wp_read_image_metadata( string $file ): array|false

Description

Compatibility

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

Parameters

$filestring

Return value

array|false

Image metadata array on success, false on failure.

Performance profile

How much work a call to wp_read_image_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

Scales with input

The body loops, so the work grows with what you pass in.

Instructions

56–151

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 410.

Plugin surface

2 hooks

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

Called by

4

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

What it touches

• hookthird-party callbacksapply_filters()called directly
• filesystemfilesystem accessfile_exists()called directly

Further down the call graph this can also reach option, cache, serialize, query 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 · 11 distinct outcomes

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

This body has more branch combinations than are worth enumerating, so the table covers the outcomes found first rather than every one that exists.

Hooks and filters fired · 2

2 hooks fire while wp_read_image_metadata() runs, in this order:

1. 1
   apply_filters( wp_read_image_metadata_types )filterline 942 (+117 into the body)

   Filters the image types to check for exif data.

2. 2
   apply_filters( wp_read_image_metadata )filterline 1077 (+252 into the body)

   Filters the array of meta data read from an image's exif data.

Uses · 10

• wp_getimagesize()Allows PHP's getimagesize() to be debuggable when necessary.
• mbstring_binary_safe_encoding()Sets the mbstring internal encoding to a binary safe encoding when func_overload is enabled.
• reset_mbstring_encoding()Resets the mbstring internal encoding to a users previously set encoding.
• wp_get_image_alttext()Gets the alt text from image meta data.
• apply_filters()Calls the callback functions that have been added to a filter hook.
• wp_exif_frac2dec()Converts a fraction string to a decimal.
• wp_exif_date2ts()Converts the exif date format to a unix timestamp.
• wp_is_valid_utf8()Determines if a given byte string represents a valid UTF-8 encoding.
• utf8_encode()Converts a string from ISO-8859-1 to UTF-8.
• wp_kses_post_deep()Navigates through an array, object, or scalar, and sanitizes content for allowed HTML tags for post content.

Used by · 4

• WP_REST_Attachments_Controller::insert_attachment()Inserts the attachment post in the database. Does not update the attachment meta.
• 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_create_image_subsizes()Creates image sub-sizes, adds the new data to the image meta `sizes` array, and updates the image metadata.

Source code

View on Trac ↗View on GitHub ↗

825function wp_read_image_metadata( $file ) {826	if ( ! file_exists( $file ) ) {827		return false;828	}829 830	$image_size = wp_getimagesize( $file );831 832	if ( false === $image_size ) {833		return false;834	}835 836	list( , , $image_type ) = $image_size;837 838	/*839	 * EXIF contains a bunch of data we'll probably never need formatted in ways840	 * that are difficult to use. We'll normalize it and just extract the fields841	 * that are likely to be useful. Fractions and numbers are converted to842	 * floats, dates to unix timestamps, and everything else to strings.843	 */844	$meta = array(845		'aperture'          => 0,846		'credit'            => '',847		'camera'            => '',848		'caption'           => '',849		'created_timestamp' => 0,850		'copyright'         => '',851		'focal_length'      => 0,852		'iso'               => 0,853		'shutter_speed'     => 0,854		'title'             => '',855		'orientation'       => 0,856		'keywords'          => array(),857		'alt'               => '',858	);859 860	$iptc = array();861	$info = array();862	/*863	 * Read IPTC first, since it might contain data not available in exif such864	 * as caption, description etc.865	 */866	if ( is_callable( 'iptcparse' ) ) {867		wp_getimagesize( $file, $info );868 869		if ( ! empty( $info['APP13'] ) ) {870			// Don't silence errors when in debug mode, unless running unit tests.871			if ( defined( 'WP_DEBUG' ) && WP_DEBUG872				&& ! defined( 'WP_RUN_CORE_TESTS' )873			) {874				$iptc = iptcparse( $info['APP13'] );875			} else {876				// Silencing notice and warning is intentional. See https://core.trac.wordpress.org/ticket/42480877				$iptc = @iptcparse( $info['APP13'] );878			}879 880			if ( ! is_array( $iptc ) ) {881				$iptc = array();882			}883 884			// Headline, "A brief synopsis of the caption".885			if ( ! empty( $iptc['2#105'][0] ) ) {886				$meta['title'] = trim( $iptc['2#105'][0] );887				/*888				* Title, "Many use the Title field to store the filename of the image,889				* though the field may be used in many ways".890				*/891			} elseif ( ! empty( $iptc['2#005'][0] ) ) {892				$meta['title'] = trim( $iptc['2#005'][0] );893			}894 895			if ( ! empty( $iptc['2#120'][0] ) ) { // Description / legacy caption.896				$caption = trim( $iptc['2#120'][0] );897 898				mbstring_binary_safe_encoding();899				$caption_length = strlen( $caption );900				reset_mbstring_encoding();901 902				if ( empty( $meta['title'] ) && $caption_length < 80 ) {903					// Assume the title is stored in 2:120 if it's short.904					$meta['title'] = $caption;

Changelog

Introduced in 2.5.0. 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 7.1.0 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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