Add custom Sphinx extension for translating image-sg directives to …

…text

conf.py

@@ -50,7 +50,8 @@
     "sphinx.ext.intersphinx",
     "sphinx.ext.mathjax",
     "sphinx.ext.ifconfig",
-    "sphinx_gallery.gen_gallery"
+    "sphinx_gallery.gen_gallery",
+    "extension",
 ]
 
 
@@ -212,4 +213,3 @@
 
 # Example configuration for intersphinx: refer to the Python standard library.
 intersphinx_mapping = {"https://docs.pennylane.ai/en/stable/": None}
-

extension.py

@@ -0,0 +1,26 @@
+"""
+Custom Sphinx extension that adds text translation support for the ``image-sg``
+directive from Sphinx Gallery.
+"""
+
+from sphinx.errors import ExtensionError
+from sphinx.util.docutils import is_node_registered
+from sphinx_gallery.directives import imgsgnode
+
+def visit_imgsg_text(self, node):
+    """Visit function for ``imgsgnode`` nodes."""
+    self.visit_image(node)
+
+def depart_imgsg_text(self, node):
+    """Departure function for ``imgsgnode`` nodes."""
+    self.depart_image(node)
+
+def setup(app):
+    """Entrypoint for the extension."""
+    if not is_node_registered(imgsgnode):
+        raise ExtensionError("Sphinx Gallery extension must be loaded first.")
+
+    app.registry.add_translation_handlers(
+        imgsgnode,
+        text=(visit_imgsg_text, depart_imgsg_text),
+    )