php下生成验证码的类

<?php
session_start();

$imgWidth = isset($_REQUEST["width"]) ? intval($_REQUEST["width"]) : 0;
$imgHeight = isset($_REQUEST["height"]) ? intval($_REQUEST["height"]) : 0;
$length = isset($_REQUEST["length"]) ? intval($_REQUEST["length"]) : 0;
$captcha = new VerifyCode(array('width'=>$imgWidth,'height'=>$imgHeight,'length'=>$length));
$captcha->CreateImage();


class VerifyCode {
    public $width  = 140;
    public $height = 60;
    public $glbVerifySeed = "123456789abcdefghigklnmpqrstuvxyz";
    public $strLength = 6;
    public $session_var = 'verifyCode';
    public $backgroundColor = array(255, 255, 255);
    public $colors = array(
        array(27,78,181), // blue
        array(22,163,35), // green
        array(214,36,7),  // red
        array(0,0,0),  // black
    );
    public $PolluteNum = 100;
    public $Yperiod    = 10;
    public $Yamplitude = 8;
    public $Xperiod    = 8;
    public $Xamplitude = 4;


    public $maxRotation = 8;
    public $scale = 2;


    public $imageFormat = 'png';
    public $im;


    public function __construct($config = array()) {
        if(intval($config['width'])>50) $this->width = $config['width'];
        if(intval($config['height'])>20) $this->height = $config['height'];
        if(intval($config['length'])>2) $this->strLength = $config['length'];
        if($this->width>150 || $this->height>50) {
            $this->scale = 1;
        }
        $this->PolluteNum = intval($this->width*$this->height/40);
    }


    // 创建图片
    public function CreateImage() {
        $ini = microtime(true);
        $this->ImageAllocate();
        $text = $this->GetCaptchaText();
$_SESSION[$this->session_var] = $text;


        $this->WriteText($text);// 写入内容

        if($this->height>30) {
            $this->WaveImage();	// 图片变形
        }
//$this->Pollute();	 // 画出杂点
$this->Line();	 // 画出一条线
        $this->ReduceImage();	// 缩放图片
        
        $this->WriteImage();	// 输出图片
        $this->Cleanup();
    }


    // 初始图片参数
    protected function ImageAllocate() {
        if (!empty($this->im)) {
            imagedestroy($this->im);
        }


        $this->im = imagecreatetruecolor($this->width*$this->scale, $this->height*$this->scale);


        $this->GdBgColor = imagecolorallocate($this->im,
            $this->backgroundColor[0],
            $this->backgroundColor[1],
            $this->backgroundColor[2]
        );
        imagefilledrectangle($this->im, 0, 0, $this->width*$this->scale, $this->height*$this->scale, $this->GdBgColor);


        $color           = $this->colors[mt_rand(0, sizeof($this->colors)-1)];
        $this->GdFgColor = imagecolorallocate($this->im, $color[0], $color[1], $color[2]);
    }


    // 获取生成的字母
    protected function GetCaptchaText() {
        $bgnIdx = 0;
        $endIdx = strlen($this->glbVerifySeed)-1;
        $code = "";
        for($i=0; $i<$this->strLength; $i++) {
            $curPos = rand($bgnIdx, $endIdx);
            $code .= substr($this->glbVerifySeed, $curPos, 1);
        }
        return $code;
    }


    // 写入字母
    protected function WriteText($text) {
        $fontcfg = array(
            'spacing' => 0, 
            'minSize' => $this->height/2+2, 
            'maxSize' => $this->height/2+4, 
            'font' => 'Duality.ttf'
        );


        $x      = 10*$this->scale;
        $y      = round(($this->height*27/40)*$this->scale);
        $length = strlen($text);
        for ($i=0; $i<$length; $i++) {
            $degree   = rand($this->maxRotation*-1, $this->maxRotation);
            $fontsize = rand($fontcfg['minSize'], $fontcfg['maxSize'])*$this->scale;
            $letter   = substr($text, $i, 1);
            
            $coords = imagettftext($this->im, $fontsize, $degree,
                $x, $y,
                $this->GdFgColor, $fontcfg['font'], $letter);
            $x += ($coords[2]-$x) + ($fontcfg['spacing']*$this->scale);
        }
    }


    // 图片变形
    protected function WaveImage() {
        $xp = $this->scale*$this->Xperiod*rand(1,3);
        $k = rand(0, 100);
        for ($i = 0; $i < ($this->width*$this->scale); $i++) {
            imagecopy($this->im, $this->im,
                $i-1, sin($k+$i/$xp) * ($this->scale*$this->Xamplitude),
                $i, 0, 1, $this->height*$this->scale);
        }


        $k = rand(0, 100);
        $yp = $this->scale*$this->Yperiod*rand(1,2);
        for ($i = 0; $i < ($this->height*$this->scale); $i++) {
            imagecopy($this->im, $this->im,
                sin($k+$i/$yp) * ($this->scale*$this->Yamplitude), $i-1,
                0, $i, $this->width*$this->scale, 1);
        }
    }


    // 缩小图片
    protected function ReduceImage() {
        $imResampled = imagecreatetruecolor($this->width, $this->height);
        imagecopyresampled($imResampled, $this->im,
            0, 0, 0, 0,
            $this->width, $this->height,
            $this->width*$this->scale, $this->height*$this->scale
        );
        imagedestroy($this->im);
        $this->im = $imResampled;
    }


    // 输出图片
    protected function WriteImage() {
        if ($this->imageFormat == 'png' && function_exists('imagepng')) {
            header("Content-type: image/png");
            imagepng($this->im);
        } else {
            header("Content-type: image/jpeg");
            imagejpeg($this->im, null, 80);
        }
    }


    // 画出杂点
    protected function Pollute() {
        $imgWidth = imagesx($this->im);
        $imgHeight = imagesy($this->im);
        for($j=0; $j<$this->PolluteNum; $j++) {
            $x = rand(0, $imgWidth);
            $y = rand(0, $imgHeight);
            imagesetpixel($this->im, $x, $y, $this->GdFgColor);
        }
    }


// 画出一条线
protected function Line() {
$imgWidth = imagesx($this->im);
$imgHeight = imagesy($this->im);
$y = ceil($imgHeight/2);
$border = floor($imgHeight/20);
for($j=10; $j<($imgWidth-10); $j++) {
$x = $j;
$y = rand(-1,1)+$y;
for($i=0; $i<$border; $i++) {
imagesetpixel($this->im, $x, $y+$i, $this->GdFgColor);
}
}
}


    protected function Cleanup() {
        imagedestroy($this->im);
    }
}
?>