Some styles have bad contrasts #1718
Description
Currently some styles have bad contrasts, as seen in the official PIP documentation:
To make pygments more accessible, I think we should:
- Prohibit contrast degradation for styles in the CI (Prohibit contrast degradation for styles via test #1919)
- Make the default style meet WCAG AA (Make default style meet WCAG AA #1940).
- Promote styles meeting WCAG AA in the styles gallery (Promote styles meeting WCAG AA in styles gallery #1954)
- Fix completely unreadable dark styles & slightly boost sas style (Fix unreadable dark styles by adding missing colors #1955)
- Promote styles meeting WCAG AA in the demo (Make the demo awesome #1999)
- Track down remaining unreadable contrasts (Tracebacks unreadable on dark styles #1526)
- When it doesn't conflict with other style colors, make
Token.Commentstyles meet WCAG AA.
Original issue description
I wrote a small Python script to check how Pygments styles fare when judged according to the WCAG contrast standard.
The summary of my script is:
found 840 contrasts that fail to meet the WCAG AA standard
According to WCAG:
AA contrast is >= 4.5
AAA contrast is >= 7.0
=== Styles ranked by contrast ===
avg min name
3.4 2.5 solarized-light
4.2 1.4 stata-dark
4.3 2.8 solarized-dark
5.5 1.3 paraiso-light
6.2 1.3 paraiso-dark
6.3 1.0 rrt
7.0 1.0 inkpot
7.3 1.7 friendly
7.5 1.6 perldoc
7.5 2.1 native
7.6 1.8 emacs
7.8 1.3 vim
7.9 1.4 monokai
8.0 1.4 manni
8.7 3.1 lovelace
8.7 1.8 default
8.9 2.6 arduino
9.2 1.9 autumn
9.3 1.9 pastie
9.6 1.0 rainbow_dash
9.9 1.9 trac
10.1 1.4 murphy
10.4 1.0 tango
10.7 1.9 fruity
10.7 1.9 colorful
11.1 1.9 sas
13.0 2.5 abap
13.2 1.9 stata
13.2 1.9 stata-light
13.8 1.9 borland
13.9 5.1 xcode
14.4 3.6 igor
14.7 3.5 algol
14.7 3.5 algol_nu
15.7 3.6 vs
21.0 21.0 bw
My script also reports which rules don't meet the AA standard per style sorted by contrast, e.g. for the default style:
=== default ===
1.81 Token.Text.Whitespace
2.63 Token.Name.Label
2.68 Token.Name.Entity
3.28 Token.Generic.Inserted
3.34 Token.Generic.Output
3.34 Token.Comment.Preproc
3.36 Token.Name.Attribute
3.68 Token.Literal.String.Interpol
3.68 Token.Literal.String.Regex
3.76 Token.Generic.Error
3.93 Token.Literal.String.Escape
4.28 Token.Comment
4.28 Token.Comment.Hashbang
4.28 Token.Comment.Multiline
4.28 Token.Comment.PreprocFile
4.28 Token.Comment.Single
4.28 Token.Comment.Special
4.34 Token.Name.Exception
I am not saying that every Pygments style needs to have an AA contrast for every token type, but I think at least the default style should, since it's probably the most used one. If you want to I can send a PR to add my script into the scripts directory.
To improve the accessibility long term, I think it would make sense to incorporate the script into your CI pipeline with a given minimum contrast, making the pipeline fail if any style fails to meet this minimum. As the worst contrasts are improved this minimum contrast could then be gradually raised.