<?php
class Captcha
{

 private $charset = 'abcdefghkmnprstuvwxyzABCDEFGHKMNPRSTUVWXYZ23456789'; //随机因子 
 private $code = ""; //验证码 
 private $codelen = 4; //验证码长度 
 private $width = 120; //宽度 
 private $height = 36; //高度 
 private $img; //图形资源句柄 
 private $font; //指定的字体 
 private $fontsize = 20; //指定字体大小 
 private $fontcolor; //指定字体颜色 

 //构造方法初始化 

 public function __construct()
 {
 $this->font = dirname(__FILE__) . '/font.ttf'; //注意字体路径要写对,否则显示不了图片 
 }
 
 //生成随机码 
 private function createCode()
 {
 $this->code = "";
 $_len = strlen($this->charset) - 1;
 for ($i = 0; $i < $this->codelen; $i++) {
 $this->code .= $this->charset[mt_rand(0, $_len)];
 }
 }

 //生成背景 
 private function createBg()
 {
 $this->img = imagecreatetruecolor($this->width, $this->height);
 $color = imagecolorallocate($this->img, mt_rand(157, 255), mt_rand(157, 255), mt_rand(157, 255));
 imagefilledrectangle($this->img, 0, $this->height, $this->width, 0, $color);
 }

 //生成文字 
 private function createFont()
 {
 $_x = $this->width / $this->codelen;
 $code = $this->code == "" ? $this->getCode() : $this->code;
 for ($i = 0; $i < $this->codelen; $i++) {
 $this->fontcolor = imagecolorallocate($this->img, mt_rand(0, 156), mt_rand(0, 156), mt_rand(0, 156));
 imagettftext($this->img, $this->fontsize, mt_rand(-30, 30), $_x * $i + mt_rand(1, 5), $this->height / 1.4, $this->fontcolor, $this->font, $code[$i]);
 }
 }

 //生成线条、雪花 
 private function createLine()
 {
 //线条 
 for ($i = 0; $i < 6; $i++) {
 $color = imagecolorallocate($this->img, mt_rand(0, 156), mt_rand(0, 156), mt_rand(0, 156));
 imageline($this->img, mt_rand(0, $this->width), mt_rand(0, $this->height), mt_rand(0, $this->width), mt_rand(0, $this->height), $color);
 }
 //雪花 
 for ($i = 0; $i < 100; $i++) {
 $color = imagecolorallocate($this->img, mt_rand(200, 255), mt_rand(200, 255), mt_rand(200, 255));
 imagestring($this->img, mt_rand(1, 5), mt_rand(0, $this->width), mt_rand(0, $this->height), '*', $color);
 }
 }

 //输出 
 private function outPut()
 {
 $this->response->header('Content-type', "image/png");
 imagepng($this->img);
 imagedestroy($this->img);
 }

 //对外生成 
 public function create($width = null, $height = null)
 {
 $width != null && $this->width = $width;
 $height != null && $this->height = $height;
 $this->createBg();
 $this->createLine();
 $this->createFont();
 $this->outPut();
 }

 //获取验证码 
 public function getCode()
 {
 $this->createCode();
 return strtolower($this->code);
 }

 
 //生成base64图片 
 public function img($code, $htmlColor = "#000")
 {
 $code != null && $this->code = $code;
 $this->fontsize = 14;
 $this->width = strlen($code) * $this->fontsize;
 $this->height = $this->fontsize + 2;

 $hex = str_replace("#", "", $htmlColor);
 if(strlen($hex) == 3) {
 $r = hexdec(substr($hex,0,1).substr($hex,0,1));
 $g = hexdec(substr($hex,1,1).substr($hex,1,1));
 $b = hexdec(substr($hex,2,1).substr($hex,2,1));
 } else {
 $r = hexdec(substr($hex,0,2));
 $g = hexdec(substr($hex,2,2));
 $b = hexdec(substr($hex,4,2));
 }
 $this->img = imagecreatetruecolor($this->width, $this->height);
 $color = imagecolorallocate($this->img, 255, 255, 255);
 imagefilledrectangle($this->img, 0, $this->height, $this->width, 0, $color);
 $this->fontcolor = imagecolorallocate($this->img, $r, $g, $b);
 imagestring($this->img,$this->fontsize,0, 0,$this->code,$this->fontcolor); 
 ob_start();
 imagepng($this->img);
 $image_data = ob_get_contents();
 ob_end_clean();
 $base64_image = 'data:png;base64,' . chunk_split(base64_encode($image_data));
 return $base64_image;
 }
 
}