请各位帮我看看怎么回事,图片显示是破裂的
<?php
require_once 'string.func.php';
//通过GD库做验证码
//创建画布
session_start();
$width=80;
$height=28;
// 新建一个真彩色图像
$image=imagecreatetruecolor($width,$height);
//为一幅图像分配颜色
$white=imagecolorallocate($image,255,255, 255);
//为一幅图像分配颜色
$black=imagecolorallocate($image, 0, 0,0);
//画一矩形并填充
imagefilledrectangle($image, 1, 1, $width-2, $height-2, $black);
$type=1;
$length=4;
$chars=buildRandomString($type,$length);
$sess_name="verify";
$_SESSION[$sess_name]=$chars;
$fontfiles=array('MSYH.TTF');
for($i=0;$i<$length;$i++){
$size=mt_rand(14,18);
$angle=mt_rand(-15,15);
$x=5+$i*$size;
$y=mt_rand(20,26);
$fontfile="../fonts".$fontfiles[mt_rand(0,count($fontfiles)-1)];
$text=substr($chars,$i,1);
// 用 TrueType 字体向图像写入文本
imagettftext($image, $size, $angle, $x, $y, $color, $fontfile, $text);
}
header("content-type:image/gif");
imagegif($image);
imagedestroy($image);
<?php
function buildRandomString($type=1,$length=4){
if($type==1){
$chars=join("",range(0,9));
}
elseif($type==2){
$chars=join("",array_merge(range("a","z"),range("A","Z")));
}
elseif($type==3){
$chars=join("",array_merge(range("a","z"),range("A","Z"),range(0,9)));
}
if($length>strlen($chars)){
exit("字符串长度不够");
}
$chars=str_shuffle($chars);
return substr($chars,0,$length);
}