[udig-devel] rendering, styles, attributes

[Vince Darley <vince.darley@xxxxxxxxxxxx>]

Now that uDig's performance looks pretty good for our purposes, I'd like to 
ask a few questions which I haven't been able to answer from reading the 
documentation.

Render style by attribute value: The shapefiles I'm using (e.g. that large 
one with lots of points) have various attributes associated with each 
points.  I'd like to colour the points according to certain attribute 
values (e.g. vehicle_id).  How would I go about doing that in uDig (or can 
you point me to an outline of how I might achieve this with further 
development)?  I can see two paths to achieving this -- first just to have 
the ability to specify a render colour by attribute value, or second to 
split a layer by a given attribute, and then colour each newly-created 
layer manually.

1-2 years ago we did a fair amount of work on the j2drenderer from 
geotools, to add a more performant selection/modification capability (no 
need to re-render everything just because a few features have changed 
colour/appearance).  In the medium term we would probably want to use this, 
so I'm wondering what the path might be to have uDig use the j2d renderer 
(or something similar to that)?  Are the recent "point" performance 
improvements to the shapefile renderer somehow intertwined with the 
lite-renderer being used by uDig, or are they elsewhere in the rendering 
pipeline?  (Note: we'd probably be using a mixture of shapefiles and GML 
data for rendering purposes)

Another question of slightly lesser importance: is uDig's rendering 
pipeline at all suited to the idea of adding a dynamic, animated layer 
(e.g. vehicles moving around a street network, or ships across a river/sea 
network) under some circumstances?

cheers,

Vince.