php利用GD库生成缩略图。

复制代码 代码如下:

<form method="post" action="suo_do.php" enctype="multipart/form-data">

<input type="file" name="pic" />

<input type="submit" value="上传1" />

</form>

<?php

header("content-type:text/html;charset=gbk");

ini_set("date.timezone","Asia/chong");

//判断文件是否为空

if(empty($_FILES)){

echo"上传文件过大";

exit;

}

//判断文件上传是否有错误

if($_FILES['pic']['error']){

echo "上传文件";

exit;

}

//判断文件类型是否非法获取文件后缀

$allowtype=array("jpg","png","jpeg","gif");

$a=explode('.',$_FILES['pic']['name']);

$index=count($a)-1;

$ex=strtolower($a[$index]);

if(!in_array($ex,$allowtype)){

echo "上传文件非法";

exit;

}

$file=date('YmdHis').rand().".".$ex;

$src=$_FILES['pic']['tmp_name'];

$des="upload/".$file;

$rs=move_uploaded_file($src,$des);

//缩略图

//读取已经上传图片

$image=imagecreatefromjpeg($des);

$a=getimagesize($des);

$w=$a[0];

$h=$a[1];

if($w>$h){

$width=300;

$height=$width/$w*$h;

}else if($w<$h){

$height=300;

$width=$height/$h*$w;

}else{

$width=300;

$height=300;

}

//创建空白新图片

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

//copy源图片内容 copy新图片

imagecopyresized($newimage, $image, 0,0, 0,0, $width, $height, $w, $h);

$filename="upload/s_".$file;

imagejpeg($newimage,$filename);