PHP实现适用于自定义的验证码类

<?php
 
/* 
 * to change this license header, choose license headers in project properties.
 * to change this template file, choose tools | templates
 * and open the template in the editor.
 */
class image{
  
 private $img;
 public $width = 85;
 public $height = 25;
 public $code;
 public $code_len = 4;
 public $code_str = "329832983dsdskdslkqwewq2lkfdsfsdjfdsfdsjwlkfj93290kfdskjfdsoidslk";
 public $bg_color = '#dcdcdc';
 public $font_size = 16;
 public $font = 'font.ttf';
 public $font_color = '#000000';
  
 //创建验证码饿字符创
 public function create_code(){
  $code = '';
  for( $i=0;$i<$this->code_len;$i++ ){
   $code .= $this->code_str[mt_rand(0, strlen($this->code_str)-1)];
 }
  return $this->code = $code;
 }
  
 //输出图像
 public function getimage(){
  $w = $this->width;
  $h = $this->height;
  $bg_color = $this->bg_color;
  $img = imagecreatetruecolor($w, $h);
  $bg_color = imagecolorallocate($img, 
 hexdec(substr($bg_color, 1,2)), hexdec(substr($bg_color, 3,2)), hexdec(substr($bg_color, 5,2)));
 imagefill($img, 0, 0, $bg_color);
  $this->img = $img;
  $this->create_font();
  $this->create_pix();
 $this->show_code();
 }
 
 
 //写入验证码
 public function create_font(){
  $this->create_code();
  $color = $this->font_color;
  $font_color = imagecolorallocate($this->img, hexdec(substr($color,1,2)), hexdec(substr($color, 3,2)), hexdec(substr($color,5,2)));
  $x = $this->width/$this->code_len;
  for( $i=0;$i<$this->code_len;$i++ ){
   $txt_color = imagecolorallocate($this->img, mt_rand(0,100), mt_rand(0, 150), mt_rand(0, 200));
   imagettftext($this->img, $this->font_size, mt_rand(-30, 30), $x*$i+mt_rand(3, 6), mt_rand($this->height/1.2, $this->height), $txt_color, $this->font , $this->code[$i]); 
   //imagestring($this->img, $this->font_size, $x*$i+mt_rand(3, 6),mt_rand(0, $this->height/4) , $this->code[$i], $font_color);
  }
  $this->font_color = $font_color;
 }
  
 //画干扰线
 public function create_pix(){
  $pix_color= $this->font_color;
  for($i=0;$i<100;$i++){
   imagesetpixel($this->img, mt_rand(0, $this->width),mt_rand(0, $this->height), $pix_color);
  }
  for($j=0;$j<4;$j++){
   imagesetthickness($this->img, mt_rand(1, 2));
   imageline($this->img, mt_rand(0, $this->width), mt_rand(0, $this->height), mt_rand(0, $this->width), mt_rand(0, $this->height), $pix_color);
  }
 }
  
 //得到验证码
 public function getcode(){
  return strtoupper($this->code);
 }
 
 
 //输出验证码
 private function show_code(){
  header("content-type:image/png");
  imagepng($this->img);
  imagedestroy($this->img);
 }
}