[Qgis-developer] New angular renderer

[Magnus Homann]

I got inspired be the eVis plugin (great!) and took the liberty of 
hacking a new renderer, called angular renderer.
With it, you can select a column that determines which angle the symbol 
should have:

Screenshot:
http://img264.imageshack.us/my.php?image=angularif2.png

It's very much like the single symbol renderer, only this extra field 
for determining which column keeps the direction angle.
In fact, my changes should maybe be incorporated into Single Symbol instead?

Looking at the rendering implementation, perhaps it would be good to
make a renderer interface similar to plugin/provider, so that qgis finds
a catalog of renderers? Is this perhasp the same thing that is being 
done in diagram-branch? Don't know much about that, though.

I can see a couple of options
a) Change Single Symbol to include angle.
b) Add another hard-coded renderer for angular symbol (as shown in 
screenshot)
c) Make the interface for renderers a bit more general, but still 
require them to be compiled with Qgis. A new renderer requires just two 
more files.
d) Create a new render DLL interface.
e) Make renderer and diagram overlay the same stuff (no idea if this is 
possible).

The order is how I prefer to do it. a) -c) I can manage myself, but 
d)-e) requires knowledge and stamina I might not possess. :-)

Magnus Homann