[Qgis-developer] Ellipse renderer

[Marco Hugentobler]

> (though there must be some magic to
> add the branch to a cloned main repository).

Ok, it works like this:

git remote add mhugent git://github.com/mhugent/Quantum-GIS.git
git fetch mhugent
git checkout --track mhugent/data_defined_symbollayer


> Am Dienstag, 14. Juni 2011, 17.50:12 schrieb Marco Hugentobler:
> Sorry, my git description does not work. It works with cloning my
> repository and checking out the branch (though there must be some magic to
> add the branch to a cloned main repository).
> 
> git clone git://github.com/mhugent/Quantum-GIS.git
> cd Quantum-GIS
> git checkout --track origin/data_defined_symbollayer
> 
> Marco
> 
> Am Dienstag, 14. Juni 2011, 15.48:29 schrieb Marco Hugentobler:
> > Hi QGIS devs
> > 
> > Recently, I was writing a symbollayer to render ellipse shapes (and also
> > rectangles, triangles, crosses by specifying width and height). Moreover,
> > the symbol layer allows to set all parameters (width, height, colors,
> > rotation, outline with) from data fields, in mm or map units.
> > 
> > The code is contained in my github clone int the branch
> > 'data_defined_symbollayer'. To give it a try, you can do the following:
> > 
> > git add remote add mhugent git://github.com/mhugent/Quantum-GIS.git
> > git checkout --track mhugent/data_defined_symbollayer
> > 
> > The reason it's in a branch is that data defined rendering in symbol
> > layers needed some API changes. They are quite small:
> > 
> > - A pointer to the rendered QgsFeature* has been added to
> > QgsSymbolV2RenderContext (such that the symbollayer has the possibility
> > to check the data defined attribute values)
> > 
> > - A symbollayer has the possibility to specify which attribute fields it
> > needs for rendering (by default, QgsSymbolLayerV2::usedAttributes returns
> > an empty set).
> > 
> > - The symbollayer widgets receive a pointer to their vector layer. Normal
> > symbol layer widgets don't use it, the widgets of  data defined symbol
> > layers get the available fields through that pointer.
> > 
> > At first, I tried to achieve the data defined layer without API change by
> > creating a new subclass of  QgsFeatureRendererV2 (as discussed with
> > Martin in Lisbon. However, it turned out this approach would need a lot
> > of duplication to provide graduated / unique / rule based classification
> > and to provide a seamless  integration with the existing symbology(ng).
> > 
> > What do you think?
> > 
> > Regards,
> > Marco


-- 
Dr. Marco Hugentobler
Sourcepole -  Linux & Open Source Solutions
Churerstrasse 22, CH-8808 Pfäffikon SZ, Switzerland
marco.hugentobler at sourcepole.ch http://www.sourcepole.ch
Technical Advisor QGIS Project Steering Committee