Hey
Uploading an image, via ACF as usual, but I need to create multiple sized versions of that same image.
I could just use the regular add_image_size but, this means any other image uploaded, also gets created at these sizes which is not what I want (there will be around 100+ post_thumbnails created each time).
So, my question:
Using ACF to upload an image, how would I then create multiple sized copies of that image?
If you do not want to use add_image_size() for all the image sizes you need then what you need to do is create an acf/save_post filter. In this filter you would use a combination of WP functions.
$imagedata = wp_get_attachment_metadata($attachment_id);
to get all of the existing metadata
$resized = image_make_intermediate_size(get_attached_file($attachment_id), $width, $height, $crop);
to have WP create the new image size
$imagedata['sizes'][$name] = $resized;
to append your new size with your new name to the metadata
and then update the metadata wp_update_attachment_metadata($attachment_id, $imagedata);
I should add that, if you use any plugin that automatically rebuilds thumbnails your custom image sized created in this manner will be deleted from the image metadata.