[Qgis-developer] New angular renderer

Tim Sutton tim at linfiniti.com
Mon Dec 10 10:31:41 EST 2007


2007/12/10, Michaël Douchin <michael.douchin at laposte.net>:
> 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 ?

Yes that makes sense to me too - so basically make symbol rotation an option
on all renderertypes when they are rendering point symbols.

For dynamically colouring symbols my hope / plan was that we can

a) get rid of the 'fixed' symbols (currently the only ones that allow colouring)
b) implement SVG css and a convention for our svg files to that we can
dynamically colour them

Anybody looking for a bit of diversion? - the above would be a great



> 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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> > Qgis-developer at lists.qgis.org
> > http://lists.qgis.org/cgi-bin/mailman/listinfo/qgis-developer
> >
> >
> >
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Tim Sutton
QGIS Project Steering Committee Member - Release  Manager
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