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$width=145;
$height = 45;
$authcode = vcaptcha_read_code('words.txt') ;
$bg = 'bg/captcha_bg3.jpg';
$img_type = 'png';
/* 验证码长度 */
$letters = strlen($authcode);
$img_bg = (function_exists('imagecreatefromjpeg') && ((imagetypes() & IMG_JPG) > 0)) ?
imagecreatefromjpeg($bg) : imagecreatefromgif($bg);
$bg_width = imagesx($img_bg);
$bg_height = imagesy($img_bg);
$img_org = ((function_exists('imagecreatetruecolor')) && PHP_VERSION >= '4.3') ?
imagecreatetruecolor($width, $height) : imagecreate($width, $height);
/* 将背景图象复制原始图象并调整大小 */
if (function_exists('imagecopyresampled') && PHP_VERSION >= '4.3') // GD 2.x
{
imagecopyresampled($img_org, $img_bg, 0, 0, 0, 0, $width, $height, $bg_width, $bg_height);
}
else // GD 1.x
{
imagecopyresized($img_org, $img_bg, 0, 0, 0, 0, $width, $height, $bg_width, $bg_height);
}
imagedestroy($img_bg);
$clr = imagecolorallocate($img_org, 255, 255, 255);
/* 绘制边框 */
imagerectangle($img_org, 0, 0, $width - 1, $height - 1, $clr);
/* 获得验证码的高度和宽度 */
$x = ($width - (imagefontwidth(5) * $letters)) / 2;
$y = ($height - imagefontheight(5)) / 2;
imagestring($img_org, 5, $x, $y, $authcode, $clr);
header('Expires: Thu, 01 Jan 1970 00:00:00 GMT');
// HTTP/1.1
header('Cache-Control: private, no-store, no-cache, must-revalidate');
header('Cache-Control: post-check=0, pre-check=0, max-age=0', false);
// HTTP/1.0
header('Pragma: no-cache');
if ($img_type == 'jpeg' && function_exists('imagecreatefromjpeg'))
{
header('Content-type: image/jpeg');
imageinterlace($img_org, 1);
imagejpeg($img_org, false, 95);
}
else
{
header('Content-type: image/png');
imagepng($img_org);
}
imagedestroy($img_org);
function vcaptcha_read_code($wordlist_file)
{
$fp = @fopen($wordlist_file, 'rb');
if (!$fp) return false;
$fsize = filesize($wordlist_file);
if ($fsize < 32) return false; // too small of a list to be effective
if ($fsize < 128) {
$max = $fsize; // still pretty small but changes the range of seeking
} else {
$max = 128;
}
fseek($fp, rand(0, $fsize - $max), SEEK_SET);
$data = fread($fp, 128); // read a random 128 bytes from file
fclose($fp);
$data = preg_replace("/r?n/", "n", $data);
$start = strpos($data, "n", rand(0, 100)) + 1; // random start position
$end = strpos($data, "n", $start); // find end of word
return strtolower(substr($data, $start, $end - $start)); // return substring in 128 bytes
}
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