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img_caption_shortcode() WP 2.6.0

Builds the Caption shortcode output.

Allows a plugin to replace the content that would otherwise be returned. The filter is 'img_caption_shortcode' and passes an empty string, the attr parameter and the content parameter values.

The supported attributes for the shortcode are 'id', 'align', 'width', and 'caption'.

Hooks in function
Return

String. HTML content to display the caption.

Usage

img_caption_shortcode( $attr, $content );
$attr(array) (required)

Attributes of the caption shortcode.

  • $id (string)
    ID of the div element for the caption.

  • $align (string)
    Class name that aligns the caption. Accepts 'alignleft', 'aligncenter', alignright', 'alignnone'.
    Default: 'alignnone'

  • $width (int)
    The width of the caption, in pixels.

  • $caption (string)
    The caption text.

  • $class (string)
    Additional class name(s) added to the caption container.
$content(string)
Shortcode content.
Default: null

Code of img caption shortcode: wp-includes/media.php VER 5.0.3

<?php
function img_caption_shortcode( $attr, $content = null ) {
	// New-style shortcode with the caption inside the shortcode with the link and image tags.
	if ( ! isset( $attr['caption'] ) ) {
		if ( preg_match( '#((?:<a [^>]+>\s*)?<img [^>]+>(?:\s*</a>)?)(.*)#is', $content, $matches ) ) {
			$content = $matches[1];
			$attr['caption'] = trim( $matches[2] );
		}
	} elseif ( strpos( $attr['caption'], '<' ) !== false ) {
		$attr['caption'] = wp_kses( $attr['caption'], 'post' );
	}

	/**
	 * Filters the default caption shortcode output.
	 *
	 * If the filtered output isn't empty, it will be used instead of generating
	 * the default caption template.
	 *
	 * @since 2.6.0
	 *
	 * @see img_caption_shortcode()
	 *
	 * @param string $output  The caption output. Default empty.
	 * @param array  $attr    Attributes of the caption shortcode.
	 * @param string $content The image element, possibly wrapped in a hyperlink.
	 */
	$output = apply_filters( 'img_caption_shortcode', '', $attr, $content );
	if ( $output != '' )
		return $output;

	$atts = shortcode_atts( array(
		'id'	  => '',
		'align'	  => 'alignnone',
		'width'	  => '',
		'caption' => '',
		'class'   => '',
	), $attr, 'caption' );

	$atts['width'] = (int) $atts['width'];
	if ( $atts['width'] < 1 || empty( $atts['caption'] ) )
		return $content;

	if ( ! empty( $atts['id'] ) )
		$atts['id'] = 'id="' . esc_attr( sanitize_html_class( $atts['id'] ) ) . '" ';

	$class = trim( 'wp-caption ' . $atts['align'] . ' ' . $atts['class'] );

	$html5 = current_theme_supports( 'html5', 'caption' );
	// HTML5 captions never added the extra 10px to the image width
	$width = $html5 ? $atts['width'] : ( 10 + $atts['width'] );

	/**
	 * Filters the width of an image's caption.
	 *
	 * By default, the caption is 10 pixels greater than the width of the image,
	 * to prevent post content from running up against a floated image.
	 *
	 * @since 3.7.0
	 *
	 * @see img_caption_shortcode()
	 *
	 * @param int    $width    Width of the caption in pixels. To remove this inline style,
	 *                         return zero.
	 * @param array  $atts     Attributes of the caption shortcode.
	 * @param string $content  The image element, possibly wrapped in a hyperlink.
	 */
	$caption_width = apply_filters( 'img_caption_shortcode_width', $width, $atts, $content );

	$style = '';
	if ( $caption_width ) {
		$style = 'style="width: ' . (int) $caption_width . 'px" ';
	}

	if ( $html5 ) {
		$html = '<figure ' . $atts['id'] . $style . 'class="' . esc_attr( $class ) . '">'
		. do_shortcode( $content ) . '<figcaption class="wp-caption-text">' . $atts['caption'] . '</figcaption></figure>';
	} else {
		$html = '<div ' . $atts['id'] . $style . 'class="' . esc_attr( $class ) . '">'
		. do_shortcode( $content ) . '<p class="wp-caption-text">' . $atts['caption'] . '</p></div>';
	}

	return $html;
}