[Qgis-developer] How do I change the symbol and its size from a provider?

Tim Sutton tim at linfiniti.com
Wed Jan 23 11:57:08 EST 2008

Hi Ken

I'm not sure that it makes sense to set symbology in your provider
itself so Im hoping you are trying to do it from some kind of add
layer gui, but you havent provided much information for me to know
whats really going on. That said here is how you can set the symbol on
a new vector layer instance programmatically:

 1572           QgsSymbol *  mypSymbol = new
 1573           QColor
 1574           mypSymbol->setFillColor(myPresenceColor);
 1575           mypSymbol->setColor(Qt::black); //outline
 1576           mypSymbol->setPointSize(mySymbolSize);
 1577           mypSymbol->setFillStyle(Qt::SolidPattern);
 1578           QgsSingleSymbolRenderer *mypRenderer = new
 1579           mypRenderer->addSymbol(mypSymbol);
 1580           mypVectorLayer->setRenderer(mypRenderer);

The above is a single symbol renderer take from one of my cpp
projects. The same project also implements a unigue value renderer -
see the original source at http://tinyurl.com/3xystm for more info.

I hope that helped!



2008/1/23, Ken Roser <kroser at roser.us>:
> I'm writing a plugin/provider that's similar in functionality to the
> delimited text plug in.  Things are working well, but I need to change
> the size, color and possibly the symbol itself when I add a point to the
> map.  I've been unable to determine a method of doing so other than
> going to the symbology tab on the layer properties dialog.  I want the
> change to happen automatically via the provider code.  Can anyone help out?
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Tim Sutton
QGIS Project Steering Committee Member - Release  Manager
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