php利用GD庫生成縮略圖示例

php利用GD庫生成縮略圖。
復制代碼 代碼如下:
<form method="post" action="suo_do.php" enctype="multipart/form-data">
<input type="file" name="pic" />
<input type="submit" value="上傳1" />
</form>
<?php
header("content-type:text/html;charset=gbk");
ini_set("date.timezone","Asia/chong");
//判斷文件是否為空
if(empty($_FILES)){
echo"上傳文件過大";
exit;
}
//判斷文件上傳是否有錯誤
if($_FILES['pic']['error']){
echo "上傳文件";
exit;
}
//判斷文件類型是否非法獲取文件後綴
$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 "上傳文件非法";
exit;
}
$file=date('YmdHis').rand().".".$ex;
$src=$_FILES['pic']['tmp_name'];
$des="upload/".$file;
$rs=move_uploaded_file($src,$des);


//縮略圖
//讀取已經上傳圖片
$image=imagecreatefromjpeg($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;
}
//創建空白新圖片
$newimage=imagecreatetruecolor($width, $height);
//copy源圖片內容 copy新圖片
imagecopyresized($newimage, $image, 0,0, 0,0, $width, $height, $w, $h);
$filename="upload/s_".$file;
imagejpeg($newimage,$filename);