1. filename ='img/test.jpg' 
2. $all_type=array( 
3. "jpg" =>array("create"=>"ImageCreateFromjpeg","output"=>"imagejpeg" ,"exn"=>".jpg"), 
4. "gif" =>array("create"=>"ImageCreateFromGIF","output"=>"imagegif" ,"exn"=>".gif"), 
5. "jpeg" =>array("create"=>"ImageCreateFromjpeg","output"=>"imagejpeg" ,"exn"=>".jpg"), 
6. "png" =>array("create"=>"imagecreatefrompng","output"=>"imagepng" ,"exn"=>".png"), 
7. "wbmp" =>array("create"=>"imagecreatefromwbmp","output"=>"image2wbmp","exn"=>".wbmp") 
8. ); 
9. $imgtype=getimagesize($filename); 
10. $width=$imgtype[0]; 
11. $height=$imgtype[1]; 
12. $type=str_replace('image/','',$imgtype['mime']); 
13. $func_create=$all_type[$type]['create']; 
14. $func_output=$all_type[$type]['output']; 
15. $x=$y=0; 
16. if(($width* 100)>($height* 120)) 
17. { 
18. $newwidth=ceil($height* 120/100); 
19. $newheight=$height; 
20. $x= ($width-$newwidth)/2; 
21. } 
22. elseif(($width* 100)<($height* 120)) 
23. { 
24. $newheight=ceil($width* 100/120); 
25. $newwidth=$width; 
26. $y= ($height-$newheight)/2; 
27. } 
28. else 
29. { 
30. $newheight=$height; 
31. $newwidth=$width; 
32. } 
33. // Load 
34. $thumb= imagecreatetruecolor($newwidth,$newheight); 
35. $source=$func_create($filename); 
36. // Resize 
37. imagecopyresized($thumb,$source, 0, 0, 0, 0,$newwidth,$newheight,$newwidth,$newheight); 
38. // Output 
39. $func_output($thumb,'a.jpeg'); 
40.  

原文链接：http://www.phpfensi.com/php/20180731/10968.html