[udig-devel] Default style on custom file type

["Wellmann, Harald" <HWellmann@xxxxxxxxxxxxxxxx>]

I'm trying to write a uDIG plug-in that renders a custom file type *.foo and applies a default drawing style whenever a user opens a file with extension .foo.

The .foo files contain all sorts of feature types to be rendered in different styles. The user shall _not_ be burdened with editing an SLD file, I just want him to open a file and see water features in blue, parks in green, roads in grey etc.

I created an extension fooStyle for net.refractions.udig.project.style that implements the StyleContent interface. My method createDefaultStyle() checks if the IGeoResource is a FooGeoResource, and if so, it reads an SLD file as a resource relative to the current class and builds a Style object from it which will then be placed onto the StyleBlackboard by the caller.

Now the problem is how to ensure that the BasicFeatureRenderer selects my fooStyle instead of the standard sldStyle.

As far as I can see, the renderer simply takes the first Style object from the blackboard, and I can't figure out how to make sure that my fooStyle appears _before_ the sldStyle. It seems the order on the blackboard depends on the order of the extensions for the style extension point, which in turn depends on the OSGi bundle order of the corresponding plug-ins, and I don't see how I can influence the bundle sequence number.

In fact, I installed my plug-in in several different Eclipse instances, and my  plug-in appears sometimes first and sometimes last in the list.

OSGi tells you not to rely on a given bundle activation order, as bundles may come and go at any time.

If my bundle gets activated first, everything is fine, since my style is the first on the blackboard. If my bundle gets activated last, I'm not sure what to do. As a workaround, I currently set my bundle id to net.refractions.udig.style.sld (only in the implementation class, not in the plugin.xml) so that my style overwrites the sldStyle on the blackboard.

Is there a more intelligent way of disabling the default style? Is there a way of defining a filetype-to-style mapping?

Best regards,

Harald 
 
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