* API for easily embedding rich media such as videos and images into content.
public $handlers = array();
public $linkifunknown = true;
public $last_attr = array();
* When a URL cannot be embedded, return false instead of returning a link
* Bypasses the {@see 'embed_maybe_make_link'} filter.
public $return_false_on_fail = false;
public function __construct() {
// Hack to get the [embed] shortcode to run before wpautop().
add_filter( 'the_content', array( $this, 'run_shortcode' ), 8 );
add_filter( 'widget_text_content', array( $this, 'run_shortcode' ), 8 );
// Shortcode placeholder for strip_shortcodes().
add_shortcode( 'embed', '__return_false' );
// Attempts to embed all URLs in a post.
add_filter( 'the_content', array( $this, 'autoembed' ), 8 );
add_filter( 'widget_text_content', array( $this, 'autoembed' ), 8 );
// After a post is saved, cache oEmbed items via Ajax.
add_action( 'edit_form_advanced', array( $this, 'maybe_run_ajax_cache' ) );
add_action( 'edit_page_form', array( $this, 'maybe_run_ajax_cache' ) );
* Process the [embed] shortcode.
* Since the [embed] shortcode needs to be run earlier than other shortcodes,
* this function removes all existing shortcodes, registers the [embed] shortcode,
* calls do_shortcode(), and then re-registers the old shortcodes.
* @global array $shortcode_tags
* @param string $content Content to parse
* @return string Content with shortcode parsed
public function run_shortcode( $content ) {
// Back up current registered shortcodes and clear them all out.
$orig_shortcode_tags = $shortcode_tags;
add_shortcode( 'embed', array( $this, 'shortcode' ) );
// Do the shortcode (only the [embed] one is registered).
$content = do_shortcode( $content, true );
// Put the original shortcodes back.
$shortcode_tags = $orig_shortcode_tags;
* If a post/page was saved, then output JavaScript to make
* an Ajax request that will call WP_Embed::cache_oembed().
public function maybe_run_ajax_cache() {
if ( ! $post || empty( $_GET['message'] ) ) {
<script type="text/javascript">
jQuery(document).ready(function($){
$.get("<?php echo admin_url( 'admin-ajax.php?action=oembed-cache&post=' . $post->ID, 'relative' ); ?>");
* Registers an embed handler.
* Do not use this function directly, use wp_embed_register_handler() instead.
* This function should probably also only be used for sites that do not support oEmbed.
* @param string $id An internal ID/name for the handler. Needs to be unique.
* @param string $regex The regex that will be used to see if this handler should be used for a URL.
* @param callable $callback The callback function that will be called if the regex is matched.
* @param int $priority Optional. Used to specify the order in which the registered handlers will be tested.
* Lower numbers correspond with earlier testing, and handlers with the same priority are
* tested in the order in which they were added to the action. Default 10.
public function register_handler( $id, $regex, $callback, $priority = 10 ) {
$this->handlers[ $priority ][ $id ] = array(
* Unregisters a previously-registered embed handler.
* Do not use this function directly, use wp_embed_unregister_handler() instead.
* @param string $id The handler ID that should be removed.
* @param int $priority Optional. The priority of the handler to be removed (default: 10).
public function unregister_handler( $id, $priority = 10 ) {
unset( $this->handlers[ $priority ][ $id ] );
* Returns embed HTML for a given URL from embed handlers.
* Attempts to convert a URL into embed HTML by checking the URL
* against the regex of the registered embed handlers.
* Shortcode attributes. Optional.
* @type int $width Width of the embed in pixels.
* @type int $height Height of the embed in pixels.
* @param string $url The URL attempting to be embedded.
* @return string|false The embed HTML on success, false otherwise.
public function get_embed_handler_html( $attr, $url ) {
$attr = wp_parse_args( $attr, wp_embed_defaults( $url ) );
ksort( $this->handlers );
foreach ( $this->handlers as $priority => $handlers ) {
foreach ( $handlers as $id => $handler ) {
if ( preg_match( $handler['regex'], $url, $matches ) && is_callable( $handler['callback'] ) ) {
$return = call_user_func( $handler['callback'], $matches, $attr, $url, $rawattr );
if ( false !== $return ) {
* Filters the returned embed HTML.
* @see WP_Embed::shortcode()
* @param string|false $return The HTML result of the shortcode, or false on failure.
* @param string $url The embed URL.
* @param array $attr An array of shortcode attributes.
return apply_filters( 'embed_handler_html', $return, $url, $attr );
* The do_shortcode() callback function.
* Attempts to convert a URL into embed HTML. Starts by checking the URL against the regex of
* the registered embed handlers. If none of the regex matches and it's enabled, then the URL
* will be given to the WP_oEmbed class.
* Shortcode attributes. Optional.
* @type int $width Width of the embed in pixels.
* @type int $height Height of the embed in pixels.
* @param string $url The URL attempting to be embedded.
* @return string|false The embed HTML on success, otherwise the original URL.
* `->maybe_make_link()` can return false on failure.
public function shortcode( $attr, $url = '' ) {
if ( empty( $url ) && ! empty( $attr['src'] ) ) {
$this->last_attr = $attr;
$attr = wp_parse_args( $attr, wp_embed_defaults( $url ) );
$this->last_attr = $attr;
// KSES converts & into & and we need to undo this.
// See https://core.trac.wordpress.org/ticket/11311
$url = str_replace( '&', '&', $url );
// Look for known internal handlers.
$embed_handler_html = $this->get_embed_handler_html( $rawattr, $url );
if ( false !== $embed_handler_html ) {
return $embed_handler_html;
$post_ID = ( ! empty( $post->ID ) ) ? $post->ID : null;
// Potentially set by WP_Embed::cache_oembed().
if ( ! empty( $this->post_ID ) ) {
$post_ID = $this->post_ID;
// Check for a cached result (stored as custom post or in the post meta).
$key_suffix = md5( $url . serialize( $attr ) );
$cachekey = '_oembed_' . $key_suffix;
$cachekey_time = '_oembed_time_' . $key_suffix;
* Filters the oEmbed TTL value (time to live).
* @param int $time Time to live (in seconds).
* @param string $url The attempted embed URL.
* @param array $attr An array of shortcode attributes.
* @param int $post_ID Post ID.
$ttl = apply_filters( 'oembed_ttl', DAY_IN_SECONDS, $url, $attr, $post_ID );
$cached_post_id = $this->find_oembed_post_id( $key_suffix );
$cache = get_post_meta( $post_ID, $cachekey, true );
$cache_time = get_post_meta( $post_ID, $cachekey_time, true );
} elseif ( $cached_post_id ) {
$cached_post = get_post( $cached_post_id );
$cache = $cached_post->post_content;
$cache_time = strtotime( $cached_post->post_modified_gmt );
$cached_recently = ( time() - $cache_time ) < $ttl;
if ( $this->usecache || $cached_recently ) {
// Failures are cached. Serve one if we're using the cache.
if ( '{{unknown}}' === $cache ) {
return $this->maybe_make_link( $url );
if ( ! empty( $cache ) ) {
* Filters the cached oEmbed HTML.
* @see WP_Embed::shortcode()
* @param string|false $cache The cached HTML result, stored in post meta.
* @param string $url The attempted embed URL.
* @param array $attr An array of shortcode attributes.
* @param int $post_ID Post ID.
return apply_filters( 'embed_oembed_html', $cache, $url, $attr, $post_ID );
* Filters whether to inspect the given URL for discoverable link tags.
* @since 4.4.0 The default value changed to true.
* @see WP_oEmbed::discover()
* @param bool $enable Whether to enable `<link>` tag discovery. Default true.
$attr['discover'] = apply_filters( 'embed_oembed_discover', true );
// Use oEmbed to get the HTML.
$html = wp_oembed_get( $url, $attr );
update_post_meta( $post_ID, $cachekey, $html );
update_post_meta( $post_ID, $cachekey_time, time() );
update_post_meta( $post_ID, $cachekey, '{{unknown}}' );
$has_kses = false !== has_filter( 'content_save_pre', 'wp_filter_post_kses' );
// Prevent KSES from corrupting JSON in post_content.
$insert_post_args = array(
'post_name' => $key_suffix,
'post_status' => 'publish',
'post_type' => 'oembed_cache',
'post_content' => '{{unknown}}',
// If there was a result, return it.
/** This filter is documented in wp-includes/class-wp-embed.php */
return apply_filters( 'embed_oembed_html', $html, $url, $attr, $post_ID );
return $this->maybe_make_link( $url );
* Delete all oEmbed caches. Unused by core as of 4.0.0.
* @param int $post_ID Post ID to delete the caches for.
public function delete_oembed_caches( $post_ID ) {
$post_metas = get_post_custom_keys( $post_ID );
if ( empty( $post_metas ) ) {
foreach ( $post_metas as $post_meta_key ) {
if ( '_oembed_' === substr( $post_meta_key, 0, 8 ) ) {
delete_post_meta( $post_ID, $post_meta_key );
* Triggers a caching of all oEmbed results.
* @param int $post_ID Post ID to do the caching for.
public function cache_oembed( $post_ID ) {
$post = get_post( $post_ID );
$post_types = get_post_types( array( 'show_ui' => true ) );
* Filters the array of post types to cache oEmbed results for.
* @param string[] $post_types Array of post type names to cache oEmbed results for. Defaults to post types with `show_ui` set to true.
$cache_oembed_types = apply_filters( 'embed_cache_oembed_types', $post_types );
if ( empty( $post->ID ) || ! in_array( $post->post_type, $cache_oembed_types, true ) ) {
if ( ! empty( $post->post_content ) ) {
$this->post_ID = $post->ID;
$content = $this->run_shortcode( $post->post_content );
$this->autoembed( $content );
* Passes any unlinked URLs that are on their own line to WP_Embed::shortcode() for potential embedding.
* @see WP_Embed::autoembed_callback()
* @param string $content The content to be searched.
* @return string Potentially modified $content.
public function autoembed( $content ) {
// Replace line breaks from all HTML elements with placeholders.
$content = wp_replace_in_html_tags( $content, array( "\n" => '<!-- wp-line-break -->' ) );
if ( preg_match( '#(^|\s|>)https?://#i', $content ) ) {
// Find URLs on their own line.
$content = preg_replace_callback( '|^(\s*)(https?://[^\s<>"]+)(\s*)$|im', array( $this, 'autoembed_callback' ), $content );
// Find URLs in their own paragraph.
$content = preg_replace_callback( '|(<p(?: [^>]*)?>\s*)(https?://[^\s<>"]+)(\s*<\/p>)|i', array( $this, 'autoembed_callback' ), $content );
// Put the line breaks back.
return str_replace( '<!-- wp-line-break -->', "\n", $content );
* Callback function for WP_Embed::autoembed().
* @param array $match A regex match array.
* @return string The embed HTML on success, otherwise the original URL.
public function autoembed_callback( $match ) {
$oldval = $this->linkifunknown;
$this->linkifunknown = false;
$return = $this->shortcode( array(), $match[2] );
$this->linkifunknown = $oldval;
return $match[1] . $return . $match[3];
* Conditionally makes a hyperlink based on an internal class variable.
* @param string $url URL to potentially be linked.
* @return string|false Linked URL or the original URL. False if 'return_false_on_fail' is true.
public function maybe_make_link( $url ) {
if ( $this->return_false_on_fail ) {
$output = ( $this->linkifunknown ) ? '<a href="' . esc_url( $url ) . '">' . esc_html( $url ) . '</a>' : $url;
* Filters the returned, maybe-linked embed URL.
* @param string $output The linked or original URL.
* @param string $url The original URL.
return apply_filters( 'embed_maybe_make_link', $output, $url );
* Find the oEmbed cache post ID for a given cache key.
* @param string $cache_key oEmbed cache key.
* @return int|null Post ID on success, null on failure.
public function find_oembed_post_id( $cache_key ) {
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