How to build beautiful PHP Verification code class file and call method

Captcha class Validatecode {private $charset = ' abcdefghkmnprstuvwxyzABCDEFGHKMNPRSTUVWXYZ23456789 ';//random factor private $ code;//Verification Code Private $codelen = 4;//captcha length Private $width = 130;//width Private $height = 50;//height private $img;//graphics resource handle private $font;//The specified font private $fontsize = 20;//Specifies the font size of private $fontcolor;//Specifies the font color//constructor method to initialize public function __construct () {$this ->font = DirName (__file__). '  /font/elephant.ttf ';//Note the font path to write to, otherwise not show the picture}//Generate random Code Private Function Createcode () {$_len = strlen ($this->charset)-1;  for ($i =0; $i < $this->codelen; $i + +) {$this->code. = $this->charset[mt_rand (0,$_len)];  }}//Generate background Private function createbg () {$this->img = Imagecreatetruecolor ($this->width, $this->height);  $color = Imagecolorallocate ($this->img, Mt_rand (157,255), Mt_rand (157,255), Mt_rand (157,255)); Imagefilledrectangle ($this->img,0, $this->height, $this->width,0, $color);  }//Generate text Private function CreateFont () {$_x = $this->width/$this->codelen; For ($I=0, $i < $this->codelen; $i + +) {$this->fontcolor = imagecolorallocate ($this->img,mt_rand (0,156), Mt_rand (   0,156), Mt_rand (0,156)); Imagettftext ($this->img, $this->fontsize,mt_rand ( -30,30), $_x* $i +mt_rand (1,5), $this->height/1.4, $this-  >fontcolor, $this->font, $this->code[$i]); }}//Generate line, snowflake Private Function Createline () {//Line for ($i =0; $i <6; $i + +) {$color = Imagecolorallocate ($this->img   , Mt_rand (0,156), Mt_rand (0,156), Mt_rand (0,156)); Imageline ($this->img,mt_rand (0, $this->width), Mt_rand (0, $this->height), Mt_rand (0, $this->width), Mt_  Rand (0, $this->height), $color); }//Snowflake for ($i =0; $i <100; $i + +) {$color = Imagecolorallocate ($this->img,mt_rand (200,255), Mt_rand (200,255), Mt_ran   D (200,255));  Imagestring ($this->img,mt_rand (1,5), Mt_rand (0, $this->width), Mt_rand (0, $this->height), ' * ', $color);  }}//output private function output () {header (' content-type:image/png ');  Imagepng ($this->img); Imagedestroy ($this->img); }//External generation Public Function doimg () {$this->createbg ();  $this->createcode ();  $this->createline ();  $this->createfont (); $this->output (); }//Get Verification Code Public Function GetCode () {return strtolower ($this->code);}}

How to use:
1, first save the verification code class as a file named ValidateCode.class.php;
2. Create a new file named captcha.php to call the class;
captcha.php

3, refer to the page, the code is as follows:

4, a complete verification page, the code is as follows:

<?phpsession_start ();    On the page first to open session,//error_reporting (2047);    Session_destroy ();    Remove the session to get a new session value each time; With seesion effect is good, also very convenient? >