Eliminate emoji handling altogether since most browsers now support natively

Author: westonruter

includes/class-amp-theme-support.php

@@ -849,19 +849,14 @@ public static function add_hooks() {
 		remove_action( 'wp_head', 'wp_post_preview_js', 1 ); // @todo Instead of function, the script output by wp_post_preview_js() should get data-ampdevmode.
 		remove_action( 'wp_head', 'wp_oembed_add_host_js' ); // This is not needed when post embeds are embedded via <amp-wordpress-embed>. See <https://github.com/ampproject/amp-wp/issues/809>.
 
-		// Replace JS-based emoji with PHP-based, if the JS-based emoji replacement was not already removed.
-		if ( has_action( 'wp_head', 'print_emoji_detection_script' ) ) {
-			remove_action( 'wp_head', 'print_emoji_detection_script', 7 );
-			remove_action( 'wp_print_styles', 'print_emoji_styles' );
-			remove_action( 'wp_footer', 'gutenberg_the_skip_link' ); // Temporary workaround for <https://github.com/ampproject/amp-wp/issues/6115>.
-			remove_action( 'wp_footer', 'the_block_template_skip_link' ); // Temporary workaround for <https://github.com/ampproject/amp-wp/issues/6115>.
-			add_action( 'wp_print_styles', [ __CLASS__, 'print_emoji_styles' ] );
-			add_filter( 'the_title', 'wp_staticize_emoji' );
-			add_filter( 'the_excerpt', 'wp_staticize_emoji' );
-			add_filter( 'the_content', 'wp_staticize_emoji' );
-			add_filter( 'comment_text', 'wp_staticize_emoji' );
-			add_filter( 'widget_text', 'wp_staticize_emoji' );
-		}
+		// Prevent emoji detection and emoji loading since platforms/browsers now support emoji natively (and Twemoji is not AMP-compatible).
+		add_filter( 'wp_resource_hints', [ __CLASS__, 'filter_resource_hints_to_remove_emoji_dns_prefetch' ], 10, 2 );
+		remove_action( 'wp_head', 'print_emoji_detection_script', 7 );
+		remove_action( 'wp_print_styles', 'print_emoji_styles' );
+
+		// Temporary workarounds for <https://github.com/ampproject/amp-wp/issues/6115>.
+		remove_action( 'wp_footer', 'gutenberg_the_skip_link' );
+		remove_action( 'wp_footer', 'the_block_template_skip_link' );
 
 		// @todo The wp_mediaelement_fallback() should still run to be injected inside of the audio/video generated by wp_audio_shortcode()/wp_video_shortcode() respectively.
 		// @todo When custom scripts appear on the page, this logic should be skipped. So the removal of MediaElement.js script & styles should perhaps be done by the script sanitizer instead.
@@ -916,6 +911,28 @@ static function() {
 		);
 	}
 
+	/**
+	 * Filter resource hints to remove the emoji CDN (s.w.org).
+	 *
+	 * @since 2.2
+	 * @see wp_resource_hints()
+	 *
+	 * @param string[] $urls URLs.
+	 * @param string   $type Resource hint relation.
+	 * @return string[] Filtered URLs.
+	 */
+	public static function filter_resource_hints_to_remove_emoji_dns_prefetch( $urls, $type ) {
+		if ( 'dns-prefetch' === $type ) {
+			$urls = array_filter(
+				$urls,
+				static function ( $url ) {
+					return 's.w.org' !== wp_parse_url( $url, PHP_URL_HOST );
+				}
+			);
+		}
+		return $urls;
+	}
+
 	/**
 	 * Register/override widgets.
 	 *
@@ -2246,10 +2263,13 @@ public static function enqueue_assets() {
 	/**
 	 * Print the important emoji-related styles.
 	 *
+	 * @deprecated No longer used since platforms/browsers now support emoji natively. See <https://core.trac.wordpress.org/ticket/35498#comment:7>.
+	 * @codeCoverageIgnore
 	 * @see print_emoji_styles()
 	 * @staticvar bool $printed
 	 */
 	public static function print_emoji_styles() {
+		_deprecated_function( __FUNCTION__, '2.2.0' );
 		static $printed = false;
 
 		if ( $printed ) {

tests/php/test-class-amp-theme-support.php

@@ -775,14 +775,9 @@ public function test_add_hooks() {
 		$this->assertFalse( has_action( 'wp_head', 'wp_post_preview_js' ) );
 		$this->assertFalse( has_action( 'wp_head', 'wp_oembed_add_host_js' ) );
 
+		$this->assertEquals( 10, has_filter( 'wp_resource_hints', [ self::TESTED_CLASS, 'filter_resource_hints_to_remove_emoji_dns_prefetch' ] ) );
 		$this->assertFalse( has_action( 'wp_head', 'print_emoji_detection_script' ) );
 		$this->assertFalse( has_action( 'wp_print_styles', 'print_emoji_styles' ) );
-		$this->assertEquals( 10, has_action( 'wp_print_styles', [ AMP_Theme_Support::class, 'print_emoji_styles' ] ) );
-		$this->assertEquals( 10, has_filter( 'the_title', 'wp_staticize_emoji' ) );
-		$this->assertEquals( 10, has_filter( 'the_excerpt', 'wp_staticize_emoji' ) );
-		$this->assertEquals( 10, has_filter( 'the_content', 'wp_staticize_emoji' ) );
-		$this->assertEquals( 10, has_filter( 'comment_text', 'wp_staticize_emoji' ) );
-		$this->assertEquals( 10, has_filter( 'widget_text', 'wp_staticize_emoji' ) );
 
 		$this->assertEquals( 20, has_action( 'wp_head', 'amp_add_generator_metadata' ) );
 		$this->assertEquals( 0, has_action( 'wp_enqueue_scripts', [ self::TESTED_CLASS, 'enqueue_assets' ] ) );
@@ -797,6 +792,28 @@ public function test_add_hooks() {
 		$this->assertEquals( PHP_INT_MAX, has_filter( 'get_header_image_tag', [ self::TESTED_CLASS, 'amend_header_image_with_video_header' ] ) );
 	}
 
+	/** @covers AMP_Theme_Support::filter_resource_hints_to_remove_emoji_dns_prefetch() */
+	public function test_filter_resource_hints_to_remove_emoji_dns_prefetch() {
+		$hints = [
+			'preconnect'   => [
+				'https://example.com/',
+			],
+			'dns-prefetch' => [
+				'https://example.prg/',
+				apply_filters( 'emoji_svg_url', 'https://s.w.org/images/core/emoji/13.0.0/svg/' ),
+			],
+		];
+
+		$filtered_hints = [];
+		foreach ( $hints as $rel => $urls ) {
+			$filtered_hints[ $rel ] = AMP_Theme_Support::filter_resource_hints_to_remove_emoji_dns_prefetch( $urls, $rel );
+		}
+
+		$this->assertEquals( $hints['preconnect'], $filtered_hints['preconnect'] );
+		$this->assertNotEquals( $hints['dns-prefetch'], $filtered_hints['dns-prefetch'] );
+		$this->assertEquals( [ 'https://example.prg/' ], $filtered_hints['dns-prefetch'] );
+	}
+
 	/**
 	 * Test register_content_embed_handlers.
 	 *