CodeIgniter的验证码captcha替代类库

CodeIgniter的验证码captcha使用起来不是特别好用，可以用这个替代类库：

<?php
class Captcha
{
    private $width;
    private $height;
    private $codeNum;
    private $code;
    private $im;
    function __construct($width=80, $height=30, $codeNum=4){
        $this->width = $width;
        $this->height = $height;
        $this->codeNum = $codeNum;
    }
    function showImg(){
        //创建图片
        $this->createImg();
        //设置干扰元素
        $this->setDisturb();
        //设置验证码
        $this->setCaptcha();
        //输出图片
        $this->outputImg();
    }
    function getCaptcha(){ 
  $this->createCode();
        return $this->code;
    }
    private function createImg(){
        $this->im = imagecreatetruecolor($this->width, $this->height);
        $bgColor = imagecolorallocate($this->im, 0, 0, 0);
        imagefill($this->im, 0, 0, $bgColor);
    }
    private function setDisturb(){
        $area = ($this->width * $this->height) / 20;
        $disturbNum = ($area > 250) ? 250 : $area;
        //加入点干扰
        for ($i = 0; $i < $disturbNum; $i++) {
            $color = imagecolorallocate($this->im, rand(0, 255), rand(0, 255), rand(0, 255));
            imagesetpixel($this->im, rand(1, $this->width - 2), rand(1, $this->height - 2), $color);
        }
        //加入弧线
        for ($i = 0; $i <= 5; $i++) {
            $color = imagecolorallocate($this->im, rand(128, 255), rand(125, 255), rand(100, 255));
            imagearc($this->im, rand(0, $this->width), rand(0, $this->height), rand(30, 300), rand(20, 200), 50, 30, $color);
        }
    }
    private function createCode(){
        $str = "23456789abcdefghijkmnpqrstuvwxyzABCDEFGHIJKMNPQRSTUVWXYZ";
        for ($i = 0; $i < $this->codeNum; $i++) {
            $this->code .= $str{rand(0, strlen($str) - 1)};
        }
    }
    private function setCaptcha(){
        for ($i = 0; $i < $this->codeNum; $i++) {
            $color = imagecolorallocate($this->im, rand(50, 250), rand(100, 250), rand(128, 250));
            $size = rand(floor($this->height / 5), floor($this->height / 3));
            $x = floor($this->width / $this->codeNum) * $i + 5;
            $y = rand(0, $this->height - 20);
            imagechar($this->im, $size, $x, $y, $this->code{$i}, $color);
        }
    }
    private function outputImg(){
        if (imagetypes() & IMG_JPG) {
            header('Content-type:image/jpeg');
            imagejpeg($this->im);
        } elseif (imagetypes() & IMG_GIF) {
            header('Content-type: image/gif');
            imagegif($this->im);
        } elseif (imagetype() & IMG_PNG) {
            header('Content-type: image/png');
            imagepng($this->im);
        } else {
            die("Don't support image type!");
        }
    }
}

如何使用？在Account_Controller控制器中加入如下方法：

public function get_code(){
  $this->load->library('captcha');
  $code = $this->captcha->getCaptcha();
  $this->session->set_userdata('code', $code);
  $this->captcha->showImg();
 }

 使用http://www.abc.com/account/get_code/?_=12839400获取验证码图片，在如register方法中检查验证码是否正确：

$code = $this->input->post('code');
$code2 = strtolower($this->session->userdata('code'));
if(strtolower($code) != $code2){
//……
}

OK，就是这样了。