GeoExtPrintForm - smarter resolution management for MapServer WMS layers

[adube]

Issue

When printing in a resolution greater than 72 dpi, the document produced by the MapFishPrint module is different than what we see on the web map application.

WMS

The WMS standard will include dpi management in 1.4, which is not available yet so managing this using WMS standards is currently not possible.

MapServer

In MapServer, setting the map "RESOLUTION" setting solves the issue as described here : ​http://mapserver.org/development/rfc/ms-rfc-55.html

Solution

So, for WMS MapServer services only (for now), we could use that parameter as a custom one in the print request. We would need a "mapserver" boolean option for the service for that. Since that's a feature we would always want, it would be automatically on when that service option is set.

[adube]

Fixed in r1150, featuring :

• a new 'vendor' service option for wms services. When set to 'mapserver', WMS layers are automatically created with this property set
• then, the GeoExtPrintForm widget now listen to the PrintProvicer "encodelayer" event and checks that 'vendor' property. If set to 'mapserver', then the "map_resolution" custom param is added in order to have the MapFishPrint module generate the according tiles in the right resolution.

This feature is only available for MapServer (for now) and version 5.6 or higher.

[adube]

Typo fix in r1151.