Merge pull request #1066 from jakevdp/sphinx-no-selenium

MAINT: make doc build work without selenium

altair/sphinxext/altairgallery.py

@@ -4,6 +4,7 @@
 import random
 import collections
 from operator import itemgetter
+import warnings
 
 import jinja2
 
@@ -14,7 +15,8 @@
 
 from sphinx.util.nodes import nested_parse_with_titles
 
-from .utils import get_docstring_and_rest, prev_this_next, create_thumbnail
+from .utils import (get_docstring_and_rest, prev_this_next,
+                    create_thumbnail, create_generic_image)
 from altair.utils.execeval import eval_block
 from altair.vegalite.v2.examples import iter_examples
 
@@ -126,8 +128,12 @@ def save_example_pngs(examples, image_dir, make_thumbnails=True):
             # the file changed or the image file does not exist. Generate it.
             print('-> saving {0}'.format(image_file))
             chart = eval_block(example['code'])
-            chart.save(image_file)
-            hashes[filename] = example_hash
+            try:
+                chart.save(image_file)
+                hashes[filename] = example_hash
+            except ImportError:
+                warnings.warn("Could not import selenium: using generic image")
+                create_generic_image(image_file)
 
             with open(hash_file, 'w') as f:
                 json.dump(hashes, f)

altair/sphinxext/utils.py

@@ -28,6 +28,21 @@ def create_thumbnail(image_filename, thumb_filename, window_size=(144, 80)):
     thumb.save(thumb_filename)
 
 
+def create_generic_image(filename, shape=(200, 300), gradient=True):
+    """Create a generic image"""
+    from PIL import Image
+    import numpy as np
+
+    assert len(shape) == 2
+
+    arr = np.zeros((shape[0], shape[1], 3))
+    if gradient:
+        # gradient from gray to white
+        arr += np.linspace(128, 255, shape[1])[:, None]
+    im = Image.fromarray(arr.astype('uint8'))
+    im.save(filename)
+
+
 SYNTAX_ERROR_DOCSTRING = """
 SyntaxError
 ===========