dedecms 验证码图片

// 生成验证码图片
function create_captcha() {
    $width = 100;
    $height = 40;
    $img = imagecreatetruecolor($width, $height);
    $bg_color = imagecolorallocate($img, 255, 255, 255);
    imagefill($img, 0, 0, $bg_color);

    $captcha = substr(md5(uniqid(mt_rand(), true)), 0, 4);
    $_SESSION['captcha'] = $captcha; // 保存验证码到Session

    $font_color = imagecolorallocate($img, 0, 0, 0);
    imagettftext($img, 20, 0, 10, 30, $font_color, 'arial.ttf', $captcha);

    for ($i = 0; $i < 5; $i++) {
        $line_color = imagecolorallocate($img, mt_rand(0, 255), mt_rand(0, 255), mt_rand(0, 255));
        imageline($img, mt_rand(0, $width), mt_rand(0, $height), mt_rand(0, $width), mt_rand(0, $height), $line_color);
    }

    header('Content-type: image/png');
    imagepng($img);
    imagedestroy($img);
}