<?php
class CCheckCodeFile{
	private $mCheckCodeNum = 4;//验证码位数
	private $mCheckCode = '0123456789';//产生的验证码
	private $mCheckImageWidth = '65';//验证码的图片宽度
	private $mCheckImageHeight = '20';//验证码的图片宽度
	//输出验证码图片
	public function OutCheckImage(){
		header("Content-type:image/png");//输出图象头信息
		$im = imagecreate($this->mCheckImageWidth,$this->mCheckImageHeight);//建立图象
		$black = imagecolorallocate($im,255,255,255);//建立黑色标志符
		$white = imagecolorallocate($im,0,0,0);//建立白色标志符
		$gray = imagecolorallocate($im,100,100,100);//建立灰色标志符
		imagefill($im,80,30,$black);//填充图象
		for($i=0;$i<50;$i++){
			$randcolor=imagecolorallocate($im,rand(100,255),rand(100,255),rand(100,255));//建立一个随机图象颜色标志符
			imagesetpixel($im, rand(0,$this->mCheckImageWidth),rand(0,$this->mCheckImageHeight),$randcolor);//用上一行建立的标志符描点，点的坐标为随机
		}
//		for($i=0;$i<5;$i++){
//			imageline($im,rand(0,$this->mCheckImageWidth),rand(0,$this->mCheckImageHeight),rand(0,$this->mCheckImageWidth),rand(0,$this->mCheckImageHeight),$gray);//以随机坐标画线
//		}
		for($i=0;$i<=$this->mCheckCodeNum;$i++){
			$authnum.=substr($this->mCheckCode,rand(0,9),1);//建立验证字符串
		}
		$_SESSION['num']=strtolower($authnum);//把字符串写入SESSION以待验证
		$x=rand(2,20);
		$y=rand(2,6);
		imagestring($im,5,$x,$y,$authnum,$white);//把字符串写入图片
		imagepng($im);//输出图片
		imagedestroy($im);//注销图片资源
	}
}
session_start();
if($_SESSION['num']){
unset($_SESSION['num']);//注销上一次的图片验证码
}
$code_image = new CCheckCodeFile;
$code_image ->OutCheckImage();
?>