Embeds in new text widget

[samikeijonen]

Should embeds work in new text widget in the same way as in post?

For example youtube link in it's own line would show the video.

[westonruter]

Ideally yes, but we cannot currently process embeds in the content due to embeds requiring a post context due to the need to cache in postmeta. If we do support embeds we'd have to limit to those which are handled internally, not any that requiring external requests (and this caching).

[westonruter]

A proof of concept to allow embeds:

diff --git a/wp-includes/widgets/class-wp-widget-visual-text.php b/wp-includes/widgets/class-wp-widget-visual-text.php
index 8509aea..077b57a 100644
--- a/wp-includes/widgets/class-wp-widget-visual-text.php
+++ b/wp-includes/widgets/class-wp-widget-visual-text.php
@@ -64,6 +64,22 @@ class WP_Widget_Visual_Text extends WP_Widget_Text {
 		if ( isset( $instance['filter'] ) ) {
 			if ( 'content' === $instance['filter'] ) {
 
+				add_filter( 'embed_oembed_discover', '__return_false', 100 );
+
+				/**
+				 * @var WP_Embed $wp_embed
+				 */
+				global $wp_embed;
+
+				$using_cache = $wp_embed->usecache;
+				$wp_embed->usecache = false;
+
+				// Hack to get the [embed] shortcode to run before wpautop()
+				add_filter( 'widget_text_content', array( $wp_embed, 'run_shortcode' ), 8 );
+
+				// Attempts to embed all URLs in a post
+				add_filter( 'widget_text_content', array( $wp_embed, 'autoembed' ), 8 );
+
 				/**
 				 * Filters the content of the Text widget to apply changes expected from the visual (TinyMCE) editor.
 				 *
@@ -75,7 +91,12 @@ class WP_Widget_Visual_Text extends WP_Widget_Text {
 				 * @param array          $instance    Array of settings for the current widget.
 				 * @param WP_Widget_Text $this        Current Text widget instance.
 				 */
-				$text = apply_filters( 'widget_text_content', $widget_text, $instance, $this );
+				$text = apply_filters( 'widget_text_content', $text, $instance, $this );
+
+				remove_filter( 'widget_text_content', array( $wp_embed, 'autoembed' ), 8 );
+				remove_filter( 'widget_text_content', array( $wp_embed, 'run_shortcode' ), 8 );
+				remove_filter( 'embed_oembed_discover', '__return_false', 100 );
+				$wp_embed->usecache = $using_cache;
 
 			} elseif ( $instance['filter'] ) {
 				$text = wpautop( $text ); // Back-compat for instances prior to 4.8.

Note that discovery and caching are disabled since postmeta caching cannot be relied upon.

If you try the patch you'll immediately notice a couple things:

1. A YouTube video is embedded according to $content_width which is clearly wrong in the context of a widget sidebar (usually). Some strategies would be needed for getting the width and height to be correct, per Handle height/width for videos #93.
2. TinyMCE isn't recognizing the embeds.