php GD库生成高质量缩略图(示例)

3. $FILENAME="image.thumb";

4. // 生成图片的宽度
5. $RESIZEWIDTH=400;
6. // 生成图片的高度
7. $RESIZEHEIGHT=400;

8. function ResizeImage($im,$maxwidth,$maxheight,$name){

9. $width = imagesx($im);
10. $height = imagesy($im);
11. if(($maxwidth && $width > $maxwidth) || ($maxheight && $height > $maxheight)){
12. if($maxwidth && $width > $maxwidth){
13. $widthratio = $maxwidth/$width;
14. $RESIZEWIDTH=true;
15. }
16. if($maxheight && $height > $maxheight){
17. $heightratio = $maxheight/$height;
18. $RESIZEHEIGHT=true;
19. }
20. if($RESIZEWIDTH && $RESIZEHEIGHT){
21. if($widthratio $ratio = $widthratio;
22. }else{
23. $ratio = $heightratio;
24. }
25. }elseif($RESIZEWIDTH){
26. $ratio = $widthratio;
27. }elseif($RESIZEHEIGHT){
28. $ratio = $heightratio;
29. }
30. $newwidth = $width * $ratio;
31. $newheight = $height * $ratio;
32. if(function_exists("imagecopyresampled")){
33. $newim = imagecreatetruecolor($newwidth, $newheight);
34. imagecopyresampled($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
35. }else{
36. $newim = imagecreate($newwidth, $newheight);
37. imagecopyresized($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
38. }
39. ImageJpeg ($newim,$name . ".jpg");
40. ImageDestroy ($newim);
41. }else{
42. ImageJpeg ($im,$name . ".jpg");
43. }
44. }

45. if($_FILES['image']['size']){

46. if($_FILES['image']['type'] == "image/pjpeg"){
47. $im = imagecreatefromjpeg($_FILES['image']['tmp_name']);
48. }elseif($_FILES['image']['type'] == "image/x-png"){
49. $im = imagecreatefrompng($_FILES['image']['tmp_name']);
50. }elseif($_FILES['image']['type'] == "image/gif"){
51. $im = imagecreatefromgif($_FILES['image']['tmp_name']);
52. }
53. if($im){
54. if(file_exists("$FILENAME.jpg")){
55. unlink("$FILENAME.jpg");
56. }
57. ResizeImage($im,$RESIZEWIDTH,$RESIZEHEIGHT,$FILENAME);
58. ImageDestroy ($im);
59. }
60. }
61. ?>

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2，测试代码(demo.php)

2. /**
3. * PHP生成高质量缩略图
4. * by bbs.it-home.org
5. */
6. include('ResizeImage.php');
7. if(!empty($_POST)){
8. echo($FILENAME.".jpg?cache=".rand(0,999999));
9. }
10. ?>

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