//获取字符的验证码， 用于保存在服务器中
function getcode() {
return $this->code;
}

//输出图像
function outimg() {
//创建背景 (颜色， 大小， 边框)
$this->createback();

//画字 (大小， 字体颜色)
$this->outstring();

//干扰元素(点， 线条)

$this->setdisturbcolor();
//输出图像
$this->printimg();
}

//创建背景
private function createback() {
//创建资源
$this->img = imagecreatetruecolor($this->width,$this->height);
//设置随机的背景颜色
$bgcolor = imagecolorallocate($this->img,rand(225,255),255));
//设置背景填充
imagefill($this->img,$bgcolor);
//画边框
$bordercolor = imagecolorallocate($this->img,0);

imagerectangle($this->img,$this->width-1,$this->height-1,$bordercolor);

}

//画字
private function outstring() {
for($i=0; $i<$this->num; $i++) {

$color= imagecolorallocate($this->img,rand(0,128),128)); 

$fontsize=rand(3,5); //字体大小

$x = 3+($this->width/$this->num)*$i; //水平位置
$y = rand(0,imagefontheight($fontsize)-3);

//画出每个字符
imagechar($this->img,$fontsize,$x,$y,$this->code{$i},$color);

}
}

//设置干扰元素
private function setdisturbcolor() {
//加上点数
for($i=0; $i<100; $i++) {
$color= imagecolorallocate($this->img,255));
imagesetpixel($this->img,rand(1,$this->width-2),$this->height-2),$color);
}

//加线条
for($i=0; $i<10; $i++) {
$color= imagecolorallocate($this->img,255));
imagearc($this->img,rand(-10,$this->width+10),$this->height+10),rand(30,300),55,44,$color);
}
}

//输出图像
private function printimg() {
if (imagetypes() & IMG_GIF) {
header("Content-type: image/gif");
imagegif($this->img);
} elseif (function_exists("imagejpeg")) {
header("Content-type: image/jpeg");
imagegif($this->img);
} elseif (imagetypes() & IMG_PNG) {
header("Content-type: image/png");
imagegif($this->img);
} else {
die("No image support in this PHP server");
}

}

//生成验证码字符串
private function createcode() {
$codes = "3456789abcdefghijkmnpqrstuvwxyABCDEFGHIJKLMNPQRSTUVWXY";

$code = "";

for($i=0; $i < $this->num; $i++) {
$code .=$codes{rand(0,strlen($codes)-1)};
}

return $code;
}

//用于自动销毁图像资源
function __destruct() {
imagedestroy($this->img);
}

}