Handle serialization and deserialization of Colormap and lists of col…

…ors.

localtileserver/client.py

@@ -2,6 +2,7 @@
 import logging
 import pathlib
 from typing import List, Optional, Union
+from matplotlib.colors import Colormap
 
 import rasterio
 import requests
@@ -416,7 +417,7 @@ def create_url(self, path: str, client: bool = False):
     def get_tile_url(
         self,
         indexes: Optional[List[int]] = None,
-        colormap: Optional[str] = None,
+        colormap: Optional[Union[str, Colormap]] = None,
         vmin: Optional[Union[float, List[float]]] = None,
         vmax: Optional[Union[float, List[float]]] = None,
         nodata: Optional[Union[int, float]] = None,
@@ -441,13 +442,23 @@ def get_tile_url(
             The value from the band to use to interpret as not valid data.
 
         """
+        import json
         # First handle query parameters to check for errors
         params = {}
         if indexes is not None:
             params["indexes"] = indexes
         if colormap is not None:
-            # make sure palette is valid
-            palette_valid_or_raise(colormap)
+
+            if isinstance(colormap, Colormap):
+                colormap = json.dumps(
+                    {k:tuple(v.tolist()) for k,v in enumerate(colormap(range(256),1,1))}
+                )
+            elif isinstance(colormap, list):
+                colormap = json.dumps(colormap)
+            else:
+                # make sure palette is valid
+                palette_valid_or_raise(colormap)
+
             params["colormap"] = colormap
         if vmin is not None:
             if isinstance(vmin, Iterable) and not isinstance(indexes, Iterable):

localtileserver/tiler/handler.py

@@ -150,7 +150,21 @@ def _render_image(
     colormap: Optional[str] = None,
     img_format: str = "PNG",
 ):
-    colormap = cmap.get(colormap) if colormap else None
+    import json
+    from matplotlib.colors import LinearSegmentedColormap
+
+    if colormap in cmap.list():
+        colormap = cmap.get(colormap)
+    else:
+        c = json.loads(colormap)  
+        if isinstance(c, list):
+            c = LinearSegmentedColormap.from_list('', c, N=256)
+            colormap = {k:tuple(v) for k,v in enumerate(c(range(256),1,1))}
+        else:
+            colormap = {}
+            for key,value in c.items():
+                colormap[int(key)] = tuple(value)
+
     if (
         not colormap
         and len(indexes) == 1

localtileserver/widgets.py

@@ -1,6 +1,7 @@
 import logging
 import pathlib
 from typing import List, Optional, Union
+from matplotlib.colors import Colormap
 import warnings
 
 import rasterio
@@ -23,7 +24,7 @@ def get_leaflet_tile_layer(
     port: Union[int, str] = "default",
     debug: bool = False,
     indexes: Optional[List[int]] = None,
-    colormap: Optional[str] = None,
+    colormap: Optional[Union[str, Colormap]] = None,
     vmin: Optional[Union[float, List[float]]] = None,
     vmax: Optional[Union[float, List[float]]] = None,
     nodata: Optional[Union[int, float]] = None,