PHP之验证码

<?php

    header("content-type:image/jpeg");
    //验证码函数
    function getVerify($type = 4){

        //字码表
        $chars = "1234567890qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM";
        //字符串的长度
        $len = strlen($chars);
        //预定义code
        $verify = '';

        //产生四位随机数 ，从字码表当中
        for ($i=1; $i <= $type ; $i++) { 
            $one_index = mt_rand(0 ,$len-1);

            $verify.= $chars[$one_index];
        }

        //创建画布
        $width = 500;
        $height = 300;

        $image = imagecreatetruecolor($width, $height);

        //配色
        $color = "";

        //随机颜色
        $color = imagecolorallocate($image,210,105,30); 
        
        
        //填充
        imagefill($image, 0, 0, $color);
        
        

        $font = 5;
        //获得图像的宽高
        $img_w = imagesx($image);
        $img_h = imagesy($image);

        //获得字体的宽高
        $font_w = imagefontwidth($font);
        $font_h = imagefontheight($font);

        //获得字符串的宽高
        $str_w = $font_w*$type;
        $str_h = $font_h;

        //居中显示
        $x = ($img_w - $str_w)/2;
        $y = ($img_h - $str_h)/2;
        $color = imagecolorallocate($image, 128,0,0);
        imagestring($image, $font, $x, $y, $verify, $color);

        //输出
        imagejpeg($image);

        //销毁画像资源
        imagedestroy($image);
    }

    getVerify(10);