create world files

[ruester]

When caching to disk or tiff it is useful to also create world files for the images.
So we are able to generate all tiles using mapcache_seed and then use the same raster data for a WMS service.

To use this feature following has to be added to the configuration file:

<cache ...>
    <create_world_file/>
</cache>

We used the file extension ".wld" for the world files as suggested by MapServer (see here).

[tbonfort]

could we remove this function, and instead factor in a forced extension in _mapcache_cache_disk_template_tile_key ?

[ruester]

something like:

static void _mapcache_cache_disk_tilecache_tile_key(mapcache_context *ctx, mapcache_tile *tile, char **path, char *extension)

and if extension == NULL we use the current behaviour of the function?
Otherwise we set the extension to "wld" ?

[tbonfort]

yes, exactly

[ruester]

That would be a bigger change...

All generic functions

lib/cache_disk.c:833:    dcache->tile_key = _mapcache_cache_disk_tilecache_tile_key;
lib/cache_disk.c:835:    dcache->tile_key = _mapcache_cache_disk_arcgis_tile_key;
lib/cache_disk.c:837:    dcache->tile_key = _mapcache_cache_disk_template_tile_key;

have to get this parameter, although they maybe never will use it.

As well as the interface in mapcache.h has to be changed:

struct mapcache_cache_disk {
  ...
  void (*tile_key)(mapcache_context *ctx, mapcache_tile *tile, char **path);
};

As an alternative we could implement a function to change the extension of a filename and use the current version of _mapcache_cache_disk_tilecache_tile_key.
But this could be as dirty as the internal API change...

[tbonfort]

both options are OK for me, as long as we're not duplicating the code just to use another extension

[ruester]

OK, I'll have a look at it...

[jbo-ads]

@ruester - Is this pull request still relevant?

[ruester]

As this PR is very old and was not merged till now, we can close it... If someone needs this feature they can use these commits to implement it for a newer version of mapcache 👍

[jmckenna]

@ruester we're doing a push for the upcoming 1.12.0 release and these changes could be included. Please re-open this as it is a good enhancement for the community.

[ruester]

Oh ok, sure you can add this, but I will have no time for rebasing the commits or fix the implementation if needed..

[jmckenna]

ok thanks for explaining. Closing.