gallery_shortcode

	/**
	 * Filters whether to add the missing `width` and `height` HTML attributes to the img tag. Default `true`.
	 *
	 * Returning anything else than `true` will not add the attributes.
	 *
	 * @since 5.5.0
	 *
	 * @param bool   $value         The filtered value, defaults to `true`.
	 * @param string $image         The HTML `img` tag where the attribute should be added.
	 * @param string $context       Additional context about how the function was called or where the img tag is.
	 * @param int    $attachment_id The image attachment ID.
	 */
	$add = apply_filters( 'wp_img_tag_add_width_and_height_attr', true, $image, $context, $attachment_id );

	if ( true === $add ) {
		$image_meta = wp_get_attachment_metadata( $attachment_id );
		$size_array = wp_image_src_get_dimensions( $image_src, $image_meta, $attachment_id );

		if ( $size_array ) {
			$hw = trim( image_hwstring( $size_array[0], $size_array[1] ) );
			return str_replace( '<img', "<img {$hw}", $image );
		}
	}

	return $image;
}

/**
 * Adds `srcset` and `sizes` attributes to an existing `img` HTML tag.
 *
 * @since 5.5.0
 *
 * @param string $image         The HTML `img` tag where the attribute should be added.
 * @param string $context       Additional context to pass to the filters.
 * @param int    $attachment_id Image attachment ID.
 * @return string Converted 'img' element with 'loading' attribute added.
 */
function wp_img_tag_add_srcset_and_sizes_attr( $image, $context, $attachment_id ) {
	/**
	 * Filters whether to add the `srcset` and `sizes` HTML attributes to the img tag. Default `true`.
	 *
	 * Returning anything else than `true` will not add the attributes.
	 *
	 * @since 5.5.0
	 *
	 * @param bool   $value         The filtered value, defaults to `true`.
	 * @param string $image         The HTML `img` tag where the attribute should be added.
	 * @param string $context       Additional context about how the function was called or where the img tag is.
	 * @param int    $attachment_id The image attachment ID.
	 */
	$add = apply_filters( 'wp_img_tag_add_srcset_and_sizes_attr', true, $image, $context, $attachment_id );

	if ( true === $add ) {
		$image_meta = wp_get_attachment_metadata( $attachment_id );
		return wp_image_add_srcset_and_sizes( $image, $image_meta, $attachment_id );
	}

	return $image;
}

/**
 * Adds a 'wp-post-image' class to post thumbnails. Internal use only.
 *
 * Uses the {@see 'begin_fetch_post_thumbnail_html'} and {@see 'end_fetch_post_thumbnail_html'}
 * action hooks to dynamically add/remove itself so as to only filter post thumbnails.
 *
 * @ignore
 * @since 2.9.0
 *
 * @param string[] $attr Array of thumbnail attributes including src, class, alt, title, keyed by attribute name.
 * @return string[] Modified array of attributes including the new 'wp-post-image' class.
 */
function _wp_post_thumbnail_class_filter( $attr ) {
	$attr['class'] .= ' wp-post-image';
	return $attr;
}

/**
 * Adds '_wp_post_thumbnail_class_filter' callback to the 'wp_get_attachment_image_attributes'
 * filter hook. Internal use only.
 *
 * @ignore
 * @since 2.9.0
 *
 * @param string[] $attr Array of thumbnail attributes including src, class, alt, title, keyed by attribute name.
 */
function _wp_post_thumbnail_class_filter_add( $attr ) {
	add_filter( 'wp_get_attachment_image_attributes', '_wp_post_thumbnail_class_filter' );
}

/**
 * Removes the '_wp_post_thumbnail_class_filter' callback from the 'wp_get_attachment_image_attributes'
 * filter hook. Internal use only.
 *
 * @ignore
 * @since 2.9.0
 *
 * @param string[] $attr Array of thumbnail attributes including src, class, alt, title, keyed by attribute name.
 */
function _wp_post_thumbnail_class_filter_remove( $attr ) {
	remove_filter( 'wp_get_attachment_image_attributes', '_wp_post_thumbnail_class_filter' );
}

add_shortcode( 'wp_caption', 'img_caption_shortcode' );
add_shortcode( 'caption', 'img_caption_shortcode' );

/**
 * Builds the Caption shortcode output.
 *
 * Allows a plugin to replace the content that would otherwise be returned. The
 * filter is {@see 'img_caption_shortcode'} and passes an empty string, the attr
 * parameter and the content parameter values.
 *
 * The supported attributes for the shortcode are 'id', 'caption_id', 'align',
 * 'width', 'caption', and 'class'.
 *
 * @since 2.6.0
 * @since 3.9.0 The `class` attribute was added.
 * @since 5.1.0 The `caption_id` attribute was added.
 *
 * @param array  $attr {
 *     Attributes of the caption shortcode.
 *
 *     @type string $id         ID of the image and caption container element, i.e. `<figure>` or `<div>`.
 *     @type string $caption_id ID of the caption element, i.e. `<figcaption>` or `<p>`.
 *     @type string $align      Class name that aligns the caption. Default 'alignnone'. Accepts 'alignleft',
 *                              'aligncenter', alignright', 'alignnone'.
 *     @type int    $width      The width of the caption, in pixels.
 *     @type string $caption    The caption text.
 *     @type string $class      Additional class name(s) added to the caption container.
 * }
 * @param string $content Shortcode content.
 * @return string HTML content to display the caption.
 */
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 ( ! empty( $output ) ) {
		return $output;
	}

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

	$atts['width'] = (int) $atts['width'];

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

	$id          = '';
	$caption_id  = '';
	$describedby = '';

	if ( $atts['id'] ) {
		$atts['id'] = sanitize_html_class( $atts['id'] );
		$id         = 'id="' . esc_attr( $atts['id'] ) . '" ';
	}

	if ( $atts['caption_id'] ) {
		$atts['caption_id'] = sanitize_html_class( $atts['caption_id'] );
	} elseif ( $atts['id'] ) {
		$atts['caption_id'] = 'caption-' . str_replace( '_', '-', $atts['id'] );
	}

	if ( $atts['caption_id'] ) {
		$caption_id  = 'id="' . esc_attr( $atts['caption_id'] ) . '" ';
		$describedby = 'aria-describedby="' . esc_attr( $atts['caption_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 = '';