Changeset 55318

Timestamp:

02/13/2023 06:32:40 PM (4 years ago)

Author:

flixos90

Message:

Media: Enhance logic to determine LCP image in block themes and avoid lazy-loading it.

[52065] originally introduced the logic to guess the LCP image based on certain heuristics and to not lazy-load that image. However, with the introduction of block themes, that logic was not functioning correctly, resulting in all featured images to be lazy-loaded, regardless of whether it was the LCP image or not.

Together with an update to the core/post-featured-image block included in [55079], this changeset fixes the logic to correctly handle featured images in block themes as well.

Additionally, in combination with an update to the core/template-part block from [55246], this changeset includes an enhancement which uses the benefits of block template parts to avoid lazy-loading images in the header block template part, making the lazy-loading heuristics even more accurate for sites using a block theme.

Props flixos90, adamsilverstein, mamaduka, antonvlasenko, shahidul95, reduanmasud, costdev, mukesh27, ironprogrammer, manfcarlo, robinwpdeveloper, spacedmonkey.
Fixes #56930.

Location:

trunk

Files:

• src/wp-includes/block-template.php (modified) (1 diff)
• src/wp-includes/media.php (modified) (1 diff)
• tests/phpunit/tests/media.php (modified) (3 diffs)

trunk/src/wp-includes/block-template.php

@@ -242 +242 @@
         $content = convert_smilies( $content );
         $content = shortcode_unautop( $content );
-        $content = wp_filter_content_tags( $content );
+        $content = wp_filter_content_tags( $content, 'template' );
         $content = do_shortcode( $content );
         $content = str_replace( ']]>', ']]>', $content );

trunk/src/wp-includes/media.php

@@ -5445 +5445 @@
  */
 function wp_get_loading_attr_default( $context ) {
-        // Only elements with 'the_content' or 'the_post_thumbnail' context have special handling.
-        if ( 'the_content' !== $context && 'the_post_thumbnail' !== $context ) {
+        // Skip lazy-loading for the overall block template, as it is handled more granularly.
+        if ( 'template' === $context ) {
+                return false;
+        }
+
+        // Do not lazy-load images in the header block template part, as they are likely above the fold.
+        $header_area = WP_TEMPLATE_PART_AREA_HEADER;
+        if ( "template_part_{$header_area}" === $context ) {
+                return false;
+        }
+
+        /*
+         * The first elements in 'the_content' or 'the_post_thumbnail' should not be lazy-loaded,
+         * as they are likely above the fold.
+         */
+        if ( 'the_content' === $context || 'the_post_thumbnail' === $context ) {
+                // Only elements within the main query loop have special handling.
+                if ( is_admin() || ! in_the_loop() || ! is_main_query() ) {
+                        return 'lazy';
+                }
+
+                // Increase the counter since this is a main query content element.
+                $content_media_count = wp_increase_content_media_count();
+
+                // If the count so far is below the threshold, return `false` so that the `loading` attribute is omitted.
+                if ( $content_media_count <= wp_omit_loading_attr_threshold() ) {
+                        return false;
+                }
+
+                // For elements after the threshold, lazy-load them as usual.
                 return 'lazy';
         }
 
-        // Only elements within the main query loop have special handling.
-        if ( is_admin() || ! in_the_loop() || ! is_main_query() ) {
-                return 'lazy';
-        }
-
-        // Increase the counter since this is a main query content element.
-        $content_media_count = wp_increase_content_media_count();
-
-        // If the count so far is below the threshold, return `false` so that the `loading` attribute is omitted.
-        if ( $content_media_count <= wp_omit_loading_attr_threshold() ) {
-                return false;
-        }
-
-        // For elements after the threshold, lazy-load them as usual.
+        // Lazy-load by default for any unknown context.
         return 'lazy';
 }

trunk/tests/phpunit/tests/media.php

@@ -3548 +3548 @@
 
         /**
+         * Tests that wp_get_loading_attr_default() returns the expected loading attribute value.
+         *
          * @ticket 53675
+         * @ticket 56930
+         *
+         * @covers ::wp_get_loading_attr_default
+         *
          * @dataProvider data_wp_get_loading_attr_default
          *
@@ -3589 +3595 @@
                         $this->assertSame( 'lazy', wp_get_loading_attr_default( $context ) );
                 }
+
+                // Exceptions: In the following contexts, images shouldn't be lazy-loaded by default.
+                $this->assertFalse( wp_get_loading_attr_default( 'template' ), 'Images run through the overall block template filter should not be lazy-loaded.' );
+                $this->assertFalse( wp_get_loading_attr_default( 'template_part_' . WP_TEMPLATE_PART_AREA_HEADER ), 'Images in the footer block template part should not be lazy-loaded.' );
         }
 
@@ -3701 +3711 @@
         }
 
+        /**
+         * Tests that wp_filter_content_tags() does not add loading="lazy" to the first
+         * image in the loop when using a block theme.
+         *
+         * @ticket 56930
+         *
+         * @covers ::wp_filter_content_tags
+         * @covers ::wp_get_loading_attr_default
+         */
+        public function test_wp_filter_content_tags_does_not_lazy_load_first_image_in_block_theme() {
+                global $_wp_current_template_content, $wp_query, $wp_the_query, $post;
+
+                // Do not add srcset, sizes, or decoding attributes as they are irrelevant for this test.
+                add_filter( 'wp_img_tag_add_srcset_and_sizes_attr', '__return_false' );
+                add_filter( 'wp_img_tag_add_decoding_attr', '__return_false' );
+
+                $img1      = get_image_tag( self::$large_id, '', '', '', 'large' );
+                $img2      = get_image_tag( self::$large_id, '', '', '', 'medium' );
+                $lazy_img2 = wp_img_tag_add_loading_attr( $img2, 'the_content' );
+
+                // Only the second image should be lazy-loaded.
+                $post_content     = $img1 . $img2;
+                $expected_content = wpautop( $img1 . $lazy_img2 );
+
+                // Update the post to test with so that it has the above post content.
+                wp_update_post(
+                        array(
+                                'ID'                    => self::$post_ids['publish'],
+                                'post_content'          => $post_content,
+                                'post_content_filtered' => $post_content,
+                        )
+                );
+
+                $wp_query     = new WP_Query( array( 'p' => self::$post_ids['publish'] ) );
+                $wp_the_query = $wp_query;
+                $post         = get_post( self::$post_ids['publish'] );
+                $this->reset_content_media_count();
+                $this->reset_omit_loading_attr_filter();
+
+                $_wp_current_template_content = '<!-- wp:post-content /-->';
+
+                $html = get_the_block_template_html();
+                $this->assertSame( '<div class="wp-site-blocks"><div class="entry-content wp-block-post-content is-layout-flow">' . $expected_content . '</div></div>', $html );
+        }
+
+        /**
+         * Tests that wp_filter_content_tags() does not add loading="lazy"
+         * to the featured image when using a block theme.
+         *
+         * @ticket 56930
+         *
+         * @covers ::wp_filter_content_tags
+         * @covers ::wp_get_loading_attr_default
+         */
+        public function test_wp_filter_content_tags_does_not_lazy_load_first_featured_image_in_block_theme() {
+                global $_wp_current_template_content, $wp_query, $wp_the_query, $post;
+
+                // Do not add srcset, sizes, or decoding attributes as they are irrelevant for this test.
+                add_filter( 'wp_img_tag_add_srcset_and_sizes_attr', '__return_false' );
+                add_filter( 'wp_img_tag_add_decoding_attr', '__return_false' );
+                add_filter(
+                        'wp_get_attachment_image_attributes',
+                        function( $attr ) {
+                                unset( $attr['srcset'], $attr['sizes'], $attr['decoding'] );
+                                return $attr;
+                        }
+                );
+
+                $content_img      = get_image_tag( self::$large_id, '', '', '', 'large' );
+                $lazy_content_img = wp_img_tag_add_loading_attr( $content_img, 'the_content' );
+
+                // The featured image should not be lazy-loaded as it is the first image.
+                $featured_image_id = self::$large_id;
+                update_post_meta( self::$post_ids['publish'], '_thumbnail_id', $featured_image_id );
+                $expected_featured_image = '<figure class="wp-block-post-featured-image">' . get_the_post_thumbnail( self::$post_ids['publish'], 'post-thumbnail', array( 'loading' => false ) ) . '</figure>';
+
+                // The post content image should be lazy-loaded since the featured image appears above.
+                $post_content     = $content_img;
+                $expected_content = wpautop( $lazy_content_img );
+
+                // Update the post to test with so that it has the above post content.
+                wp_update_post(
+                        array(
+                                'ID'                    => self::$post_ids['publish'],
+                                'post_content'          => $post_content,
+                                'post_content_filtered' => $post_content,
+                        )
+                );
+
+                $wp_query     = new WP_Query( array( 'p' => self::$post_ids['publish'] ) );
+                $wp_the_query = $wp_query;
+                $post         = get_post( self::$post_ids['publish'] );
+                $this->reset_content_media_count();
+                $this->reset_omit_loading_attr_filter();
+
+                $_wp_current_template_content = '<!-- wp:post-featured-image /--> <!-- wp:post-content /-->';
+
+                $html = get_the_block_template_html();
+                $this->assertSame( '<div class="wp-site-blocks">' . $expected_featured_image . ' <div class="entry-content wp-block-post-content is-layout-flow">' . $expected_content . '</div></div>', $html );
+        }
+
+        /**
+         * Tests that wp_filter_content_tags() does not add loading="lazy" to images
+         * in a "Header" template part.
+         *
+         * @ticket 56930
+         *
+         * @covers ::wp_filter_content_tags
+         * @covers ::wp_get_loading_attr_default
+         */
+        public function test_wp_filter_content_tags_does_not_lazy_load_images_in_header() {
+                global $_wp_current_template_content;
+
+                // Do not add srcset, sizes, or decoding attributes as they are irrelevant for this test.
+                add_filter( 'wp_img_tag_add_srcset_and_sizes_attr', '__return_false' );
+                add_filter( 'wp_img_tag_add_decoding_attr', '__return_false' );
+
+                // Use a single image for each header and footer template parts.
+                $header_img = get_image_tag( self::$large_id, '', '', '', 'large' );
+                $footer_img = get_image_tag( self::$large_id, '', '', '', 'medium' );
+
+                // Create header and footer template parts.
+                $header_post_id = self::factory()->post->create(
+                        array(
+                                'post_type'    => 'wp_template_part',
+                                'post_status'  => 'publish',
+                                'post_name'    => 'header',
+                                'post_content' => $header_img,
+                        )
+                );
+                wp_set_post_terms( $header_post_id, WP_TEMPLATE_PART_AREA_HEADER, 'wp_template_part_area' );
+                wp_set_post_terms( $header_post_id, get_stylesheet(), 'wp_theme' );
+                $footer_post_id = self::factory()->post->create(
+                        array(
+                                'post_type'    => 'wp_template_part',
+                                'post_status'  => 'publish',
+                                'post_name'    => 'footer',
+                                'post_content' => $footer_img,
+                        )
+                );
+                wp_set_post_terms( $footer_post_id, WP_TEMPLATE_PART_AREA_FOOTER, 'wp_template_part_area' );
+                wp_set_post_terms( $footer_post_id, get_stylesheet(), 'wp_theme' );
+
+                $_wp_current_template_content = '<!-- wp:template-part {"slug":"header","theme":"' . get_stylesheet() . '","tagName":"header"} /--><!-- wp:template-part {"slug":"footer","theme":"' . get_stylesheet() . '","tagName":"footer"} /-->';
+
+                // Header image should not be lazy-loaded, footer image should be lazy-loaded.
+                $expected_template_content  = '<header class="wp-block-template-part">' . $header_img . '</header>';
+                $expected_template_content .= '<footer class="wp-block-template-part">' . wp_img_tag_add_loading_attr( $footer_img, 'force-lazy' ) . '</footer>';
+
+                $html = get_the_block_template_html();
+                $this->assertSame( '<div class="wp-site-blocks">' . $expected_template_content . '</div>', $html );
+        }
+
         private function reset_content_media_count() {
                 // Get current value without increasing.