Add themed_figure extension and continue next Command Queue chapter

Author: eliemichel

_extensions/themed_figure.py

@@ -0,0 +1,65 @@
+from typing import List
+
+from docutils import nodes
+from docutils.nodes import Node, Element
+from docutils.statemachine import StringList
+from docutils.parsers.rst.directives.images import Figure
+
+from sphinx.util.docutils import SphinxDirective
+from sphinx.application import Sphinx
+
+from copy import deepcopy
+
+#############################################################
+
+def findNodeWithType(target_type, node_list):
+    for n in node_list:
+        if isinstance(n, target_type):
+            return n
+
+#############################################################
+
+class ThemedFigureDirective(Figure):
+    """
+    A figure that switches depending on the dark/light theme
+    """
+
+    def run(self) -> List[Node]:
+        url_template = self.arguments[0]
+        self.arguments[0] = url_template.replace("{theme}", "light")
+        
+        node_list = super().run()
+
+        figure_node = findNodeWithType(nodes.figure, node_list)
+        if not figure_node:
+            print(node_list)
+            raise Exception("Could not find generated figure in themed-figure")
+
+        light_image_node = findNodeWithType(nodes.image, figure_node)
+        if not light_image_node:
+            print(figure_node)
+            raise Exception("Could not find generated image in themed-figure")
+
+        # Create dark copy
+        dark_image_node = deepcopy(light_image_node)
+        dark_image_node['uri'] = url_template.replace("{theme}", "dark")
+
+        # Add class
+        light_image_node['classes'].append("only-light")
+        dark_image_node['classes'].append("only-dark")
+
+        # Insert dark image after light image
+        index = figure_node.index(light_image_node)
+        figure_node.insert(index + 1, dark_image_node)
+
+        return node_list
+
+#############################################################
+
+def setup(app: Sphinx) -> None:
+    app.add_directive("themed-figure", ThemedFigureDirective)
+    return {
+        'version': '0.1',
+        'parallel_read_safe': True,
+        'parallel_write_safe': True,
+    }

conf.py

@@ -35,9 +35,12 @@
     "sphinx_copybutton",
     "sphinx_favicon",
     "sphinx_inline_tabs",
+
+    # Internal extensions (see _extensions directory)
     "style",
     "sphinx_literate",
     "translation",
+    "themed_figure",
 ]
 
 # Add any paths that contain templates here, relative to this directory.