php验证码

<?php

/**

* vCode(m,n,x,y) m个数字  显示大小为n   边宽x   边高y

* http://blog.qita.in

* 自己改写记录session $code

*/

session_start();

vCode(4, 15); //4个数字，显示大小为15

function vCode($num = 4, $size = 20, $width = 0, $height = 0) {

!$width && $width = $num * $size * 4 / 5 + 5;

!$height && $height = $size + 10;

// 去掉了 0 1 O l 等

$str = "23456789abcdefghijkmnpqrstuvwxyzABCDEFGHIJKLMNPQRSTUVW";

$code = '';

for ($i = 0; $i < $num; $i++) {

$code .= $str[mt_rand(0, strlen($str)-1)];

}

// 画图像

$im = imagecreatetruecolor($width, $height);

// 定义要用到的颜色

$back_color = imagecolorallocate($im, 235, 236, 237);

$boer_color = imagecolorallocate($im, 118, 151, 199);

$text_color = imagecolorallocate($im, mt_rand(0, 200), mt_rand(0, 120), mt_rand(0, 120));

// 画背景

imagefilledrectangle($im, 0, 0, $width, $height, $back_color);

// 画边框

imagerectangle($im, 0, 0, $width-1, $height-1, $boer_color);

// 画干扰线

for($i = 0;$i < 5;$i++) {

$font_color = imagecolorallocate($im, mt_rand(0, 255), mt_rand(0, 255), mt_rand(0, 255));

imagearc($im, mt_rand(- $width, $width), mt_rand(- $height, $height), mt_rand(30, $width * 2), mt_rand(20, $height * 2), mt_rand(0, 360), mt_rand(0, 360), $font_color);

}

// 画干扰点

for($i = 0;$i < 50;$i++) {

$font_color = imagecolorallocate($im, mt_rand(0, 255), mt_rand(0, 255), mt_rand(0, 255));

imagesetpixel($im, mt_rand(0, $width), mt_rand(0, $height), $font_color);

}

// 画验证码

@imagefttext($im, $size , 0, 5, $size + 3, $text_color, 'c:\\WINDOWS\\Fonts\\simsun.ttc', $code);

$_SESSION["VerifyCode"]=$code;

header("Cache-Control: max-age=1, s-maxage=1, no-cache, must-revalidate");

header("Content-type: image/png;charset=gb2312");

imagepng($im);

imagedestroy($im);

}

?>