Title: Image upload / GDLib / WordPress hooks
Last modified: August 21, 2016

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# Image upload / GDLib / WordPress hooks

 *  [thorakmedichi](https://wordpress.org/support/users/thorakmedichi/)
 * (@thorakmedichi)
 * [13 years, 2 months ago](https://wordpress.org/support/topic/image-upload-gdlib-wordpress-hooks/)
 * Ok so I have a bit of an odd situation that I need help with. What I am trying
   to do with my custom plugin is have images that are uploaded for a custom post
   be stored in a special directory – which I have accomplished using the wp_handle_upload().
   The thing is I also needed to have a new custom image size for the specific post
   type – which again I accomplished using add_image_size(). So far all of this 
   is working perfectly. My next step has me stumped though…
 * I need to run a bunch of GDlib processing on JUST the new image size I have created
   and named using the WordPress hooks. For sake of discussion I used add_image_size(‘
   google-marker’,100,100, false);
 * Now I dont want to change anything about the other files WordPress creates based
   on the media settings. I just want to change ‘google-marker’ to have a border
   and a little arrow pointer (which I know how to do in GDlib already)… I just 
   dont know how to hook into wordpress to intercept the default image resizing 
   and create my own.
 * Any pointers, help, links for things similer etc are all much appreciated.
 * Cheers

Viewing 2 replies - 1 through 2 (of 2 total)

 *  Thread Starter [thorakmedichi](https://wordpress.org/support/users/thorakmedichi/)
 * (@thorakmedichi)
 * [13 years, 2 months ago](https://wordpress.org/support/topic/image-upload-gdlib-wordpress-hooks/#post-3644104)
 * I should add that I know I can do this dynamically when the image displays but
   given the amount of images loading at once I think that going that approach is
   far more server intensive than just creating them on upload.
 *  Moderator [bcworkz](https://wordpress.org/support/users/bcworkz/)
 * (@bcworkz)
 * [13 years, 2 months ago](https://wordpress.org/support/topic/image-upload-gdlib-wordpress-hooks/#post-3644177)
 * I’m unfamiliar with the precise data flow WP follows to create the various sizes,
   so this may be a bogus lead.
 * It appears the hook you want is the ‘image_downsize’ filter. It is applied in
   wp-includes/media.php at lines 148 and 1386. Review the source code for specifics
   on how to return data. You should be able to discern if the image should be processed
   mostly just from the $size parameter passed from the sounds of things. Of course
   you would also need to check if the modified image file already exists, no point
   doing it more than once.

Viewing 2 replies - 1 through 2 (of 2 total)

The topic ‘Image upload / GDLib / WordPress hooks’ is closed to new replies.

## Tags

 * [Image Manipulation](https://wordpress.org/support/topic-tag/image-manipulation/)
 * [media upload](https://wordpress.org/support/topic-tag/media-upload/)
 * [wordpress hooks](https://wordpress.org/support/topic-tag/wordpress-hooks/)

 * In: [Hacks](https://wordpress.org/support/forum/plugins-and-hacks/hacks/)
 * 2 replies
 * 2 participants
 * Last reply from: [bcworkz](https://wordpress.org/support/users/bcworkz/)
 * Last activity: [13 years, 2 months ago](https://wordpress.org/support/topic/image-upload-gdlib-wordpress-hooks/#post-3644177)
 * Status: not resolved

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