<?php
/**
?*?生成驗證碼
?*?@param?integer?$type?類型0：純數字?類型1：字母?類型2：數字+字母
?*?@param?integer?$length?驗證碼長度
?*?@param?integer?$width?畫布寬度
?*?@param?integer?$height?畫布高度
?*?@return?string?驗證碼字符串
?*/
function?generateVerify($type=2,?$length=4,?$width=100,?$height=30)?{
????//?新建一個真彩色圖像
????$image?=?imagecreatetruecolor($width,?$height);
????//?為一副圖像分配顏色
????$white?=?imagecolorallocate($image,?255,?255,?255);
????//?畫一矩形并填充
????imagefilledrectangle($image,?0,?0,?$width,?$height,?$white);

????function?randColor($image)?{
????????return?imagecolorallocate($image,?mt_rand(0,?255),?mt_rand(0,?255),?mt_rand(0,?255));
????}

????switch($type)?{
????????//?產生隨機數字
????????case?0:
????????????$str?=?join('',?array_rand(range(0,9),?$length));
????????????break;
????????//?產生隨機字母
????????case?1:
????????????$str?=?join('',?array_rand(array_flip(array_merge(range('a',?'z'),?range('A',?'Z'))),?$length));
????????????break;
????????//?產生隨機數字字母
????????case?2:
????????????$str?=?join('',?array_rand(array_flip(array_merge(range(0,?9),?range('a',?'z'),?range('A',?'Z'))),?$length));
????????????break;
????}

????//??用?TrueType?字體向圖像寫入文本
????for($i=0;$i<$length;$i++)?{
????????imagettftext($image,?16,?mt_rand(-30,?30),?$i*($width/$length),?mt_rand($height-15,?25),?randColor($image),?'.\font\Microsoft-YaHei-Light.ttc',?$str[$i]);
????}

????//?生成像素點
????for?($i=1;$i<=100;$i++)?{
????????imagesetpixel($image,?mt_rand(0,?$width),?mt_rand(0,?$height),?randColor($image));
????}

????//輸出圖像
????header('Content-type:image/png');
????imagepng($image);
????imagedestroy($image);

????return?$str;
}
generateVerify();