Small library to find valid color combinations for a given contrast threshold. The contrast calculation algorithm is based on the WCAG 2.0.

Using composer:

composer require davidgorges/color-contrast

    use ColorContrast\ColorContrast;

    /* ... */
    
    $contrast = new ColorContrast();
    $contrast->addColors(0xff0000, 0x002200, 0x0022ff, 0xffffff);
    $combinations = $contrast->getCombinations(ColorContrast::MIN_CONTRAST_AAA);
    foreach ($combinations as $combination) {
        printf("#%s on the Background color #%s has a contrast value of %f \n", $combination->getForeground(), $combination->getBackground(), $combination->getContrast());
    }

this would output:

    #FFFFFF on the Background color #002200 has a contrast value of 17.949476
    #FFFFFF on the Background color #0022FF has a contrast value of 8.033817
    #002200 on the Background color #FFFFFF has a contrast value of 17.949476
    #0022FF on the Background color #FFFFFF has a contrast value of 8.033817

    $contrast = new ColorContrast();
    $complimentary = $contrast->complimentaryTheme('#ffffff'); // returns ColorContrast::DARK to indicate you should use a dark color on this background
    
    if($complimentary == ColorContrast::LIGHT) 
    {
        // Use a light font
    } elseif($complimentary == ColorContrast::DARK) 
    {
        // use a dark font
    }

• Calculating Color Contrast with PHP by Andreas Gohr
• jxnblk/colorable JavaScript Library that inspired ColorContrast heavily

The MIT License (MIT)

Copyright (c) 2015 David Gorges

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

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