[Docs] Replace PNG/ICO images with SVG

changelog.d/2867.doc.1.rst

@@ -0,0 +1 @@
+PNG/ICO images replaced with SVG in the docs.

changelog.d/2867.doc.2.rst

@@ -0,0 +1 @@
+Added support to SVG "favicons" via "in-tree" Sphinx extension.

docs/_ext/_custom_icons.py

@@ -0,0 +1,58 @@
+"""'In-tree' sphinx extension to add icons/favicons to documentation"""
+import os
+from sphinx.util.fileutil import copy_asset_file
+
+
+IMAGES_DIR = "_images"  # same used by .. image:: and .. picture::
+
+
+def _prepare_image(pathto, confdir, outdir, icon_attrs):
+    """Copy icon files to the ``IMAGES_DIR`` and return a modified version of
+    the icon attributes dict replacing ``file`` with the correct ``href``.
+    """
+    icon = icon_attrs.copy()
+    src = os.path.join(confdir, icon.pop("file"))
+    if not os.path.exists(src):
+        raise FileNotFoundError(f"icon {src!r} not found")
+
+    dest = os.path.join(outdir, IMAGES_DIR)
+    copy_asset_file(src, dest)  # already compares if dest exists and is uptodate
+
+    asset_name = os.path.basename(src)
+    icon["href"] = pathto(f"{IMAGES_DIR}/{asset_name}", resource=True)
+    return icon
+
+
+def _link_tag(attrs):
+    return "<link " + " ".join(f'{k}="{v}"' for k, v in attrs.items()) + "/>"
+
+
+def _add_icons(app, _pagename, _templatename, context, doctree):
+    """Add multiple "favicons", not limited to PNG/ICO files"""
+    # https://evilmartians.com/chronicles/how-to-favicon-in-2021-six-files-that-fit-most-needs
+    # https://caniuse.com/link-icon-svg
+    try:
+        pathto = context['pathto']
+    except KeyError as ex:
+        msg = f"{__name__} extension is supposed to be call in HTML contexts"
+        raise ValueError(msg) from ex
+
+    if doctree and "icons" in app.config:
+        icons = [
+            _prepare_image(pathto, app.confdir, app.outdir, icon)
+            for icon in app.config["icons"]
+        ]
+        context["metatags"] += "\n".join(_link_tag(attrs) for attrs in icons)
+
+
+def setup(app):
+    images_dir = os.path.join(app.outdir, IMAGES_DIR)
+    os.makedirs(images_dir, exist_ok=True)
+
+    app.add_config_value("icons", None, "html")
+    app.connect("html-page-context", _add_icons)
+
+    return {
+        'parallel_read_safe': True,
+        'parallel_write_safe': True,
+    }

docs/conf.py

@@ -1,3 +1,6 @@
+import os
+import sys
+
 extensions = ['sphinx.ext.autodoc', 'jaraco.packaging.sphinx', 'rst.linker']
 
 master_doc = "index"
@@ -101,8 +104,7 @@
 
 # HTML theme
 html_theme = 'furo'
-html_logo = "images/logo.png"
-html_favicon = "images/favicon.ico"
+html_logo = "images/logo.svg"
 
 html_theme_options = {
     "sidebar_hide_name": True,
@@ -171,3 +173,26 @@
 towncrier_draft_include_empty = False
 
 extensions += ['jaraco.tidelift']
+
+# Add icons (aka "favicons") to documentation
+sys.path.append(os.path.join(os.path.dirname(__file__), '_ext'))
+extensions += ['_custom_icons']
+
+# List of dicts with <link> HTML attributes
+# as defined in https://developer.mozilla.org/en-US/docs/Web/HTML/Element/link
+# except that ``file`` gets replaced with the correct ``href``
+icons = [
+    {  # "Catch-all" goes first, otherwise some browsers will overwrite
+        "rel": "icon",
+        "type": "image/svg+xml",
+        "file": "images/logo-symbol-only.svg",
+        "sizes": "any"
+    },
+    {  # Version with thicker strokes for better visibility at smaller sizes
+        "rel": "icon",
+        "type": "image/svg+xml",
+        "file": "images/favicon.svg",
+        "sizes": "16x16 24x24 32x32 48x48"
+    },
+    # rel="apple-touch-icon" does not support SVG yet
+]

docs/images/README.rst

@@ -35,7 +35,7 @@ on the circumstances:
 
 The following image illustrate these alternatives:
 
-.. image:: logo-demo-editable-inkscape.png
+.. image:: logo-demo.svg
    :align: center
 
 Please refer to the SVG files in the `setuptools repository`_ for the specific