dedecms获取随机验证码

if (!echo_validate_image($config))
{
    // 如果不成功则初始化一个默认验证码
    @session_start();
    $_SESSION['securimage_code_value'] = strtolower('abcd');
    $im = @imagecreatefromjpeg(dirname(__FILE__).'/data/vdcode.jpg');
    header("Pragma:no-cache\r\n");
    header("Cache-Control:no-cache\r\n");
    header("Expires:0\r\n");
    imagejpeg($im);
    imagedestroy($im);
}

function echo_validate_image( $config = array() )
{
    @session_start();

    if ( !function_exists('imagettftext') )
    {
        return false;
    }

    //主要参数
    $font_size   = isset($config['font_size']) ? $config['font_size'] : 14;
    $img_height  = isset($config['img_height']) ? $config['img_height'] : 24;
    $img_width   = isset($config['img_width']) ? $config['img_width'] : 68;
    $font_file   = isset($config['font_file']) ? $config['font_file'] : PATH_DATA.'/data/font/'.mt_rand(1,3).'.ttf';
    $use_boder   = isset($config['use_boder']) ? $config['use_boder'] : TRUE;
    $filter_type = isset($config['filter_type']) ? $config['filter_type'] : 0;

    //创建图片，并设置背景色
    $im = @imagecreate($img_width, $img_height);
    imagecolorallocate($im, 255,255,255);

    //文字随机颜色
    $fontColor[]  = imagecolorallocate($im, 0x15, 0x15, 0x15);
    $fontColor[]  = imagecolorallocate($im, 0x95, 0x1e, 0x04);
    $fontColor[]  = imagecolorallocate($im, 0x93, 0x14, 0xa9);
    $fontColor[]  = imagecolorallocate($im, 0x12, 0x81, 0x0a);
    $fontColor[]  = imagecolorallocate($im, 0x06, 0x3a, 0xd5);

    //获取随机字符
    $rndstring  = '';
    if ($config['word_type'] != 3)
    {
        for($i=0; $i<4; $i++)
        {
            if ($config['word_type'] == 1)
            {
                $c = chr(mt_rand(48, 57));
            } else if($config['word_type'] == 2)
            {
                $c = chr(mt_rand(65, 90));
                if( $c=='I' ) $c = 'P';
                if( $c=='O' ) $c = 'N';
            }
            $rndstring .= $c;
        }
    } else {
        $chars='abcdefghigklmnopqrstuvwxwyABCDEFGHIGKLMNOPQRSTUVWXWY0123456789';
        $rndstring='';
        $length = rand(4,4);
        $max = strlen($chars) - 1;
        for($i = 0; $i < $length; $i++) {
            $rndstring .= $chars[mt_rand(0, $max)];
        }
    }

    $_SESSION['securimage_code_value'] = strtolower($rndstring);

    $rndcodelen = strlen($rndstring);

    //背景横线
    $lineColor1 = imagecolorallocate($im, 0xda, 0xd9, 0xd1);
    for($j=3; $j<=$img_height-3; $j=$j+3)
    {
        imageline($im, 2, $j, $img_width - 2, $j, $lineColor1);
    }

    //背景竖线
    $lineColor2 = imagecolorallocate($im, 0xda,0xd9,0xd1);
    for($j=2;$j<100;$j=$j+6)
    {
        imageline($im, $j, 0, $j+8, $img_height, $lineColor2);
    }

    //画边框
    if( $use_boder && $filter_type == 0 )
    {
        $bordercolor = imagecolorallocate($im, 0x9d, 0x9e, 0x96);
        imagerectangle($im, 0, 0, $img_width-1, $img_height-1, $bordercolor);
    }

    //输出文字
    $lastc = '';
    for($i=0;$i<$rndcodelen;$i++)
    {
        $bc = mt_rand(0, 1);
        $rndstring[$i] = strtoupper($rndstring[$i]);
        $c_fontColor = $fontColor[mt_rand(0,4)];
        $y_pos = $i==0 ? 4 : $i*($font_size+2);
        $c = mt_rand(0, 15);
        @imagettftext($im, $font_size, $c, $y_pos, 19, $c_fontColor, $font_file, $rndstring[$i]);
        $lastc = $rndstring[$i];
    }

    //图象效果
    switch($filter_type)
    {
        case 1:
            imagefilter ( $im, IMG_FILTER_NEGATE);
            break;
        case 2:
            imagefilter ( $im, IMG_FILTER_EMBOSS);
            break;
        case 3:
            imagefilter ( $im, IMG_FILTER_EDGEDETECT);
            break;
        default:
            break;
    }

    header("Pragma:no-cache\r\n");
    header("Cache-Control:no-cache\r\n");
    header("Expires:0\r\n");

    //输出特定类型的图片格式，优先级为 gif -> jpg ->png
    //dump(function_exists("imagejpeg"));

    if(function_exists("imagejpeg"))
    {
        header("content-type:image/jpeg\r\n");
        imagejpeg($im);
    }
    else
    {
        header("content-type:image/png\r\n");
        imagepng($im);
    }
    imagedestroy($im);
    exit();
}