I lean towards not doing this, since we'd need to keep libchamplain updated with regards to new versions of mapbox's tilesets.

Just do something like this instead: 
https://git.gnome.org/browse/gnome-maps/tree/src/mapSource.js#n45

In the end it's up to Jiri though. :)

I'd probably prefer having only map sources in libchamplain that work without any additional configuration (at the moment we don't have any mechanism to add e.g. the access token parameter to a factory tile source).

However, it's really easy to create a custom tile source - I've just added a new sample to libchamplain demonstrating this. It uses the same caching which is used for the factory sources and everything should work the same way as if it was part of libchamplain. You can find it here:

https://git.gnome.org/browse/libchamplain/tree/demos/mapbox.py

You only need to provide the ACCESS_TOKEN value and everything should work.

If you want to do the same in C, this:

https://git.gnome.org/browse/libchamplain/tree/champlain/champlain-map-source-factory.c#n456

might help you. Let me know if you need some help.

(Jiri Techet)
 
Here is what I ended up doing with mapbox, and it seems to be working fine.
(I don't fully understand this API - just enough to get it working).

Thanks for your help. The application is fotoxx in case you want to know.
 
One problem remains: place names are in the local language (e.g. Chinese characters)
(the same issue I had with mapnik). Do you have an easy fix?
If not, I will spend more time on the mapbox developer pages to see if this can be customized.
Gnome maps does not have this problem. Also using mapbox?


//-------------------------------------------------------------------------------

   #define LICENSE_TEXT ""
   #define LICENSE_URI "https://www.mapbox.com/tos/"
   #define ACCESS_TOKEN "pk.***************"
   #define URI "https://a.tiles.mapbox.com/v4/mapbox.streets/#Z#/#X#/#Y#.png?access_token=" ACCESS_TOKEN
   #define FILE_CACHE 200000000     /* MB */
   #define MEMORY_CACHE 200         /* tiles */

   ChamplainMapSourceFactory   *map_factory;
   ChamplainRenderer           *renderer;
   ChamplainMapSource          *error_source;
   ChamplainNetworkTileSource  *tile_source;
   ChamplainFileCache          *file_cache;
   ChamplainMemoryCache        *memory_cache;
   ChamplainMapSourceChain     *source_chain;

   renderer = CHAMPLAIN_RENDERER(champlain_image_renderer_new());

   map_factory = champlain_map_source_factory_dup_default();
   
   tile_source = champlain_network_tile_source_new_full (
         "mapbox", "mapbox", LICENSE_TEXT, LICENSE_URI, 0, 19, 256,
         CHAMPLAIN_MAP_PROJECTION_MERCATOR, URI, renderer);
   
   error_source = champlain_map_source_factory_create_error_source(map_factory,256);
   file_cache = champlain_file_cache_new_full(FILE_CACHE, null, renderer);
   memory_cache = champlain_memory_cache_new_full(MEMORY_CACHE, renderer);

   source_chain = champlain_map_source_chain_new();
   champlain_map_source_chain_push(source_chain, error_source);
   champlain_map_source_chain_push(source_chain, CHAMPLAIN_MAP_SOURCE(tile_source));
   champlain_map_source_chain_push(source_chain, CHAMPLAIN_MAP_SOURCE(file_cache));
   champlain_map_source_chain_push(source_chain, CHAMPLAIN_MAP_SOURCE(memory_cache));
   
   champlain_view_set_map_source(mapview, CHAMPLAIN_MAP_SOURCE(source_chain));

//-------------------------------------------------------------------------------

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