Do not draw transparent polygons

[lvonlanthen]

Do not draw polygons on the map if fill_color and outline_color are None.

m = StaticMap(500, 400)
m.add_marker(CircleMarker((7.15, 46.80), '#0036FF', 12))
bbox_coords = [
    [5.96, 47.81],
    [5.96, 45.83],
    [10.49, 45.83],
    [10.49, 47.81],
    [5.96, 47.81]]
m.add_polygon(Polygon(bbox_coords, None, None))
image = m.render()
image.save('map.png')

Creates a thin polygon even though fill_color = None and outline_color = None. See https://imgur.com/yr3nQSX

[christophlingg]

What's the point of drawing a invisble polygon? But it's still a misbehaviour of the lib, great fix!

[lvonlanthen]

I have a use case where I always want to zoom to the entire country of a marker. So basically, I want to have a fixed extent of the map. As there is no function such as StaticMap.set_extent(bbox), I am adding an invisible polygon (the bounding box of the country) so the extent calculated in StaticMap.determine_extent() shows the entire country. It is probably not the most elegant way, but it works, especially now that the bbox is not showing anymore. Thanks for accepting my change!

[christophlingg]

That's a use case I haven't thought of yet, but it's relevant. I will create a corresponding ticket.