I would like to change the coordinatereferencesystem for my application

I have this code :

QgsMapRenderer* myRender = mapRenderer();
mQgsCoordinate = new QgsCoordinateReferenceSystem(myRender->destinationCrs());
myRender->setMapUnits( QGis::Meters );
myRender->setProjectionsEnabled( true );
qDebug() << " mQgsCoordinate = " << mQgsCoordinate->description();
if( mQgsCoordinate->isValid())
    qDebug() << "CMyQgsMapCanvas::setProjection OK";
    qDebug() << "CMyQgsMapCanvas::setProjection NOK";

I have always NOK and the mQgsCoordinate->desciption which return a QString is always Empty !!! What's wrong ? Did I forget a step to change the CorodinateReferenceSystem ?

1 Answer 1


Make sure you get the identifier correct:


You get a return value directly from the createFromOgcWmsCrs method which indicates if the call was ok.

To make your development easier: it's straightforward to use the python console for finding the correct usage:

>>> a = QgsCoordinateReferenceSystem()
>>> a.createFromOgcWmsCrs('CRS83')
>>> a.createFromOgcWmsCrs('CRS:83')
  • Thanks, I have checked the syntax and it was correct, I have made a test with "OGC:CRS83" and i have the same problem. Finally after check the code i found the problem. The problem is when i make a setExtent of the mMapCanvas.
    – ainardi
    Jul 23, 2015 at 13:52

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