WCAG compliance levels for accessibility standards.

• AA: Standard level (4.5:1 for normal text, 3:1 for large text)
• AAA: Enhanced level (7:1 for normal text, 4.5:1 for large text)
• NotCompliant: Does not meet any WCAG contrast requirements

Text size categories that affect contrast requirements.

• Normal: Regular text size (requires higher contrast ratios)
• Large: Large text (18pt+ or 14pt+ bold, requires lower contrast ratios)

Calculate the contrast ratio between two colors according to WCAG guidelines.

The contrast ratio ranges from 1:1 (no contrast) to 21:1 (maximum contrast). It's calculated using the formula: (L1 + 0.05) / (L2 + 0.05) where L1 is the lighter color's relative luminance and L2 is the darker color's relative luminance.

For semi-transparent colors, they are first blended with the background color before calculating the contrast ratio, as per WCAG guidelines.

contrastRatio (rgb 0 0 0) (rgb 1 1 1) --> 21.0 (black on white)


contrastRatio (rgb 0.5 0.5 0.5) (rgb 1 1 1) --> ~3.98 (gray on white)


contrastRatio (rgba 0 0 0 0.5) (rgb 1 1 1) --> ~3.98 (50% black blended with white)

Check if two colors meet WCAG AA contrast requirements for a given text size.

    meetsWcagAA Normal (rgb 0 0 0) (rgb 1 1 1) --> True (21:1 > 4.5:1)
    meetsWcagAA Normal (rgb 0.7 0.7 0.7) (rgb 1 1 1) --> False (~2.8:1 < 4.5:1)
    meetsWcagAA Large (rgb 0.7 0.7 0.7) (rgb 1 1 1) --> True (~2.8:1 > 3:1)

Check if two colors meet WCAG AAA contrast requirements for a given text size.

    meetsWcagAAA Normal (rgb 0 0 0) (rgb 1 1 1) --> True (21:1 > 7:1)
    meetsWcagAAA Normal (rgb 0.7 0.7 0.7) (rgb 1 1 1) --> False (~2.8:1 < 7:1)
    meetsWcagAAA Large (rgb 0.3 0.3 0.3) (rgb 1 1 1) --> True (~5.7:1 > 4.5:1)

Get the highest WCAG compliance level that two colors meet for both normal and large text sizes.

Returns a record with the compliance levels for both text sizes.

wcagLevel (rgb 0 0 0) (rgb 1 1 1)
--> { normal = AAA, large = AAA }


wcagLevel (rgb 0.5 0.5 0.5) (rgb 1 1 1)
--> { normal = AA, large = AAA }


wcagLevel (rgb 0.8 0.8 0.8) (rgb 1 1 1)
--> { normal = NotCompliant, large = NotCompliant }

Format a contrast ratio as a string with ratio notation.

    formatContrastRatio 4.5 --> "4.5:1"
    formatContrastRatio 21.0 --> "21:1"