Explicit Map Extent

[christophlingg]

see #3

[maxvonhippel]

This is a feature I also need. I'm new to the static map library, but I'd be happy to work on adding this myself. Do you happen to know where in the code I should start?

[maxvonhippel]

Ok, just submitted a pull request to fix this. I did not add support for explicit map extent for maps which are not blank because that is a) not a feature I need (sorry for being selfish) and b) a much more difficult feature to implement, however, I did add support for explicit map extent for blank maps. This is a more useful feature than you might presume. For example, for my use case, I am creating .gif's of mapping over time from OSM data, and on some days there is no activity so I need to show a blank map. But I don't want to just center on [0.0], I want to stay looking at the place I was looking at before. For use cases such as that, the ability to explicitly define a blank map is useful. See more here.