Support for WMS layer #2
Description
In addition to the existing support for Simple Style GeoJSON as well as Leaflet based Circle layers adding WMS based sources increases the available base maps to add to snapshots.
Proof of Concept
A working proof of concept for adding WMS support to the Snapshot specification can be found here. The current version of sandbox.gemeindescan.ch has experimental support for WMS layers.
An example can be seen here: https://sandbox.gemeindescan.ch/de/SLF3GE/
Technical detail
Web Map Services (WMS) publishe tiled pixel based maps. These can be added to Leaflet by default with L.tileLayer.wms.
In order to support WMS a MIME-Type of application/vnd.wms can be used as datapackage.resource.mediatype.
Issues / Limitations
The proof of concept has no easy way of integrating existing legends from a WMS layer automatically since it's legend format is not compatible with Snapshot legends. A workaround is manually adding the relevent entries in datapackage.view.spec.legend.