php图片验证码类

baiyunjn

<?php
/**
* 图片验证码类
* 生成图片类型验证码，验证码包含数字和大写字母，session中存放md5加密后的验证码
*
* 使用方法：
* $captcha = new Catpcha();
* $captcha->buildAndExportImage();
*
* 作          者: luojing
* 创建时间: 2013-3-27 上午11:42:12
*/
class Captcha {
private $width;//宽度
private $height; //高度
private $codeNum;//验证码字符数量
private $image;//验证码图像资源
private $sessionKey;//session中保存的名字
private $captcha;//验证码字符串
const charWidth = 10;//单个字符宽度,根据输出字符大小而变
/**
* 创建验证码类，初始化相关参数
* @param  $width 图片宽度
* @param  $height 图片高度
* @param  $codeNum 验证码字符数量
* @param  $sessionKey session中保存的名字
*/
function __construct($width = 50, $height = 20, $codeNum = 4, $sessionKey = 'captcha') {
$this->width = $width;
$this->height = $height;
$this->codeNum = $codeNum;
$this->sessionKey = $sessionKey;
//保证最小高度和宽度
if($height < 20) {
$this->height = 20;
}
if($width < ($codeNum * self::charWidth + 10)) {//左右各保留5像素空隙
$this->width = $codeNum * self::charWidth + 10;
}
}
/**
* 构造并输出验证码图片
*/
public  function buildAndExportImage() {
$this->createImage();
$this->setDisturb();
$this->setCaptcha();
$this->exportImage();
}
/**
* 构造图像，设置底色
*/
private function createImage() {
//创建图像
$this->image = imagecreatetruecolor($this->width, $this->height);  
//创建背景色
$bg = imagecolorallocate($this->image, mt_rand(220, 255), mt_rand(220, 255), mt_rand(220, 255));  
//填充背景色
imagefilledrectangle($this->image, 0, 0, $this->width - 1, $this->height - 1, $bg);
}
/**
* 设置干扰元素
*/
private function setDisturb() {
//设置干扰点
for($i = 0; $i < 150; $i++) {
$color = imagecolorallocate($this->image, mt_rand(150, 200),  mt_rand(150, 200),  mt_rand(150, 200));
imagesetpixel($this->image, mt_rand(5, $this->width - 10), mt_rand(5, $this->height - 3), $color);
}
//设置干扰线
for($i = 0; $i < 10; $i++) {
$color = imagecolorallocate($this->image, mt_rand(150, 220), mt_rand(150, 220), mt_rand(150, 220));
imagearc($this->image, mt_rand(-10, $this->width), mt_rand(-10, $this->height), mt_rand(30, 300), mt_rand(20, 200), 55, 44, $color);
}
//创建边框色
$border = imagecolorallocate($this->image, mt_rand(0, 50), mt_rand(0, 50), mt_rand(0, 50));
//画边框
imagerectangle($this->image, 0, 0, $this->width - 1, $this->height - 1, $border);
}
/**
* 产生并绘制验证码
*/
private function setCaptcha() {
$str = '23456789ABCDEFGHJKLMNPQRSTUVWXYZ';
//生成验证码字符
for($i = 0; $i < $this->codeNum; $i++) {
$this->captcha .= $str{mt_rand(0, strlen($str) - 1)};
}
//绘制验证码
for($i = 0; $i < strlen($this->captcha); $i++) {
$color = imagecolorallocate($this->image, mt_rand(0, 200), mt_rand(0, 200), mt_rand(0, 200));
$x = floor(($this->width - 10)/$this->codeNum);
$x = $x*$i + floor(($x-self::charWidth)/2) + 5;
$y = mt_rand(2, $this->height - 20);
imagechar($this->image, 5, $x, $y, $this->captcha{$i}, $color);
}
}
/*
* 输出图像,验证码保存到session中
*/
private function exportImage() {
if(imagetypes() & IMG_GIF){
header('Content-type:image/gif');
imagegif($this->image);
} else if(imagetypes() & IMG_PNG){
header('Content-type:image/png');  
imagepng($this->iamge);
} else if(imagetypes() & IMG_JPEG) {
header('Content-type:image/jpeg');  
imagepng($this->iamge);
} else {
imagedestroy($this->image);
die("Don't support image type!");
}
//将验证码信息保存到session中，md5加密
if(!isset($_SESSION)){
session_start();
}
$_SESSION[$this->sessionKey] = md5($this->captcha);
imagedestroy($this->image);  
}
function __destruct() {
unset($this->width, $this->height, $this->codeNum,$this->captcha);
}
}