Adding a new Format

UDig makes use of a Catalog API that provides handles to all running services. You basically follow the handle to get access to the real data (be it DataStore, GridCoverage, or something new that you just made up).

These handles are called IService (which contains IGeoResource handles). Each has an associated "Info" object that captures the exact same information everyone always wants (name,title,icon,etc...)

Sometimes for a given "data" more then one handle is available (the data may be available through PostGIS and through a WMS). There is a voting system where the "best" renderer is chosen to render a layer. Some renderers can draw more then one layer (like WMS), some renderers like Shapefile renderer are stupidly fast.

Adding a new format to uDig involves introducing a catalog service and a renderer for your content type.

Catalog service

The catalog service is contributed via the net.refractions.udig.catalog.ServiceExtension extension point. This boils down to writing implementations of the following interfaces.

IService
IGeoResource
ServiceExtension

Renderer

The renderer is contributed via the net.refractions.udig.project.renderer extension point. This involves writing implementations of the following interfaces

IRenderer
IRenderMetrics
IRenderMetricsFactory

Plugin.xml

<extension
      point="net.refractions.udig.catalog.ui.fileFormat">
      <fileService fileExtension="*.mif"/>
      <fileService fileExtension="*.dxf"/>
   </extension>

MapInfo Data Interchange Format MIF
Autocad DXF Format