phpGD库函数之验证码类

<?php
class Captcha
{
  //字体文件
  private $_fontfile = '';
  //字体大小
  private $_size = 20;
  //画布宽度
  private $_width = 120;
  //画布高度
  private $_height = 40;
  //验证码长度
  private $_length = 4;
  //画布资源
  private $_image = null;
  //干扰元素
  //雪花的个数 *
  private $_snow = 0;
  //像素个数
  private $_pixel = 50;
  //线段个数
  private $_line = 3;
  /**
   * 初始化数据
   * @param array $config
   */
  public function __construct($config = array())
  {
    if (is_array($config) && count($config) > 0) {
      //检测字体文件是否存在并且可读
      if (isset($config['fontfile']) && is_file($config['fontfile']) && is_readable($config['fontfile'])) {
        $this->_fontfile = $config['fontfile'];
      } else {
        return false;
      }
      //检测是否设置字体大小
      if (isset($config['size']) && $config['size'] > 0) {
        $this->_size = (int)$config['size'];
      }
      //检测是否设置画布宽度
      if (isset($config['width']) && $config['width'] > 0) {
        $this->_width = (int)$config['width'];
      }
      //检测是否设置画布高度
      if (isset($config['height']) && $config['height'] > 0) {
        $this->_height = (int)$config['height'];
      }
      //检测是否设置验证码长度
      if (isset($config['length']) && $config['length'] > 0) {
        $this->_length = (int)$config['length'];
      }
      //配置干扰元素
      if (isset($config['snow']) && $config['snow'] > 0) {
        $this->_snow = $config['snow'];
      }
      if (isset($config['pixel']) && $config['pixel'] > 0) {
        $this->_pixel = $config['pixel'];
      }
      if (isset($config['line']) && $config['line'] > 0) {
        $this->_line = $config['line'];
      }
      $this->_image = imagecreatetruecolor($this->_width, $this->_height);
      return $this->_image;
    } else {
      return false;
    }
  }

  /**
   * 得到验证码
   *
   * @return void
   */
  public function getCaptcha()
  {
    $white = imagecolorallocate($this->_image, 255, 255, 255);
    //填充矩形
    imagefilledrectangle($this->_image, 0, 0, $this->_width, $this->_height, $white);
    //生成验证码
    $str = $this->_generateStr($this->_length);
    if (false === $str) {
      return false;
    }
    $fontfile = $this->_fontfile;
    //绘制验证码
    for ($i = 0; $i < $this->_length; $i++) {
      $size = $this->_size;
      $angle = mt_rand(-30, 30);
      $x = ceil($this->_width / $this->_length) * $i + mt_rand(5, 10);
      $y = ceil($this->_height / 1.5);
      $color = $this->_getRandColor();
      $text = mb_substr($str, $i, 1, 'utf-8');
      imagettftext($this->_image, $size, $angle, $x, $y, $color, $fontfile, $text);
    }
    //* -- 像素和线段
    if ($this->_snow) {
      $this->_getSnow();
    } else {
      if ($this->_pixel) {
        $this->_getPixel();
      }
      if ($this->_line) {
        $this->_getLine();
      }
    }
    //输出图像
    header('content-type:image/png');
    imagepng($this->_image);
    imagedestroy($this->_image);
    return strtolower($str);
  }

  /**
   * 产生雪花
   *
   * @return void
   */
  private function _getSnow()
  {
    for ($i = 1; $i <= $this->_snow; $i++) {
      imagestring($this->_image, mt_rand(1, 5), mt_rand(0, $this->_width), mt_rand(0, $this->_height), "*", $this->_getRandColor());
    }
  }
  /**
   * 绘制像素
   *
   * @return void
   */
  private function _getPixel()
  {
    for ($i = 1; $i <= $this->_pixel; $i++) {
      imagesetpixel($this->_image, mt_rand(0, $this->_width), mt_rand(0, $this->_height), $this->_getRandColor());
    }
  }
  /**
   * 绘制线段
   *
   * @return void
   */
  private function _getLine()
  {
    for ($i = 1; $i <= $this->_line; $i++) {
      imageline($this->_image, mt_rand(0, $this->_width), mt_rand(0, $this->_height), mt_rand(0, $this->_width), mt_rand(0, $this->_height), $this->_getRandColor());
    }
  }
  /**
   * 产生验证码字符
   *
   * @param integer $length  验证码长度
   * @return void   $string  随机字符
   */
  private function _generateStr($length)
  {
    if ($length < 1 || $length > 30) {
      return false;
    }
    $chars = array(
      'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'k', 'm', 'n', 'p', 'x', 'y', 'z',
      'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'K', 'M', 'N', 'P', 'X', 'Y', 'Z',
      1, 2, 3, 4, 5, 6, 7, 8, 9
    );
    $str = join("", array_rand(array_flip($chars), $length));
    return $str;
  }
  private function _getRandColor()
  {
    return imagecolorallocate($this->_image, mt_rand(0, 255), mt_rand(0, 255), mt_rand(0, 255));
  }
}