PHP image cropping and scaling methods

2. /* Check whether the original file exists and obtain the information of the original file*/
3. $org_info = @getimagesize($img);
4. $img_org = $this->img_resource($img, $org_info[2] );
6. /* The size ratio of the original image and the thumbnail*/
7. $scale_org = $org_info[0] / $org_info[1];
8. /* Handle the situation where only the thumbnail width and height are 0, this When the background is the same size as the thumbnail*/
9. if ($thumb_width == 0 && $thumb_height == 0) {
10. $thumb_width = $org_info[0];
11. $thumb_height = $org_info[1];
12. } else {
13. if ($thumb_width == 0)
14. {
15. $thumb_width = $thumb_height * $scale_org;
16. }
17. if ($thumb_height == 0)
18. {
19. $thumb_height = $thumb_width / $scale_org;
20. }
21. }
23. / * Identifier for creating thumbnails*/
24. if ($gd == 2)
25. {
26. $img_thumb = imagecreatetruecolor($thumb_width, $thumb_height);
27. }
28. else
29. {
30. $img_thumb = imagecreate($thumb_width, $thumb_height) );
31. }
33. $clr = imagecolorallocate($img_thumb, 255, 255, 255);
34. imagefilledrectangle($img_thumb, 0, 0, $thumb_width, $thumb_height, $clr);
36. if ($org_info[0] / $thumb_width > Subject*/
37. $lessen_width = $thumb_height * $scale_org;
38. $lessen_height = $thumb_height;
39. }
41. $dst_x = ($thumb_width - $lessen_width) / 2;
42. $dst_y = ($thumb_height - $lessen_height) / 2;
44. /* Scale the original image*/
45. if ($gd == 2)
46. {
47. imagecopyresampled($img_thumb, $img_org, $dst_x, $dst_y, 0, 0, $lessen_width, $lessen_height, $org_info[0], $org_info[1]);
48. }
49. else
50. {
51. imagecopyresized($img_thumb, $img_org, $dst_x, $dst_y, 0, 0, $lessen_width, $lessen_height, $org_info[0], $org_info[1]);
52. }
56. Copy code
59. The second one is to cut the specified width and height directly from the original image and use it if you don’t want white edges to appear. This method can be divided into azimuth mode and fixed-point mode. The azimuth mode can be divided into 9 points according to the left, middle and right directions of the top, middle and bottom ends as the starting point of cutting, while the fixed-point mode allows the user to define the starting point of cutting. This method also first creates a white image of a specified size as the screen, (bbs.it-home.org) and then uses the imagecopy function to cut out a picture of a specified size and position on the original image, and then uses the imagecopyresampled function to cover the cut image. to the screen.

Advantages: It can basically guarantee that the white background area will not appear in the image, and the entire image space can be filled with the content of the original image; Disadvantage: Fatal disadvantage, the thumbnail cannot fully reflect the content of the original image. For example, for some character images, if the top left side is used as the cutting starting point, only half of the face may appear. Therefore, when choosing between the two modes, you need to do it according to your actual needs.

/* Create thumbnail identifier */

if ($gd == 2)
1. {
2. $img_thumb = imagecreatetruecolor($thumb_width, $thumb_height);
3. }
4. else
5. {
6. $img_thumb = imagecreate($thumb_width, $thumb_height) ;
7. }
9. $clr = imagecolorallocate($img_thumb, 255, 255, 255);
10. imagefilledrectangle($img_thumb, 0, 0, $thumb_width, $thumb_height, $clr);
12. /* Calculate the width of the cropped image and height*/
13. $mid_width = ($org_info[0] < $thumb_width) ? $org_info[0] : $thumb_width;
14. $mid_height = ($org_info[1] < $thumb_height) ? $org_info[1] : $thumb_height;
15. // Create a background artboard for the cut image
16. $mid_img = imagecreatetruecolor($mid_width, $mid_height);
17. //Copy the cut image data to the artboard to generate the cut image
18. imagecopy($mid_img, $ img_org, 0, 0, 0, 0, $mid_width, $mid_height);
19. /* Scale the original image*/
20. if ($gd == 2)
21. {
22. imagecopyresampled($img_thumb, $mid_img, 0, 0, 0, 0, $thumb_width, $thumb_height, $mid_width, $mid_height);
23. }
24. else
25. {
26. imagecopyresized($img_thumb, $mid_img, 0, 0, 0, 0, $thumb_width, $thumb_height, $mid_width , $mid_height);
27. }
30. Copy code