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[udig-devel] How to get started with Renderer
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The following IRC chat is good ... and points to a need to improve our
documentation.
For background please read this document:
- http://portal.opengeospatial.org/files/?artifact_id=12911
While we have made some of the pictures available in our uDig wiki -
this document contains a clear summary *why* uDig rendering is set up
the way it is (ie what problem we are trying to solve).
jonathanv: my god
jonathanv: the udig drawing code sure is clever
***jgarnett:* you like the dynamic part? it is pretty sweet
*jgarnett:* The best way I have explained it is in an OGC document
*jgarnett:* I cut and pasted the pictures onto our wiki
*jgarnett:* but the most clear text is on the ogc document
jonathanv: i've been tracing for days and i still can't find the part
where it actually pulls data from a layer to draw it.
jonathanv: i wonder if this is why udig has so many rendering bugs.
*jgarnett:* um ... the things BasicFeatureRenderer
*jgarnett:* put together a GeoTolls MapContext
*jgarnett:* and use that to draw on a raster
*jgarnett:* the uDig code is all about just choosing the right
renderer for the data and style at hand.
*jgarnett:* if you look at the ossim plugin
*jgarnett:* you can see that it has a renderer that uses raw C++ code
*jgarnett:* and so on ...
*jgarnett:* when faced with several ways to get the same information
... say a WFS and a WMS with the same information
*jgarnett:* udig will choose what to use based on the style you have
set up
*jgarnett:* So either a BasicFeatureRenderer for the WFS
*jgarnett:* or a WMSRenderer to issue the WMS request
*jgarnett:* does this help?
jonathanv: i've found BasicFeatureRenderer
jonathanv: i'm going to do some tracing now and see if i can figure
out how this fits in
*jgarnett:* document is 05-116
*jgarnett:* http://portal.opengeospatial.org/files/?artifact_id=12911
*jgarnett:* That is the document!
*jgarnett:* but tracing through will work fine as well
*jgarnett:* please note that shapefiles are treated special - they
have a whole seperate renderer that is optimized just for them.
*jgarnett:* So if you trace through with a shapefile things will look
way more scary then usual.
