wp_generate_attachment_metadata( int $attachment_id, string $file ): array

Compatibility

Present in every tracked release (6.7.7 to 7.1.0), and compiles on PHP 7.4 through 8.6-dev.

Parameters

$attachment_idint

Attachment ID to process.

$filestring

Filepath of the attached image.

Return value

array

Metadata for attachment.

Performance profile

How much work a call to wp_generate_attachment_metadata() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.

Cost class

Heavy

Reads or writes the filesystem via file_exists().

Scaling

Constant

No loop in the body: the same number of instructions runs whatever you pass in.

Instructions

36–170

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 284.

Plugin surface

3 hooks

Third-party callbacks on 'attachment_thumbnail_args', 'fallback_intermediate_image_sizes', 'wp_generate_attachment_metadata' run inside this call, and their cost is not bounded by anything here.

Called by

13

13 places in core call this, so the cost is paid more often than your own code shows.

What it touches

• querycontent queryget_post()called directly
• hookthird-party callbacksapply_filters()called directly
• filesystemfilesystem accessfile_exists()called directly
• optionoption read or writeget_option()one call below wp_generate_attachment_metadata()

Further down the call graph this can also reach serialize, cache and transient. Those are the worst case, several calls deep and usually down an error path, not what a normal call pays.

What one call costs · 288 distinct outcomes

One number would be a lie: the work depends on which branch runs. These are every distinct cost wp_generate_attachment_metadata() can have, taken from its control-flow graph on PHP 8.5.

Hooks and filters fired · 3

3 hooks fire while wp_generate_attachment_metadata() runs, in this order:

1. 1
   apply_filters( attachment_thumbnail_args )filterline 660 (+81 into the body)

   Filters the parameters for the attachment thumbnail creation.

2. 2
   apply_filters( fallback_intermediate_image_sizes )filterline 686 (+107 into the body)

   Filters the image sizes generated for non-image mime types.

3. 3
   apply_filters( wp_generate_attachment_metadata )filterline 750 (+171 into the body)

   Filters the generated attachment meta data.

Uses · 24

• get_post()Retrieves post data given a post ID or post object.
• get_post_mime_type()Retrieves the mime type of an attachment based on the ID.
• file_is_displayable_image()Validates that file is suitable for displaying within a web page.
• wp_create_image_subsizes()Creates image sub-sizes, adds the new data to the image meta `sizes` array, and updates the image metadata.
• wp_attachment_is()Verifies an attachment is of a given type.
• wp_read_video_metadata()Retrieves metadata from a video file's ID3 tags.
• current_theme_supports()Checks a theme's support for a given feature.
• post_type_supports()Checks a post type's support for a given feature.
• wp_read_audio_metadata()Retrieves metadata from an audio file's ID3 tags.
• get_posts()Retrieves an array of the latest posts, or posts matching the given criteria.
• update_post_meta()Updates a post meta field based on the given post ID.
• wp_basename()i18n-friendly version of basename().

Used by · 13

• Custom_Background::handle_upload()Handles an Image upload for the background image.
• Custom_Image_Header::insert_attachment()Inserts an attachment and its metadata.
• Custom_Image_Header::step_2()Displays second step of custom header image page.
• WP_Customize_Manager::import_theme_starter_content()Imports theme starter content into the customized state.
• WP_REST_Attachments_Controller::create_item()Creates a single attachment.
• WP_REST_Attachments_Controller::edit_media_item()Applies edits to a media item and creates a new attachment record.
• WP_Site_Icon::insert_attachment()Inserts an attachment.
• media_handle_sideload()Handles a side-loaded file in the same way as an uploaded file is handled by media_handle_upload().
• media_handle_upload()Saves a file submitted from a POST request and create an attachment post for it.
• wp_ajax_crop_image()Handles cropping an image via AJAX.
• wp_generate_attachment_metadata()Generates attachment meta data and create image sub-sizes for images.
• wp_maybe_generate_attachment_metadata()Maybe attempts to generate attachment metadata, if missing.

Source code

View on Trac ↗View on GitHub ↗

579function wp_generate_attachment_metadata( $attachment_id, $file ) {580	$attachment = get_post( $attachment_id );581 582	$metadata  = array();583	$support   = false;584	$mime_type = get_post_mime_type( $attachment );585 586	if ( 'image/heic' === $mime_type || ( preg_match( '!^image/!', $mime_type ) && file_is_displayable_image( $file ) ) ) {587		// Make thumbnails and other intermediate sizes.588		$metadata = wp_create_image_subsizes( $file, $attachment_id );589	} elseif ( wp_attachment_is( 'video', $attachment ) ) {590		$metadata = wp_read_video_metadata( $file );591		$support  = current_theme_supports( 'post-thumbnails', 'attachment:video' ) || post_type_supports( 'attachment:video', 'thumbnail' );592	} elseif ( wp_attachment_is( 'audio', $attachment ) ) {593		$metadata = wp_read_audio_metadata( $file );594		$support  = current_theme_supports( 'post-thumbnails', 'attachment:audio' ) || post_type_supports( 'attachment:audio', 'thumbnail' );595	}596 597	/*598	 * wp_read_video_metadata() and wp_read_audio_metadata() return `false`599	 * if the attachment does not exist in the local filesystem,600	 * so make sure to convert the value to an array.601	 */602	if ( ! is_array( $metadata ) ) {603		$metadata = array();604	}605 606	if ( $support && ! empty( $metadata['image']['data'] ) ) {607		// Check for existing cover.608		$hash   = md5( $metadata['image']['data'] );609		$posts  = get_posts(610			array(611				'fields'         => 'ids',612				'post_type'      => 'attachment',613				'post_mime_type' => $metadata['image']['mime'],614				'post_status'    => 'inherit',615				'posts_per_page' => 1,616				'meta_key'       => '_cover_hash',617				'meta_value'     => $hash,618			)619		);620		$exists = reset( $posts );621 622		if ( ! empty( $exists ) ) {623			update_post_meta( $attachment_id, '_thumbnail_id', $exists );624		} else {625			$ext = '.jpg';626			switch ( $metadata['image']['mime'] ) {627				case 'image/gif':628					$ext = '.gif';629					break;630				case 'image/png':631					$ext = '.png';632					break;633				case 'image/webp':634					$ext = '.webp';635					break;636			}637			$basename = str_replace( '.', '-', wp_basename( $file ) ) . '-image' . $ext;638			$uploaded = wp_upload_bits( $basename, '', $metadata['image']['data'] );639			if ( false === $uploaded['error'] ) {640				$image_attachment = array(641					'post_mime_type' => $metadata['image']['mime'],642					'post_type'      => 'attachment',643					'post_content'   => '',644				);645				/**646				 * Filters the parameters for the attachment thumbnail creation.647				 *648				 * @since 3.9.0649				 *650				 * @param array $image_attachment An array of parameters to create the thumbnail.651				 * @param array $metadata         Current attachment metadata.652				 * @param array $uploaded         {653				 *     Information about the newly-uploaded file.654				 *655				 *     @type string $file  Filename of the newly-uploaded file.656				 *     @type string $url   URL of the uploaded file.657				 *     @type string $type  File type.658				 * }

Changelog

Introduced in 2.1.0. Unchanged from 6.7.7 through 7.1.0.

1. 6.7.7
2. 6.8.8
3. 6.9.7
4. 7.0.4
5. 7.1.0

Signature, return type and hooks compared across 5 parsed releases.

About this page

Parsed data

Generated from the wordpress-develop 6.8.8 tag, from src/wp-admin/includes/image.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.

Corrections

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