A question about the GP library in PHP

Ask for a question about the GP library inside PHP
The GD library is encapsulated into the class, but I don't know where it went wrong,
Please take a look at the time, the younger brother is grateful, thank you
Looking for two days did not find there is wrong, the picture is still not show,
Such as:

(I wrote a form biaodan.php first)



<title>Codetest</title>









(then encapsulates a class vcode.class.php)
Class vcode{
Private $width; Wide
private $height;//High
Private $num; Number
private $code;//Verification Code
Private $img; Resources for images

Construction method, three parameters
function __construct ($width, $height, $num) {
$this->width= $width;
$this->height= $height;
$this->num= $num;
$this->code= $this->gocode ();//Call your own method
}

Gets the verification code for the character to be saved in the server
function GetCode () {

return $this->code;


}
Output image
function outimg () {
Create background (color, size, border)
$this->createback ();

Output image
$this->printimg ();
}
Create a background
Private Function Createback () {
Create a resource
$this->img=imagecreatetruecolor ($this->width, $htis->height);
Set Random Colors
$bgcolor =imagecolorallocate ($this->img,rand (225,255), Rand (225,255), Rand (225,255));
Set Background fill
Imagefill ($this->img,0,0, $bgcolor);
Draw Border
$bordercolor =imagecolorallocate ($this->img,0,0,0);
Imagerectangle ($this->img,0,0, $this->width-1, $this->height-1, $bordercolor);
}

Stooped
Private Function outstring () {


}

Setting interference elements
Private Function Grcode () {

}

Output image
Private Function printimg () {
if (Imagetypes () & Img_gif) {
Header ("Content-type:image/gif");
Imagegif ($this->img);
}else if (Imagetypes () & img_jpg) {
Header ("Content-type:image/jpeg");
Imagejpeg ($this->img);
}else if (Imagetypes () & Img_png) {
Header ("Content-type:image/png");
Imagepng ($this->img);
}else{
Die ("No image, support in this PHP server");
}
}

Generate Authenticode String
Private Function Gocode () {
$codes = "3456789abcdefghijkmnpqrstuvwxyABCDEFGHIJKLMNPQRSTUVWXY";
$code = "";
for ($i =0; $i < $this->num; $i +) {
$code. = $codes {rand (0,strlen ($codes)-1)};
}
return $code;
}

For automatic destruction of image resources
function __destruct () {
Imagedestroy ($this->img);
}

}


(In call class code.php)
Open session
Session_Start ();
Include "vcode.class.php";
Construction method
$vcode = new Vcode (80,25,4);
Save a copy of the validation to the server's own space
$_session= $vcode->getcode ();
The Captcha picture output
$vcode->outimg ();
------to solve the idea----------------------
Create a resource
$this->img=imagecreatetruecolor ($this->width,$ Htis->height);

