php缩略图代码，imagecopyresampled函数生成缩略图

3. function CreateImage($SrcImageUrl, $DirImageUrl, $Width, $Height)

4. {
5. $img;
6. $srcw;
7. $new_width;
8. $srch;
9. $new_height;
10. // 图片类型
11. $type = substr(strrchr($SrcImageUrl, "."), 1);
12. // 初始化图像
13. if($type == "jpg")
14. $img = imagecreatefromjpeg($SrcImageUrl);
15. if($type == "gif")
16. $img = imagecreatefromgif($SrcImageUrl);
17. if($type == "png")
18. $img = imagecreatefrompng($SrcImageUrl);

19. $srcw = imagesx($img);

20. $srch = imagesy($img);

21. if ($srcw / $srch > $Width / $Height)

22. {
23. if ($srcw > $Width)
24. {
25. $new_width = $Width;
26. $new_height = $srch * ($Width / $srcw);
27. }
28. else
29. {
30. $new_width = $srcw;
31. $new_height = $srch;
32. }
33. }
34. else
35. {
36. if ($srch > $Height)
37. {
38. $new_height = $Height;
39. $new_width = $srcw * ($Height / $srch);
40. }
41. else
42. {
43. $new_width = $srcw;
44. $new_height = $srch;
45. }
46. }

47. $new_image = imagecreatetruecolor($new_width, $new_height);

48. imagecopyresampled($new_image, $img, 0, 0, 0, 0, $new_width, $new_height, $srcw, $srch);
49. imagejpeg($new_image, $DirImageUrl);

50. imagedestroy($img);

51. imagedestroy($new_image);
52. }

3、改进后代码：

3. /*

4. *$o_photo 原图路径

5. *$d_photo 处理后图片路径

6. *$width 定义宽

7. *$height 定义高

8. *调用方法 cutphoto("test.jpg","temp.jpg",256,146);

9. */

10. function cutphoto($o_photo,$d_photo,$width,$height){

11. $temp_img = imagecreatefromjpeg($o_photo);

12. $o_width = imagesx($temp_img); //取得原图宽

13. $o_height = imagesy($temp_img); //取得原图高

14. //判断处理方法

15. if($width>$o_width || $height>$o_height){//原图宽或高比规定的尺寸小,进行压缩

16. $newwidth=$o_width;

17. $newheight=$o_height;

18. if($o_width>$width){

19. $newwidth=$width;

20. $newheight=$o_height*$width/$o_width;

21. }

22. if($newheight>$height){

23. $newwidth=$newwidth*$height/$newheight;

24. $newheight=$height;

25. }

26. //缩略图片

27. $new_img = imagecreatetruecolor($newwidth, $newheight);

28. imagecopyresampled($new_img, $temp_img, 0, 0, 0, 0, $newwidth, $newheight, $o_width, $o_height);

29. imagejpeg($new_img , $d_photo);

30. imagedestroy($new_img);

31. }else{//原图宽与高都比规定尺寸大,进行压缩后裁剪

32. if($o_height*$width/$o_width>$height){//先确定width与规定相同,如果height比规定大,则ok

33. $newwidth=$width;

34. $newheight=$o_height*$width/$o_width;

35. $x=0;

36. $y=($newheight-$height)/2;

37. }else{ //否则确定height与规定相同,width自适应

38. $newwidth=$o_width*$height/$o_height;

39. $newheight=$height;

40. $x=($newwidth-$width)/2;

41. $y=0;

42. }

43. //缩略图片

44. $new_img = imagecreatetruecolor($newwidth, $newheight);

45. imagecopyresampled($new_img, $temp_img, 0, 0, 0, 0, $newwidth, $newheight, $o_width, $o_height);

46. imagejpeg($new_img , $d_photo);

47. imagedestroy($new_img);

48. $temp_img = imagecreatefromjpeg($d_photo);

49. $o_width = imagesx($temp_img); //取得缩略图宽

50. $o_height = imagesy($temp_img); //取得缩略图高

51. //裁剪图片

52. $new_imgx = imagecreatetruecolor($width,$height);

53. imagecopyresampled($new_imgx,$temp_img,0,0,$x,$y,$width,$height,$width,$height);

54. imagejpeg($new_imgx , $d_photo);

55. imagedestroy($new_imgx);

56. }
57. }
58. ?>