1 <?php
2 function resizeImage($im,$maxwidth,$maxheight,$name,$filetype)
3 {
4 $pic_width = imagesx($im);
5 $pic_height = imagesy($im);
6
7 if(($maxwidth && $pic_width > $maxwidth) || ($maxheight && $pic_height > $maxheight))
8 {
9 if($maxwidth && $pic_width>$maxwidth)
10 {
11 $widthratio = $maxwidth/$pic_width;
12 $resizewidth_tag = true;
13 }
14
15 if($maxheight && $pic_height>$maxheight)
16 {
17 $heightratio = $maxheight/$pic_height;
18 $resizeheight_tag = true;
19 }
20
21 if($resizewidth_tag && $resizeheight_tag)
22 {
23 if($widthratio<$heightratio)
24 $ratio = $widthratio;
25 else
26 $ratio = $heightratio;
27 }
28
29 if($resizewidth_tag && !$resizeheight_tag)
30 $ratio = $widthratio;
31 if($resizeheight_tag && !$resizewidth_tag)
32 $ratio = $heightratio;
33
34 $newwidth = $pic_width * $ratio;
35 $newheight = $pic_height * $ratio;
36
37 if(function_exists("imagecopyresampled"))
38 {
39 $newim = imagecreatetruecolor($newwidth,$newheight);//PHP系统函数
40 imagecopyresampled($newim,$im,0,0,0,0,$newwidth,$newheight,$pic_width,$pic_height);//PHP系统函数
41 }
42 else
43 {
44 $newim = imagecreate($newwidth,$newheight);
45 imagecopyresized($newim,$im,0,0,0,0,$newwidth,$newheight,$pic_width,$pic_height);
46 }
47
48 $name = $name.$filetype;
49 imagejpeg($newim,$name);
50 imagedestroy($newim);
51 }
52 else
53 {
54 $name = $name.$filetype;
55 imagejpeg($im,$name);
56 }
57 }
58 //使用方法：
59 $im=imagecreatefromjpeg("1.jpg");//参数是图片的存方路径
60 $maxwidth="600";//设置图片的最大宽度
61 $maxheight="400";//设置图片的最大高度
62 $name="123";//图片的名称，随便取吧
63 $filetype=".jpg";//图片类型
64 resizeImage($im,$maxwidth,$maxheight,$name,$filetype);//调用上面的函数