def render_single_tile(m: StaticMap, ext: list) -> Image:
"""
Revised version of StaticMap.render() allows explicit extent + empty maps
Args:
m: Static map object for rendering
ext: the map extent in (min_lon, min_lat, max_lon, max_lat)
Returns:
The returned RGB image as an PIL.Image
"""
ex_poly = [[ext[0], ext[1]],
[ext[0], ext[3]],
[ext[2], ext[1]],
[ext[2], ext[3]]]
polygon = Polygon(ex_poly, 'white', 'white', True)
m.add_polygon(polygon)
m.zoom = m._calculate_zoom()
# get extent of all lines
extent = ext
# calculate center point of map
lon_center, lat_center = (extent[0] + extent[2]) / 2, (extent[1] + extent[3]) / 2
m.x_center = _lon_to_x(lon_center, m.zoom)
m.y_center = _lat_to_y(lat_center, m.zoom)
image = Image.new('RGB', (m.width, m.height), m.background_color)
m._draw_base_layer(image)
m.polygons.remove(polygon)
m._draw_features(image)
return image
