image_downsize( int $id, string|int[] $size = 'medium' ): 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

$idint

Attachment ID for image.

$sizestring|int[]optional

Image size. Accepts any registered image size name, or an array of width and height values in pixels (in that order). Default 'medium'.Default: 'medium'

Return value

array|false

Array of image data, or boolean false if no image is available.

• $0string

  Image source URL.

• $1int

  Image width in pixels.

• $2int

  Image height in pixels.

• $3bool

  Whether the image is a resized image.

Performance profile

How much work a call to image_downsize() 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

15–123

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 136.

Plugin surface

1 hook

Third-party callbacks on 'image_downsize' 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
• querycontent queryget_post()one call below image_downsize()
• optionoption read or writeget_option()one call below image_downsize()

Further down the call graph this can also reach cache, serialize 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 · 10 distinct outcomes

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

Hooks and filters fired · 1

One hook fires while image_downsize() runs, in this order:

1. 1
   apply_filters( image_downsize )filterline 212 (+16 into the body)

   Filters whether to preempt the output of image_downsize().

Uses · 9

• wp_attachment_is_image()Determines whether an attachment is an image.
• apply_filters()Calls the callback functions that have been added to a filter hook.
• wp_get_attachment_url()Retrieves the URL for an attachment.
• wp_get_attachment_metadata()Retrieves attachment metadata for attachment ID.
• wp_basename()i18n-friendly version of basename().
• image_get_intermediate_size()Retrieves the image's intermediate size (resized) path, width, and height.
• get_attached_file()Retrieves attached file path based on attachment ID.
• wp_getimagesize()Allows PHP's getimagesize() to be debuggable when necessary.
• image_constrain_size_for_editor()Scales down the default size of an image.

Used by · 4

• get_image_tag()Gets an img tag for an image attachment, scaling it down if requested.
• image_size_input_fields()Retrieves HTML for the size radio buttons with the specified one checked.
• wp_get_attachment_image_src()Retrieves an image to represent an attachment.
• wp_xmlrpc_server::_prepare_media_item()Prepares media item data for return in an XML-RPC object.

Source code

View on Trac ↗View on GitHub ↗

196function image_downsize( $id, $size = 'medium' ) {197	$is_image = wp_attachment_is_image( $id );198 199	/**200	 * Filters whether to preempt the output of image_downsize().201	 *202	 * Returning a truthy value from the filter will effectively short-circuit203	 * down-sizing the image, returning that value instead.204	 *205	 * @since 2.5.0206	 *207	 * @param bool|array   $downsize Whether to short-circuit the image downsize.208	 * @param int          $id       Attachment ID for image.209	 * @param string|int[] $size     Requested image size. Can be any registered image size name, or210	 *                               an array of width and height values in pixels (in that order).211	 */212	$out = apply_filters( 'image_downsize', false, $id, $size );213 214	if ( $out ) {215		return $out;216	}217 218	$img_url          = wp_get_attachment_url( $id );219	$meta             = wp_get_attachment_metadata( $id );220	$width            = 0;221	$height           = 0;222	$is_intermediate  = false;223	$img_url_basename = wp_basename( $img_url );224 225	/*226	 * If the file isn't an image, attempt to replace its URL with a rendered image from its meta.227	 * Otherwise, a non-image type could be returned.228	 */229	if ( ! $is_image ) {230		if ( ! empty( $meta['sizes']['full'] ) ) {231			$img_url          = str_replace( $img_url_basename, $meta['sizes']['full']['file'], $img_url );232			$img_url_basename = $meta['sizes']['full']['file'];233			$width            = $meta['sizes']['full']['width'];234			$height           = $meta['sizes']['full']['height'];235		} else {236			return false;237		}238	}239 240	// Try for a new style intermediate size.241	$intermediate = image_get_intermediate_size( $id, $size );242 243	if ( $intermediate ) {244		$img_url         = str_replace( $img_url_basename, $intermediate['file'], $img_url );245		$width           = $intermediate['width'];246		$height          = $intermediate['height'];247		$is_intermediate = true;248	} elseif ( 'thumbnail' === $size && ! empty( $meta['thumb'] ) && is_string( $meta['thumb'] ) ) {249		// Fall back to the old thumbnail.250		$imagefile = get_attached_file( $id );251		$thumbfile = str_replace( wp_basename( $imagefile ), wp_basename( $meta['thumb'] ), $imagefile );252 253		if ( file_exists( $thumbfile ) ) {254			$info = wp_getimagesize( $thumbfile );255 256			if ( $info ) {257				$img_url         = str_replace( $img_url_basename, wp_basename( $thumbfile ), $img_url );258				$width           = $info[0];259				$height          = $info[1];260				$is_intermediate = true;261			}262		}263	}264 265	if ( ! $width && ! $height && isset( $meta['width'], $meta['height'] ) ) {266		// Any other type: use the real image.267		$width  = $meta['width'];268		$height = $meta['height'];269	}270 271	if ( $img_url ) {272		// We have the actual image size, but might need to further constrain it if content_width is narrower.273		list( $width, $height ) = image_constrain_size_for_editor( $width, $height, $size );274 275		return array( $img_url, $width, $height, $is_intermediate );

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 7.0.4 tag, from src/wp-includes/media.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.

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