Add support for GetLegendGraphic

[fredmorin]

Use the source url to execute getlegendgraphic. Forwarding rules are too restrictive to request getlegendgraphic when exposing multiple tileset/sources.

[fredmorin]

Untested implementation available at https://github.com/fredmorin/mapcache

[tbonfort]

Please explain why forwarding rules are too limited. What should the behavior be when multiple layers/tilesets are requested in a single getlegendgraphic request?

[fredmorin]

I have multiple wms sources, with different urls. I want to forward the GetLegendGraphic request to the source url. I have to create one forwarding rule for each source.

If mapcache could forward GetLegendGraphic requests to source service as it forwards GetFeatureInfo, we wouldn't have to write multiple forwarding rules.

[jbelien]

Is there any news on this topic ? :)