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#!/usr/bin/env python3
""" Script that checks if Pygments styles meet the WCAG color contrast standards """
import sys
import statistics
import pygments.styles
import wcag_contrast_ratio
def hex2rgb(hexstr):
hexstr = hexstr.lstrip('#')
r = int(hexstr[:2], 16) / 255
g = int(hexstr[2:4], 16) / 255
b = int(hexstr[4:], 16) / 255
return (r, g, b)
total_wcag_fails = 0
styles = []
for name in pygments.styles.get_all_styles():
style = pygments.styles.get_style_by_name(name)
bgcolor = hex2rgb(style.background_color)
contrasts = [
(
wcag_contrast_ratio.rgb(
bgcolor,
hex2rgb(style['color'] or '#000000')
# we default to black because browsers also do
),
ttype
) for ttype, style in style.list_styles()
]
if len(contrasts) == 0:
continue
styles.append(
(statistics.mean([x[0] for x in contrasts]), min([x[0] for x in contrasts]), name)
)
bad_contrasts = [c for c in contrasts if not wcag_contrast_ratio.passes_AA(c[0])]
print(f'=== {name} ===')
if len(bad_contrasts) > 0:
for contrast, ttype in sorted(bad_contrasts):
print(f'{contrast:.2f} {ttype}')
else:
print('meets AA standard')
print()
total_wcag_fails += len(bad_contrasts)
if total_wcag_fails:
print(f'found {total_wcag_fails} contrasts that fail to meet the WCAG AA standard')
print('''According to WCAG:
AA contrast is >= 4.5
AAA contrast is >= 7.0
''')
print('=== Styles ranked by contrast ===')
print(' avg min name')
for contrast, minimum, name in sorted(styles):
print(f'{contrast:4.1f} {minimum:4.1f} {name}')
sys.exit(1)
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