使用PHP通过svg生成base64文字首字头像

使用SVG来生成文字头像

代码如下：

/**
 * 首字母头像
 * @param $text
 * @return string
 */
function letter_avatar($text)
{
    $total = unpack('L', hash('adler32', $text, true))[1];
    $hue = $total % 360;
    list($r, $g, $b) = hsv2rgb($hue / 360, 0.3, 0.9);
    $bg = "rgb({$r},{$g},{$b})";
    $color = "#ffffff";
    $first = mb_strtoupper(mb_substr($text, 0, 1));
    $src = base64_encode('<svg xmlns="http://www.w3.org/2000/svg" version="1.1" height="100" width="100"><rect fill="' . $bg . '" x="0" y="0" width="100" height="100"></rect><text x="50" y="50" font-size="50" text-copy="fast" fill="' . $color . '" text-anchor="middle" text-rights="admin" alignment-baseline="central">' . $first . '</text></svg>');
    return 'data:image/svg+xml;base64,' . $src;
}
function hsv2rgb($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)
    ];
}    
echo "<img src='".letter_avatar('泽泽社长')."' />";

代码在文章下方，原理就是，调用函数将用户名输入进去，然后使用用户名通过一些计算给svg设置个背景色，同时提取用户名第一个文字或字母作为svg的文字内容，最后想svg转为base64编码，base64编码加上data:image/svg+xml;base64,前缀就可以当做src被img标签引用了,如下就是上方代码生成的svg图片地址。

data:image/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHZlcnNpb249IjEuMSIgaGVpZ2h0PSIxMDAiIHdpZHRoPSIxMDAiPjxyZWN0IGZpbGw9InJnYigxNjAsMTgzLDIyOSkiIHg9IjAiIHk9IjAiIHdpZHRoPSIxMDAiIGhlaWdodD0iMTAwIj48L3JlY3Q+PHRleHQgeD0iNTAiIHk9IjUwIiBmb250LXNpemU9IjUwIiB0ZXh0LWNvcHk9ImZhc3QiIGZpbGw9IiNmZmZmZmYiIHRleHQtYW5jaG9yPSJtaWRkbGUiIHRleHQtcmlnaHRzPSJhZG1pbiIgYWxpZ25tZW50LWJhc2VsaW5lPSJjZW50cmFsIj7ms708L3RleHQ+PC9zdmc+

代码转自：https://pangsuan.com/p/php_base64_avatar.html