PHP上传图片进行等比缩放可增加水印功能_php技巧

/** 
* 
* @author zhao jinhan 
* @date 2014年1月13日11:54:30 
* @email xb_zjh@126.com 
* 
*/ 
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:"; 
}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; 
}