Allow downloading OpenRailwaysMap without background

pygmtsar/pygmtsar/XYZTiles.py

@@ -42,8 +42,18 @@ def download_openstreetmap(self, geometry, zoom, filename=None, **kwargs):
         kwargs['url'] = 'https://tile.openstreetmap.org/{z}/{x}/{y}.png'
         return self.download(geometry, zoom, filename, **kwargs)
 
-    def download_openrailwaymap(self, geometry, zoom, filename=None, **kwargs):
-        kwargs['url'] = 'https://mt1.google.com/vt/lyrs=r&x={x}&y={y}&z={z}'
+    def download_openrailwaymap(self, geometry, zoom, filename=None, background='Mapnik', **kwargs):
+        import xarray as xr
+        if background is None:
+            # [abc]
+            kwargs['url'] = 'https://a.tiles.openrailwaymap.org/standard/{z}/{x}/{y}.png'
+            tiles = self.download(geometry, zoom, filename, **kwargs)
+            tiles = xr.concat([tiles, 255*(tiles.sum('band') != 0)], dim='band')
+            return tiles
+        elif background == 'Mapnik':
+            kwargs['url'] = 'https://tile.openstreetmap.org/{z}/{x}/{y}.png'
+        else:
+            raise ValueError('Expected background "Mapnik" or None')
         return self.download(geometry, zoom, filename, **kwargs)
 
     def download(self, geometry, zoom, filename=None, url='https://mt1.google.com/vt/lyrs=y&x={x}&y={y}&z={z}', n_jobs=8, skip_exist=True, debug=False):