Merge pull request #1037 from davidbrochart/as_leaflet_layer

Fix as_leaflet_layer

Author: davidbrochart

ipyleaflet/leaflet.py

@@ -1172,8 +1172,6 @@ def add(self, layer):
 
         if isinstance(layer, dict):
             layer = basemap_to_tiles(layer)
-        elif hasattr(layer, 'as_leaflet_layer'):
-            layer = layer.as_leaflet_layer()
         if layer.model_id in self._layer_ids:
             raise LayerException('layer already in layergroup: %r' % layer)
         self.layers = tuple([layer for layer in self.layers] + [layer])
@@ -2525,6 +2523,9 @@ def add(self, item):
         item: Layer or Control instance
             The layer or control to add.
         """
+        if hasattr(item, 'as_leaflet_layer'):
+            item = item.as_leaflet_layer()
+
         if isinstance(item, Layer):
             if isinstance(item, dict):
                 item = basemap_to_tiles(item)