Low-level function to create image sub-sizes.
Description
Updates the image meta after each sub-size is created.
Errors are stored in the returned image metadata array.
Parameters
$new_sizesarrayrequired- Array defining what sizes to create.
$filestringrequired- Full path to the image file.
$image_metaarrayrequired- The attachment meta data array.
$attachment_idintrequired- Attachment ID to process.
Source
function _wp_make_subsizes( $new_sizes, $file, $image_meta, $attachment_id ) {
if ( empty( $image_meta ) || ! is_array( $image_meta ) ) {
// Not an image attachment.
return array();
}
// Check if any of the new sizes already exist.
if ( isset( $image_meta['sizes'] ) && is_array( $image_meta['sizes'] ) ) {
foreach ( $image_meta['sizes'] as $size_name => $size_meta ) {
/*
* Only checks "size name" so we don't override existing images even if the dimensions
* don't match the currently defined size with the same name.
* To change the behavior, unset changed/mismatched sizes in the `sizes` array in image meta.
*/
if ( array_key_exists( $size_name, $new_sizes ) ) {
unset( $new_sizes[ $size_name ] );
}
}
} else {
$image_meta['sizes'] = array();
}
if ( empty( $new_sizes ) ) {
// Nothing to do...
return $image_meta;
}
/*
* Sort the image sub-sizes in order of priority when creating them.
* This ensures there is an appropriate sub-size the user can access immediately
* even when there was an error and not all sub-sizes were created.
*/
$priority = array(
'medium' => null,
'large' => null,
'thumbnail' => null,
'medium_large' => null,
);
$new_sizes = array_filter( array_merge( $priority, $new_sizes ) );
$editor = wp_get_image_editor( $file );
if ( is_wp_error( $editor ) ) {
// The image cannot be edited.
return $image_meta;
}
// If stored EXIF data exists, rotate the source image before creating sub-sizes.
if ( ! empty( $image_meta['image_meta'] ) ) {
$rotated = $editor->maybe_exif_rotate();
if ( is_wp_error( $rotated ) ) {
// TODO: Log errors.
}
}
if ( method_exists( $editor, 'make_subsize' ) ) {
foreach ( $new_sizes as $new_size_name => $new_size_data ) {
$new_size_meta = $editor->make_subsize( $new_size_data );
if ( is_wp_error( $new_size_meta ) ) {
// TODO: Log errors.
} else {
// Save the size meta value.
$image_meta['sizes'][ $new_size_name ] = $new_size_meta;
wp_update_attachment_metadata( $attachment_id, $image_meta );
}
}
} else {
// Fall back to `$editor->multi_resize()`.
$created_sizes = $editor->multi_resize( $new_sizes );
if ( ! empty( $created_sizes ) ) {
$image_meta['sizes'] = array_merge( $image_meta['sizes'], $created_sizes );
wp_update_attachment_metadata( $attachment_id, $image_meta );
}
}
return $image_meta;
}
Changelog
| Version | Description |
|---|---|
| 5.3.0 | Introduced. |
I know this is an internal wp function not meant to be used in theme or plugin code, however using it is the only way I found to solve a problem: to programmatically create some additional image sizes when needed.
For example I have a plugin that when we upload some image to it, it needs to have that image in 3 specific sizes. This plugin solves that by registering those sizes via add_image_size. But this way those sizes (and files) are created for all images uploaded to website, but only some of them will be used for that plugin. That is bad if multiple plugins do that and if you have over 25k uploads on a website – it reaches tens of gigs in disk usage with all those unnecessary thumbnails for every upload.
So my solution to that is to remove_image_size for those plugin’s sizes, and to create needed sizes only for images actually used by that plugin based on some hook like so: