Sort styles in gallery by background luminance

1 files changed, 10 insertions, 0 deletions

diff --git a/doc/conf.py b/doc/conf.py
index 00900d71..18cf4736 100644
--- a/doc/conf.py
+++ b/doc/conf.py
@@ -237,6 +237,7 @@ def pg_context(app, pagename, templatename, ctx, event_arg):
         ctx['styles_sub_aa'] = []
         for style in pygments.styles.get_all_styles():
             aa = min_contrasts[style] >= test_contrasts.WCAG_AA_CONTRAST
+            bg_r, bg_g, bg_b = test_contrasts.hex2rgb(pygments.styles.get_style_by_name(style).background_color)
             ctx['styles_aa' if aa else 'styles_sub_aa'].append(
                 dict(
                     name=style,
@@ -245,8 +246,17 @@ def pg_context(app, pagename, templatename, ctx, event_arg):
                         lexer,
                         pygments.formatters.HtmlFormatter(noclasses=True, style=style),
                     ),
+                    # from https://en.wikipedia.org/wiki/Relative_luminance
+                    bg_luminance=(0.2126*bg_r + 0.7152*bg_g + 0.0722*bg_b)
                 )
             )
+        # sort styles according to their background luminance (light styles first)
+        # if styles have the same background luminance sort them by their name
+        # the default style is always displayed first
+        default_style = ctx['styles_aa'].pop(0)
+        ctx['styles_aa'].sort(key=lambda s: (-s['bg_luminance'], s['name']))
+        ctx['styles_aa'].insert(0, default_style)
+        ctx['styles_sub_aa'].sort(key=lambda s: (-s['bg_luminance'], s['name']))
 
 
 def setup(app):