啥也不说，直接上代码，大家可以自行添加增加水印功能：
<?php
/**
*
* @author zhao jinhan
* @date 2014年1月13日11:54:30
* @email [email protected]
*
*/
header('Content-type:text/html; charset=utf-8');
//定义缩略图的宽高
define('THUMB_WIDTH',300);
define('THUMB_HEIGHT',300);
/**
* 重新生成上传的文件名
* @return string
* @author zhao jinhan
*
*/
function _file_type($filetype = null){
switch($filetype)
{
case "image/jpeg":
$fileextname = "jpg";
break;
case "image/gif":
$fileextname = "gif";
break;
case "image/png":
$fileextname = "png";
break;
default:
$fileextname = false;
break;
}
return $fileextname?date('YmdHis',time()).'.'.$fileextname:false;
}
/**
*
* @param string $filename
* @param string $width
* @param string $height
* @param string $quality
* @param string $savepath
* @return boolean
*/
function _make_thumb($filename='', $width=THUMB_WIDTH, $height=THUMB_HEIGHT, $savepath='./upload'){
if(file_exists($filename)){
//上传图片的尺寸
$imagesize=getimagesize($filename);
$imagewidth=$imagesize[0];
$imageheight=$imagesize[1];
$mime = $imagesize['mime'];
//宽高比例
$ratio = $imagewidth/$imageheight;
//新建一个背景图片
$bgimg = imagecreatetruecolor($width, $height);
$white = imagecolorallocate($bgimg, 255, 255, 255);
//填充背景色为白色
imagefill($bgimg,0,0,$white);
if($mime == 'image/gif'){
$im = @imagecreatefromgif($filename); /* Attempt to open */
$outfun = 'imagegif';
}elseif($mime == 'image/png'){
$im = @imagecreatefrompng($filename); /* Attempt to open */
$outfun = 'imagepng';
}else{
$im = @imagecreatefromjpeg($filename); /* Attempt to open */
$outfun = 'imagejpeg';
}
if($ratio > 1){
//宽度较大
if($imagewidth > $width){
//缩放图片到背景图片上
$new_width = $width;
$new_height = ($width*$imageheight)/$imagewidth;
$bg_y = ceil(abs(($height-$new_height)/2));
imagecopyresampled($bgimg, $im, 0, $bg_y, 0, 0, $new_width, $new_height, $imagewidth, $imageheight);
}else{
//复制图片到背景图片上
$copy = true;
}
}else{
//高度较大
if($imageheight > $height){
//缩放图片
$new_height = $height;
$new_width = ($height*$imagewidth)/$imageheight;
$bg_x = ceil(($width-$new_width)/2);
imagecopyresampled($bgimg, $im, $bg_x, 0, 0, 0, $new_width, $new_height, $imagewidth, $imageheight);
}else{
//复制图片到背景图片上
$copy = true;
}
}
if($copy){
//复制图片到背景图片上
$bg_x = ceil(($width-$imagewidth)/2);
$bg_y = ceil(($height-$imageheight)/2);
imagecopy($bgimg, $im, $bg_x, $bg_y, 0, 0, $imagewidth, $imageheight);
}
$ext = _file_type($mime);
$outfun($bgimg, $savepath.'/'.$ext);
imagedestroy($bgimg);
return $savepath.'/'.$ext;
}else{
return false;
}
}
if($_POST){
$size = $_POST['size']?strtoupper(trim($_POST['size'])):'2M';
$imgsize = $_FILES['img']['size']?$_FILES['img']['size']/(1024*1024):0;
$imgwidth = $imgheight = $_POST['width-height']?intval($_POST['width-height']):300;
//自定定义文件上传大小
ini_set('upload_max_filesize',$size);
$mathsize = str_replace('M','',$size);
if($imgsize>$mathsize){
echo "图片大小不得超过{$size}!";
return;
}
if($file_name = _file_type($_FILES['img']['type'])){
if($_FILES['img']['error'] == UPLOAD_ERR_OK){
$savepath = 'upload/';
if(!is_dir($savepath)){
mkdir($savepath,0644);
}
//生成缩略图
$thumb_file = _make_thumb($_FILES['img']['tmp_name'], $imgwidth, $imgheight, $savepath);
//move_uploaded_file($_FILES['img']['tmp_name'],$savepath.$file_name);
echo "生成后的图片为:<img src='".$thumb_file."' />";
}else{
echo $_FILES['img']['error'];
return;
}
}else{
echo "图片格式不正确,请上传jpg,gif,png的格式!";
return;
}
}else{
echo <<<EOT
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>缩放图片保存成正方形</title>
</head>
<body>
<form action="" method="POST" enctype="multipart/form-data">
<div>
<label>上传一张图片:</label>
<input type="file" name="img" />
</div>
<div>
<label>生成缩略图的宽高（单位px）:</label>
<input type="text" name="width-height" value="300" />
</div>
<div>
<label>文件大小上限:</label>
<input type="text" name="size" value="2M" />
</div>
<div><input type="submit" name="submit" value="提交" /></div>
</form>
</body>
</html>
EOT;
}