这篇文章给大家分享的是使用php实现的等比例缩放图片及剪切图片的代码，非常的简单实用，附上用法，有需要的小伙伴可以参考下。

php等比例缩放图片及剪切图片代码分享

1. /**
2. * 图片缩放函数（可设置高度固定，宽度固定或者最大宽高，支持gif/jpg/png三种类型）
3. * Author : Specs
4. *
5. * @param string $source_path 源图片
6. * @param int $target_width 目标宽度
7. * @param int $target_height 目标高度
8. * @param string $fixed_orig 锁定宽高（可选参数 width、height或者空值）
9. * @return string
10. */
11. function myImageResize($source_path, $target_width = 200, $target_height = 200, $fixed_orig = ''){
12. $source_info = getimagesize($source_path);
13. $source_width = $source_info[0];
14. $source_height = $source_info[1];
15. $source_mime = $source_info['mime'];
16. $ratio_orig = $source_width / $source_height;
17. if ($fixed_orig == 'width'){
18. //宽度固定
19. $target_height = $target_width / $ratio_orig;
20. }elseif ($fixed_orig == 'height'){
21. //高度固定
22. $target_width = $target_height * $ratio_orig;
23. }else{
24. //最大宽或最大高
25. if ($target_width / $target_height > $ratio_orig){
26. $target_width = $target_height * $ratio_orig;
27. }else{
28. $target_height = $target_width / $ratio_orig;
29. }
30. }
31. switch ($source_mime){
32. case 'image/gif':
33. $source_image = imagecreatefromgif($source_path);
34. break;
35. case 'image/jpeg':
36. $source_image = imagecreatefromjpeg($source_path);
37. break;
38. case 'image/png':
39. $source_image = imagecreatefrompng($source_path);
40. break;
41. default:
42. return false;
43. break;
44. }
45. $target_image = imagecreatetruecolor($target_width, $target_height);
46. imagecopyresampled($target_image, $source_image, 0, 0, 0, 0, $target_width, $target_height, $source_width, $source_height);
47. //header('Content-type: image/jpeg');
48. $imgArr = explode('.', $source_path);
49. $target_path = $imgArr[0] . '_new.' . $imgArr[1];
50. imagejpeg($target_image, $target_path, 100);
51. }

用法：

myImageResize($filename, 200, 200); //最大宽高

myImageResize($filename, 200, 200, 'width'); //宽度固定

myImageResize($filename, 200, 200, 'height'); //高度固定

剪切图片为固定大小：

1. function imagecropper($source_path, $target_width, $target_height){
2. $source_info = getimagesize($source_path);
3. $source_width = $source_info[0];
4. $source_height = $source_info[1];
5. $source_mime = $source_info['mime'];
6. $source_ratio = $source_height / $source_width;
7. $target_ratio = $target_height / $target_width;
8. // 源图过高
9. if ($source_ratio > $target_ratio){
10. $cropped_width = $source_width;
11. $cropped_height = $source_width * $target_ratio;
12. $source_x = 0;
13. $source_y = ($source_height - $cropped_height) / 2;
14. }elseif ($source_ratio < $target_ratio){ // 源图过宽
15. $cropped_width = $source_height / $target_ratio;
16. $cropped_height = $source_height;
17. $source_x = ($source_width - $cropped_width) / 2;
18. $source_y = 0;
19. }else{ // 源图适中
20. $cropped_width = $source_width;
21. $cropped_height = $source_height;
22. $source_x = 0;
23. $source_y = 0;
24. }
25. switch ($source_mime){
26. case 'image/gif':
27. $source_image = imagecreatefromgif($source_path);
28. break;
29. case 'image/jpeg':
30. $source_image = imagecreatefromjpeg($source_path);
31. break;
32. case 'image/png':
33. $source_image = imagecreatefrompng($source_path);
34. break;
35. default:
36. return false;
37. break;
38. }
39. $target_image = imagecreatetruecolor($target_width, $target_height);
40. $cropped_image = imagecreatetruecolor($cropped_width, $cropped_height);
41. // 裁剪
42. imagecopy($cropped_image, $source_image, 0, 0, $source_x, $source_y, $cropped_width, $cropped_height);
43. // 缩放
44. imagecopyresampled($target_image, $cropped_image, 0, 0, 0, 0, $target_width, $target_height, $cropped_width, $cropped_height);
45. $dotpos = strrpos($source_path, '.');
46. $imgName = substr($source_path, 0, $dotpos);
47. $suffix = substr($source_path, $dotpos);
48. $imgNew = $imgName . '_small' . $suffix;
49. imagejpeg($target_image, $imgNew, 100);
50. imagedestroy($source_image);
51. imagedestroy($target_image);
52. imagedestroy($cropped_image);
53. }