phpgd库实现图片大小裁剪与缩放

2. //图片裁剪、缩放函数
3. //$filepath图片路径,$percent缩放百分比
4. function imagepress($filepath,$percent='0.5'){
5. // 图片类型
6. header('Content-Type: image/jpeg');
7. // 获得新的图片大小
8. list($width, $height) = getimagesize($filepath);
9. $new_width = $width * $percent;
10. $new_height = $height * $percent;
11. // 重新取样
12. $image_p = imagecreatetruecolor($new_width, $new_height);
13. $image = imagecreatefromjpeg($filepath);
14. imagecopyresampled($image_p, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height);
15. // 输出
16. return imagejpeg($image_p, null, 100);
17. }

原图:

效果图:

例子：

3. //$filepath图片路径,$new_width新的宽度,$new_height新的高度

4. function imagepress($filepath, $new_width, $new_height)
5. {
6. $source_info = getimagesize($filepath);
7. $source_width = $source_info[0];
8. $source_height = $source_info[1];
9. $source_mime = $source_info['mime'];
10. $source_ratio = $source_height / $source_width;
11. $target_ratio = $new_height / $new_width;

12. // 源图过高

13. if ($source_ratio > $target_ratio)
14. {
15. $cropped_width = $source_width;
16. $cropped_height = $source_width * $target_ratio;
17. $source_x = 0;
18. $source_y = ($source_height - $cropped_height) / 2;
19. }
20. // 源图过宽
21. elseif ($source_ratio < $target_ratio)
22. {
23. $cropped_width = $source_height / $target_ratio;
24. $cropped_height = $source_height;
25. $source_x = ($source_width - $cropped_width) / 2;
26. $source_y = 0;
27. }
28. // 源图适中
29. else
30. {
31. $cropped_width = $source_width;
32. $cropped_height = $source_height;
33. $source_x = 0;
34. $source_y = 0;
35. }
36. switch ($source_mime)
37. {
38. case 'image/gif':
39. $source_image = imagecreatefromgif($filepath);
40. break;
41. case 'image/jpeg':
42. $source_image = imagecreatefromjpeg($filepath);
43. break;
44. case 'image/png':
45. $source_image = imagecreatefrompng($filepath);
46. break;
47. default:
48. return false;
49. break;
50. }
51. $target_image = imagecreatetruecolor($new_width, $new_height);
52. $cropped_image = imagecreatetruecolor($cropped_width, $cropped_height);
53. // 裁剪
54. imagecopy($cropped_image, $source_image, 0, 0, $source_x, $source_y, $cropped_width, $cropped_height);
55. // 缩放
56. imagecopyresampled($target_image, $cropped_image, 0, 0, 0, 0, $new_width, $new_height, $cropped_width, $cropped_height);
57. header('Content-Type: image/jpeg');
58. imagejpeg($target_image);
59. imagedestroy($source_image);
60. imagedestroy($target_image);
61. imagedestroy($cropped_image);
62. }