";
this->mapCanvas->setExtent(layer->extent());
QList<QgsMapLayer*> myList;
myList << layer;
QgsMapLayerRegistry::instance()->addMapLayers( myList );
this->mapCanvas->freeze(false);
this->mapCanvas->refresh();
}else{
qDebug() << "INVALID";
}
And my .pro for QT project
QT += core gui network sql xml
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
TARGET = qgisExtension
TEMPLATE = app
SOURCES += main.cpp\
mainwindow.cpp
HEADERS += mainwindow.h
FORMS += mainwindow.ui
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/ -lqgis_core
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/ -lqgis_analysis
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/ -lqgis_app
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/ -lqgis_gui
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/ -lqgispython
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/ -lqgis_networkanalysis
#I do not know if this is necessary!!!!!
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libbasicauthmethod.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libgeometrycheckerplugin.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libgrassprovider6.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libmssqlprovider.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libpkipathsauthmethod.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libspatialiteprovider.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libwmsprovider.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libcoordinatecaptureplugin.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libgeometrysnapperplugin.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libgrassrasterprovider6.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libofflineeditingplugin.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libpostgresprovider.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libspatialqueryplugin.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libzonalstatisticsplugin.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libdelimitedtextprovider.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libgeorefplugin.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libheatmapplugin.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libogrprovider.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libqgisgrass6.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libtopolplugin.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libdxf2shpconverterplugin.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libgpsimporterplugin.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libidentcertauthmethod.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/liboracleplugin.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libqgisgrass6.so.2.14.5
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libvirtuallayerprovider.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libevis.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libgpxprovider.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libinterpolationplugin.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libowsprovider.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/librasterterrainplugin.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libwcsprovider.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libgdalprovider.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libgrassplugin6.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libmemoryprovider.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libpkcs12authmethod.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libroadgraphplugin.so
LIBS += -L$$PWD/../../../cpp/QGIS/build-master/output/lib/qgis/plugins/libwfsprovider.so
INCLUDEPATH += $$PWD/../../../cpp/QGIS/src/core
DEPENDPATH += $$PWD/../../../cpp/QGIS/src/core
INCLUDEPATH += $$PWD/../../../cpp/QGIS/src/core/geometry
DEPENDPATH += $$PWD/../../../cpp/QGIS/src/core/geometry
INCLUDEPATH += $$PWD/../../../cpp/QGIS/src/gui
DEPENDPATH += $$PWD/../../../cpp/QGIS/src/gui
INCLUDEPATH += $$PWD/../../../cpp/QGIS
DEPENDPATH += $$PWD/../../../cpp/QGIS
QMAKE_CXXFLAGS += -std=c++0x
DEFINES += GUI_EXPORT= CORE_EXPORT=
