img_caption_shortcode( array $attr, string $content = '' ): string

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

$attrarray

Attributes of the caption shortcode.

• $idstring

  ID of the image and caption container element, i.e. <figure> or <div>.

• $caption_idstring

  ID of the caption element, i.e. <figcaption> or <p>.

• $alignstringdefault: 'alignnone'. Accepts 'alignleft', 'aligncenter', alignright', 'alignnone'

  Class name that aligns the caption.

• $widthint

  The width of the caption, in pixels.

• $captionstring

  The caption text.

• $classstring

  Additional class name(s) added to the caption container.

$contentstringoptional

Shortcode content. Default empty string.Default: ''

Return value

string

HTML content to display the caption.

Performance profile

How much work a call to img_caption_shortcode() 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

Trivial

Touches nothing outside its own arguments.

Scaling

Constant

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

Instructions

17–155

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 198.

Plugin surface

2 hooks

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

Called by

1

1 place 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

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 · 30 distinct outcomes

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

Hooks and filters fired · 2

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

1. 1
   apply_filters( img_caption_shortcode )filterline 2653 (+25 into the body)

   Filters the default caption shortcode output.

2. 2
   apply_filters( img_caption_shortcode_width )filterline 2735 (+107 into the body)

   Filters the width of an image's caption.

Uses · 9

• str_contains()Polyfill for `str_contains()` function added in PHP 8.0.
• wp_kses()Filters text content and strips out disallowed HTML.
• apply_filters()Calls the callback functions that have been added to a filter hook.
• shortcode_atts()Combines user attributes with known attributes and fill in defaults when needed.
• sanitize_html_class()Sanitizes an HTML classname to ensure it only contains valid characters.
• wp_unique_prefixed_id()Generates an incremental ID that is independent per each different prefix.
• esc_attr()Escaping for HTML attributes.
• current_theme_supports()Checks a theme's support for a given feature.
• do_shortcode()Searches content for shortcodes and filter shortcodes through their hooks.

Used by · 1

• WP_Widget_Media_Image::render_media()Render the media on the frontend.

Source code

View on Trac ↗View on GitHub ↗

2628function img_caption_shortcode( $attr, $content = '' ) {2629	// New-style shortcode with the caption inside the shortcode with the link and image tags.2630	if ( ! isset( $attr['caption'] ) ) {2631		if ( preg_match( '#((?:<a [^>]+>\s*)?<img [^>]+>(?:\s*</a>)?)(.*)#is', $content, $matches ) ) {2632			$content         = $matches[1];2633			$attr['caption'] = trim( $matches[2] );2634		}2635	} elseif ( str_contains( $attr['caption'], '<' ) ) {2636		$attr['caption'] = wp_kses( $attr['caption'], 'post' );2637	}2638 2639	/**2640	 * Filters the default caption shortcode output.2641	 *2642	 * If the filtered output isn't empty, it will be used instead of generating2643	 * the default caption template.2644	 *2645	 * @since 2.6.02646	 *2647	 * @see img_caption_shortcode()2648	 *2649	 * @param string $output  The caption output. Default empty.2650	 * @param array  $attr    Attributes of the caption shortcode.2651	 * @param string $content The image element, possibly wrapped in a hyperlink.2652	 */2653	$output = apply_filters( 'img_caption_shortcode', '', $attr, $content );2654 2655	if ( ! empty( $output ) ) {2656		return $output;2657	}2658 2659	/**2660	 * @var array{2661	 *     id: string,2662	 *     caption_id: string,2663	 *     align: string,2664	 *     width: string,2665	 *     caption: string,2666	 *     class: string,2667	 * } $atts2668	 */2669	$atts = shortcode_atts(2670		array(2671			'id'         => '',2672			'caption_id' => '',2673			'align'      => 'alignnone',2674			'width'      => '',2675			'caption'    => '',2676			'class'      => '',2677		),2678		$attr,2679		'caption'2680	);2681 2682	$atts['width'] = (int) $atts['width'];2683 2684	if ( $atts['width'] < 1 || empty( $atts['caption'] ) ) {2685		return $content;2686	}2687 2688	$id               = '';2689	$caption_id       = '';2690	$describedby      = '';2691	$unique_id_value  = '';2692	$caption_id_value = '';2693 2694	if ( $atts['id'] ) {2695		$atts['id']      = sanitize_html_class( $atts['id'] );2696		$unique_id_value = (string) preg_replace( '/-1$/', '', wp_unique_prefixed_id( $atts['id'] . '-' ) );2697		$id              = 'id="' . esc_attr( $unique_id_value ) . '" ';2698	}2699 2700	if ( $atts['caption_id'] ) {2701		// User explicitly provided a caption_id - make it unique.2702		$atts['caption_id'] = sanitize_html_class( $atts['caption_id'] );2703		$caption_id_value   = preg_replace( '/-1$/', '', wp_unique_prefixed_id( $atts['caption_id'] . '-' ) );2704	} elseif ( $unique_id_value ) {2705		// Derive from the already-unique figure ID - guaranteed unique, no need for second call.2706		$caption_id_value = 'caption-' . str_replace( '_', '-', $unique_id_value );2707	}

Changelog

Introduced in 2.6.0. 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-includes/media.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.

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