生成文件后缀图片

var_dump( build_suffix_image(".MP3"));
function build_suffix_image($suffix, $background = null)
    {
        $suffix = mb_substr(strtoupper($suffix), 0, 4);
        $total = unpack('L', hash('adler32', $suffix, true))[1];
        $hue = $total % 360;
        list($r, $g, $b) = hsv2rgb($hue / 360, 0.3, 0.9);

        $background = $background ? $background : "rgb({$r},{$g},{$b})";

        $icon = <<<EOT
        <svg version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px" viewBox="0 0 512 512" style="enable-background:new 0 0 512 512;" xml:space="preserve">
            <path style="fill:#E2E5E7;" d="M128,0c-17.6,0-32,14.4-32,32v448c0,17.6,14.4,32,32,32h320c17.6,0,32-14.4,32-32V128L352,0H128z"/>
            <path style="fill:#B0B7BD;" d="M384,128h96L352,0v96C352,113.6,366.4,128,384,128z"/>
            <polygon style="fill:#CAD1D8;" points="480,224 384,128 480,128 "/>
            <path style="fill:{$background};" d="M416,416c0,8.8-7.2,16-16,16H48c-8.8,0-16-7.2-16-16V256c0-8.8,7.2-16,16-16h352c8.8,0,16,7.2,16,16 V416z"/>
            <path style="fill:#CAD1D8;" d="M400,432H96v16h304c8.8,0,16-7.2,16-16v-16C416,424.8,408.8,432,400,432z"/>
            <g><text><tspan x="220" y="380" font-size="124" font-family="Verdana, Helvetica, Arial, sans-serif" fill="white" text-anchor="middle">{$suffix}</tspan></text></g>
        </svg>
EOT;
        return $icon;
    }

 
    function hsv2rgb($h, $s, $v)
    {
        $r = $g = $b = 0;

        $i = floor($h * 6);
        $f = $h * 6 - $i;
        $p = $v * (1 - $s);
        $q = $v * (1 - $f * $s);
        $t = $v * (1 - (1 - $f) * $s);

        switch ($i % 6) {
            case 0:
                $r = $v;
                $g = $t;
                $b = $p;
                break;
            case 1:
                $r = $q;
                $g = $v;
                $b = $p;
                break;
            case 2:
                $r = $p;
                $g = $v;
                $b = $t;
                break;
            case 3:
                $r = $p;
                $g = $q;
                $b = $v;
                break;
            case 4:
                $r = $t;
                $g = $p;
                $b = $v;
                break;
            case 5:
                $r = $v;
                $g = $p;
                $b = $q;
                break;
        }

        return [
            floor($r * 255),
            floor($g * 255),
            floor($b * 255)
        ];
    }