PHP dynamically randomly generates verification code code_PHP tutorial

/************************************************
/ /FILE:ImageCode
//DONE: Generate dynamic verification code class
//DATE"2010-3-31
//Author:www.5dkx.com 5D Happy Blog
**** *************************************************** ********************/
class ImageCode{
private $width; //Verification code image width
private $height; //Height of verification code image
private $codeNum; //Number of verification code characters
private $checkCode; //Verification code characters
private $image; //Verification code canvas
/***************************************************** ************************
// Function: Constructor
// Done: Member attribute initialization
// Author: www.5dkx. com 5D Happy Blog
************************************************ *****************************/
function __construct($width=60,$height=20,$codeNum=4)
{
$this->width = $width;
$this->height = $height;
$this->codeNum = $codeNum;
$this->checkCode = $this->createCheckCode();
}
function showImage()
{
$this->getcreateImage();
$this->outputText();
$this->setDisturbColor();
$this- >outputImage();
}
function getCheckCode()
{
return $this->chekCode;
}
private function getCreateImage()
{
$this->image = imagecreatetruecolor($this->width,$this->height);
$back = imagecolorallocate($this->image,255,255,255);
$border = imagecolorallocate ($this->image,255,255,255);
imagefilledrectangle($this->image,0,0,$this->width-1,$this->height-1,$border);
//Use pure white to fill the rectangular frame. If used here, the subsequent interference code will be invalid
/*If you want to use interference code, use the following*/
//imagerectangle($this->image,0, 0,$this->width-1,$this->height-1,$border);
}
private function createCheckCode()
{
for($i=0; $i<$this->codeNum;$i++)
{
$number = rand(0,2);
switch($number)
{
case 0: $rand_number = rand(48,57); break;//Numbers
case 1: $rand_number = rand(65,90);break;//Capital letters
case 2: $rand_number = rand(97,122);break ;//Lowercase letters
}
$asc = sprintf("%c",$rand_number);
$asc_number = $asc_number.$asc;
}
return $asc_number;
}
private function setDisturbColor()//Interference setting
{
for($i=0;$i<=100;$i++)
{
//$color = imagecolorallocate($this->image,rand(0,255),rand(0,255),rand(0,255));
$color = imagecolorallocate($this->image,255,255,255);
imagesetpixel($ this->image,rand(1,$this->width-2),rand(1,$this->height-2),$color);
}
//$color = imagecolorallocate($this->image,0,0,0);
//imagesetpixel($this->image,rand(1,$this->width-2),rand(1,$this ->height-2),$color);
}
private function outputText()
{
//Random color, random placement, random string output to image
for ($i=0;$i<=$this->codeNum;$i++)
{
$bg_color = imagecolorallocate($this->image,rand(0,255),rand(0,128),rand (0,255));
$x = floor($this->width/$this->codeNum)*$i+3;
$y = rand(0,$this->height- 15);
imagechar($this->image,5,$x,$y,$this->checkCode[$i],$bg_color);
}
}
private function outputImage()
{
if(imagetypes()&IMG_GIF)
{
header("Content_type:image/gif");
imagegif($this->image);
}
elseif(imagetypes()&IMG_JPG)
{
header("Content-type:image/jpeg");
imagejpeg($this->image,"",0.5) ;
}
elseif(imagetypes()&IMG_PNG)
{
header("Content-type:image/png");
imagejpeg($this->image);
}
elseif(imagetypes()&IMG_WBMP)
{
header("Content-type:image/vnd.wap.wbmp");
imagejpeg($this->image);
}
else
{
die("PHP does not support image creation");
}
}
function __destruct()
{
imagedestroy($ this->image);
}
}
/*display*/
/*******************************************************************
session_start();
$image = new ImageCode(60,20,4);
$image->showImage();
$_SESSION['ImageCode'] = $image->getCheckCode();
*******************************************************************/
?>