WMS decorations provide a framework for visually annotating images from WMS with absolute (rather than spatial) positioning. Examples of decorations include compasses, scalebars, and watermarks.
The WMS Decoration module is one that has gathered some interest and would be useful for generating single-file, annotated maps. One use-case (the one that motivated the implementation of this module in the first place) is as a 'Save current view' button for a web mapping application which includes such annotations.
The WMS Decoration feature is described at the WMS Decorations wiki page. There are some known issues:
* Requesting a decorated wms image causes geoserver to ignore the global watermark setting
* The legend decoration as implemented has no support for the (excellent) raster legends that geoserver now generates.
* Metatiling is broken in decorated wms output.
Obviously, these will be fixed before including the layout code in a GeoServer release.
Codewise, the following changes will be made:
* Move the Decoration, DecorationLayout, and decoration implementation classes into the core WMS module.
* Merge the modifications made in DecoratedRasterMapProducer to DefaultRasterMapProducer
To users, the feature will be available via a format_option on GeoServer raster output.
The layout id from the format options will have a 1:1 correlation with XML files in the configuration directory, in layouts/<id>.xml. If a user wants to disable layout support, he needs only clear out this directory (or rename it, if he wants to keep the layouts around for future use.) See the wiki page for details.
This section should contain feedback provided by PSC members who may have a problem with the proposal.
WMS decorations must be activated by a format option, so clients that are unaware of decorations will not be affected by them.