[Qgis-developer] New angular renderer

[Michaël Douchin]

Hi !
I think this renderer goes in a good direction
I am personaly trying to find a way to draw arrows for each of my point 
, with the angle corresponding of the wind direction. I think this 
fonctionnality should not be used as a "unique value", "continuous 
renderere", etc. symbol type, but separatly, as it is done for the 
labels : we must be able for example to draw the points with
* a colour depending of one column (eg "boat speed" from green to red),
* a label representing another column (eg "name of the boat"),
* and another symbol like arrows (or anything else) drawn from the point 
with its angle contained in another column (eg "wind direction"). The 
best would be to have the possibility of changing the length of the 
arrow with another column (eg "wind speed").

What do you think ?

Michael

Magnus Homann a écrit :
> 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
>
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