ci验证码类库

由于CI自带的验证码会自动生成文件到本地，这样太占空间

<?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!");
}
}

}

控制器调用：
public function get_code(){
$this->load->library('captcha');
$code = $this->captcha->getCaptcha();
$this->session->set_userdata('code', $code);
$this->captcha->showImg();
}
http://www.ifixedbug.com/posts/codeigniter-captcha-library