簡單好用的PHP驗證碼類

/**


@PHP驗證碼類
使用方法：
$image=new Captcha();
$image->config('寬度','高度','字符個數','驗證碼session索引');
$image->create();//這樣就會向瀏覽器輸出一張圖片
//http://blog.ddian.cn
//所有參數都可以省略，
默認是：寬80 高20 字符數4 驗證碼session索引captcha_code
第四個參數即把驗證碼存到$_SESSION['captcha_code']
最簡單使用示例:
$image=new Captcha();
$image->create();//這樣就會向瀏覽器輸出一張圖片
/
class Captcha
{
private $width=80,$height=20,$codenum=4;
public $checkcode; //產生的驗證碼
private $checkimage; //驗證碼圖片
private $disturbColor = ''; //干擾像素
private $session_flag='captcha_code';//存到session中的索引
//嘗試開始session
function __construct(){
@session_start();
}
/
參數：（寬度，高度，字符個數）
/
function config($width='80',$height='20',$codenum='4',$session_flag='captcha_code')
{
$this->width=$width;
$this->height=$height;
$this->codenum=$codenum;
$this->session_flag=$session_flag;
}
function create()
{
//輸出頭
$this->outFileHeader();
//產生驗證碼
$this->createCode();
//產生圖片
$this->createImage();
//設置干擾像素
$this->setDisturbColor();
//往圖片上寫驗證碼
$this->writeCheckCodeToImage();
imagepng($this->checkimage);
imagedestroy($this->checkimage);
$_SESSION[$this->session_flag]=$this->checkcode;
}
/
@brief 輸出頭
*/
private function outFileHeader()
{
header ("Content-type: image/png");
}
/**
產生驗證碼
*/
private function createCode()
{
$this->checkcode = strtoupper(substr(md5(rand()),0,$this->codenum));
}
/**
產生驗證碼圖片
*/
private function createImage()
{
$this->checkimage = @imagecreate($this->width,$this->height);
$back = imagecolorallocate($this->checkimage,255,255,255);
$border = imagecolorallocate($this->checkimage,0,0,0);
imagefilledrectangle($this->checkimage,0,0,$this->width - 1,$this->height - 1,$back); // 白色底
imagerectangle($this->checkimage,0,0,$this->width - 1,$this->height - 1,$border); // 黑色邊框
}
/**
設置圖片的干擾像素
/
private function setDisturbColor()
{
for ($i=0;$i<=200;$i++)
{
$this->disturbColor = imagecolorallocate($this->checkimage, rand(0,255), rand(0,255), rand(0,255));
imagesetpixel($this->checkimage,rand(2,128),rand(2,38),$this->disturbColor);
}
}
/**
在驗證碼圖片上逐個畫上驗證碼
/
private function writeCheckCodeToImage()
{
for ($i=0;$i<$this->codenum;$i++)
{
$bg_color = imagecolorallocate ($this->checkimage, rand(0,255), rand(0,128), rand(0,255));
$x = floor($this->width/$this->codenum)*$i;
$y = rand(0,$this->height-15);
imagechar ($this->checkimage, rand(5,8), $x+5, $y, $this->checkcode[$i], $bg_color);
}
}
function __destruct()
{
unset($this->width,$this->height,$this->codenum,$this->session_flag);
}
}
?>
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