Add a logo to the C++ docs

This requires working around a bug in sphinx and the rtd theme, hence
the git pinning.

api/sixtyfps-cpp/docs/Pipfile

@@ -6,9 +6,10 @@ verify_ssl = true
 [dev-packages]
 
 [packages]
-sphinx = "*"
 breathe = "*"
-sphinx-rtd-theme = "*"
+# Upstream sphinx and sphinx-rtd-theme have a bug in not supporting html_logo urls, pull in prospective fix
+sphinx-rtd-theme = {editable = true, ref = "logo-url-fix", git = "https://github.com/tronical/sphinx_rtd_theme.git"}
+sphinx = {editable = true, ref = "logo-url-fix", git = "https://github.com/tronical/sphinx.git"}
 exhale = "*"
 recommonmark = "*"
 sphinx-markdown-tables = "*"

api/sixtyfps-cpp/docs/_static/theme_tweak.css

@@ -7,3 +7,7 @@
     max-width: 100%;
     overflow: visible;
 }
+
+img.logo {
+    max-height: 70px;
+}

api/sixtyfps-cpp/docs/conf.py

@@ -76,5 +76,7 @@ html_static_path = ['_static']
 
 html_show_sourcelink = False
 
+html_logo = "https://sixtyfps.io/resources/logo.drawio.svg"
+
 def setup(app):
     app.add_css_file('theme_tweak.css')