From ebd03692e64d63803ad3fed2676dfb3cd4631f26 Mon Sep 17 00:00:00 2001
From: Felix Arntz <flixos90@git.wordpress.org>
Date: Wed, 5 Jul 2023 21:36:23 +0000
Subject: [PATCH] Media: Ensure that large images before the main query loop
 are counted towards lazy-loading threshold.

Following [55318], [55847], and [56142], certain images in the header of the page have received support for potentially receiving `fetchpriority="high"` and having the `loading="lazy"` attribute omitted. However, these images being present did not affect the "content media count" which counts the images towards a certain threshold so that the first ones are not lazy-loaded.

This changeset also increases that count for such header images if they are larger than a certain threshold. The threshold is used to avoid e.g. a header with lots of small images such as icon graphics to skew the lazy-loading behavior.

Props thekt12, spacedmonkey, flixos90.
Fixes #58635.


git-svn-id: https://develop.svn.wordpress.org/trunk@56143 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/media.php     | 15 +++++++++++
 tests/phpunit/tests/media.php | 49 +++++++++++++++++++++++++++++++++++
 2 files changed, 64 insertions(+)

diff --git a/src/wp-includes/media.php b/src/wp-includes/media.php
index 0da68e3d43..11815e65fa 100644
--- a/src/wp-includes/media.php
+++ b/src/wp-includes/media.php
@@ -5588,6 +5588,15 @@ function wp_get_loading_optimization_attributes( $tag_name, $attr, $context ) {
 		}
 		return $loading_attributes;
 	};
+	// Closure to increase media count for images with certain minimum threshold, mostly used for header images.
+	$maybe_increase_content_media_count = static function() use ( $attr ) {
+		/** This filter is documented in wp-admin/includes/media.php */
+		$wp_min_priority_img_pixels = apply_filters( 'wp_min_priority_img_pixels', 50000 );
+		// Images with a certain minimum size in the header of the page are also counted towards the threshold.
+		if ( $wp_min_priority_img_pixels <= $attr['width'] * $attr['height'] ) {
+			wp_increase_content_media_count();
+		}
+	};
 
 	$loading_attrs = array();
 
@@ -5640,11 +5649,15 @@ function wp_get_loading_optimization_attributes( $tag_name, $attr, $context ) {
 	 */
 	$header_area = WP_TEMPLATE_PART_AREA_HEADER;
 	if ( "template_part_{$header_area}" === $context ) {
+		// Increase media count if there are images in header above a certian minimum size threshold.
+		$maybe_increase_content_media_count();
 		return $postprocess( $loading_attrs, true );
 	}
 
 	// The custom header image is always expected to be in the header.
 	if ( 'get_header_image_tag' === $context ) {
+		// Increase media count if there are images in header above a certian minimum size threshold.
+		$maybe_increase_content_media_count();
 		return $postprocess( $loading_attrs, true );
 	}
 
@@ -5671,6 +5684,8 @@ function wp_get_loading_optimization_attributes( $tag_name, $attr, $context ) {
 			 */
 			&& did_action( 'get_header' ) && ! did_action( 'get_footer' )
 		) {
+			// Increase media count if there are images in header above a certian minimum size threshold.
+			$maybe_increase_content_media_count();
 			return $postprocess( $loading_attrs, true );
 		}
 	}
diff --git a/tests/phpunit/tests/media.php b/tests/phpunit/tests/media.php
index 2fcbe2264f..41c1598a0e 100644
--- a/tests/phpunit/tests/media.php
+++ b/tests/phpunit/tests/media.php
@@ -5094,6 +5094,55 @@ EOF;
 		);
 	}
 
+	/**
+	 * @ticket 58635
+	 *
+	 * @covers ::wp_get_loading_optimization_attributes
+	 */
+	public function test_wp_get_loading_optimization_attributes_header_block_template_increase_media_count() {
+		$attr = $this->get_width_height_for_high_priority();
+		wp_get_loading_optimization_attributes( 'img', $attr, 'template_part_' . WP_TEMPLATE_PART_AREA_HEADER );
+
+		// Images with a certain minimum size in the header of the page are also counted towards the threshold.
+		$this->assertSame( 1, wp_increase_content_media_count( 0 ) );
+	}
+
+	/**
+	 * @ticket 58635
+	 *
+	 * @covers ::wp_get_loading_optimization_attributes
+	 */
+	public function test_wp_get_loading_optimization_attributes_header_image_tag_increase_media_count() {
+		$attr = $this->get_width_height_for_high_priority();
+		wp_get_loading_optimization_attributes( 'img', $attr, 'get_header_image_tag' );
+
+		// Images with a certain minimum size in the header of the page are also counted towards the threshold.
+		$this->assertSame( 1, wp_increase_content_media_count( 0 ) );
+	}
+
+	/**
+	 * @ticket 58635
+	 *
+	 * @covers ::wp_get_loading_optimization_attributes
+	 *
+	 * @dataProvider data_wp_get_loading_attr_default_before_and_no_loop
+	 *
+	 * @param string $context Context for the element for which the `loading` attribute value is requested.
+	 */
+	public function test_wp_get_loading_optimization_attributes_image_before_loop_increase_media_count( $context ) {
+		global $wp_query;
+
+		$wp_query = $this->get_new_wp_query_for_published_post();
+		$this->set_main_query( $wp_query );
+		do_action( 'get_header' );
+
+		$attr = $this->get_width_height_for_high_priority();
+		wp_get_loading_optimization_attributes( 'img', $attr, $context );
+
+		// Images with a certain minimum size in the header of the page are also counted towards the threshold.
+		$this->assertSame( 1, wp_increase_content_media_count( 0 ) );
+	}
+
 	/**
 	 * Helper method to keep track of the last context returned by the 'wp_get_attachment_image_context' filter.
 	 *