`contextily` compatible to `basemap`?

[a-ma72]

I try to add a map to coastlines drawn with basemap, (both sources use the the same WGS84 Web Mercator projection):

import contextily as cx
import matplotlib.pyplot as plt
from mpl_toolkits.basemap import Basemap


# Map source
source = cx.providers.OpenStreetMap.Mapnik

# Plot
fig, ax = plt.subplots(figsize=(10, 10))

m = Basemap(
    projection="merc",  # Mercator-Projektion
    epsg=3857,          # WGS84 Web Mercator
    llcrnrlat=44.82,
    urcrnrlat=55.30,
    llcrnrlon=5.89,
    urcrnrlon=15.56,
    resolution="i",
    ax=ax,
)
m.drawcoastlines()

# Add context-basemap
cx.add_basemap(ax, crs="EPSG:3857", source=source)

# Show
plt.show()

but the maps doesn't match:

Is contextily compatible to basemap at all?

[martinfleis]

contextily assumes that coordinates used in the Matplotlib object match the coordinates expected by the set CRS. I believe that Basemap is transforming those in some way that makes it different. For example, in the case of the code above:

box = ax.get_window_extent()
box.corners()

array([[285.66987562, 110.        ],
       [285.66987562, 880.        ],
       [739.33012438, 110.        ],
       [739.33012438, 880.        ]])

While contextily expects something like

geopandas.GeoSeries([shapely.box(5.89, 44.82, 15.56, 55.30)], crs=4326).to_crs(3857).total_bounds

array([ 655671.80077238, 5593228.54285185, 1732131.27674334,
       7420309.04808307])