To see this, look at https://test.wikipedia.org/wiki/Mapframe#GeoShapes_external_data - Note how the Interstate Highway I-696 example does not specify a zoom/lat/lon, and autopositioning is not working in snapshot service. The Alaska example looks good because zoom/lat/lon are specified.
for example:
<mapframe lat=. lon=. zoom=.> { .ExternalData - WDQS query. } </mapframe>
if the lat/lon is missing, the map breaks.
Seems like some users have tried to make it without the lat/lon, so it would appear to be a needed feature. Raising to high. @JGirault - would you like to hack on it, or should I?
This feature is absolutely necessary! When people have to search manually for a suitable coordinate the whole advantage of <mapframe> is lost.
Hey @Yurik, I have a pull request. Do you mind reviewing https://github.com/kartotherian/kartotherian-snapshot/pull/2 ?
Generating an image may be a little slower with this feature because we have to download the external data before painting the base map.
Also after a first intent at reinventing the wheel without leaflet, I finally decided to reuse leaflet code to calculate the bounds.
The problem with this approach is that we have to fake a DOM, that's why I use leaflet-headless. Take a look and let me know what you think.
Update: the pull request was merged into kartotherian-snapshot master branch, now we need to deploy it to production.