From a38ecee8c9554dfd3b6152fc0b1950cd69838fc4 Mon Sep 17 00:00:00 2001
From: Andrew Ozz <azaozz@git.wordpress.org>
Date: Thu, 5 Sep 2019 22:26:50 +0000
Subject: [PATCH] Media: Add two new intermediate image sizes, 1536px and
 2048px. They are meant to enhance the way WordPress displays images on the
 front-end on larger, high-density devices. They make it possible to generate
 more suitable `srcset` and `sizes` attributes, and not use the original,
 often non-optimized image.

Also change the default `max_srcset_image_width` value to match the new max size.

Props pierlo, azaozz.
See #43524.

git-svn-id: https://develop.svn.wordpress.org/trunk@46066 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/default-filters.php |  1 +
 src/wp-includes/media.php           | 24 ++++++++++++++++++++++--
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/src/wp-includes/default-filters.php b/src/wp-includes/default-filters.php
index f88398d0ee..fc0f4408f7 100644
--- a/src/wp-includes/default-filters.php
+++ b/src/wp-includes/default-filters.php
@@ -519,6 +519,7 @@ add_filter( 'the_content', 'do_shortcode', 11 ); // AFTER wpautop()
 // Media
 add_action( 'wp_playlist_scripts', 'wp_playlist_scripts' );
 add_action( 'customize_controls_enqueue_scripts', 'wp_plupload_default_settings' );
+add_action( 'plugins_loaded', '_wp_add_additional_image_sizes', 0 );
 
 // Nav menu
 add_filter( 'nav_menu_item_id', '_nav_menu_item_id_use_once', 10, 2 );
diff --git a/src/wp-includes/media.php b/src/wp-includes/media.php
index b9601c3f60..6f104a20c7 100644
--- a/src/wp-includes/media.php
+++ b/src/wp-includes/media.php
@@ -1200,10 +1200,10 @@ function wp_calculate_image_srcset( $size_array, $image_src, $image_meta, $attac
 	 *
 	 * @since 4.4.0
 	 *
-	 * @param int   $max_width  The maximum image width to be included in the 'srcset'. Default '1600'.
+	 * @param int   $max_width  The maximum image width to be included in the 'srcset'. Default '2048'.
 	 * @param array $size_array Array of width and height values in pixels (in that order).
 	 */
-	$max_srcset_image_width = apply_filters( 'max_srcset_image_width', 1600, $size_array );
+	$max_srcset_image_width = apply_filters( 'max_srcset_image_width', 2048, $size_array );
 
 	// Array to hold URL candidates.
 	$sources = array();
@@ -4329,3 +4329,23 @@ function wp_media_personal_data_exporter( $email_address, $page = 1 ) {
 		'done' => $done,
 	);
 }
+
+/**
+ * Add additional default image sub-sizes.
+ *
+ * These sizes are meant to enhance the way WordPress displays images on the front-end on larger,
+ * high-density devices. They make it possible to generate more suitable `srcset` and `sizes` attributes
+ * when the users upload large images.
+ *
+ * The sizes can be changed or removed by themes and plugins but that is not recommended.
+ * The size "names" reflect the image dimensions, so changing the sizes would be quite misleading.
+ *
+ * @since 5.3.0
+ * @access private
+ */
+function _wp_add_additional_image_sizes() {
+	// 2x medium_large size
+	add_image_size( '1536x1536', 1536, 1536 );
+	// 2x large size
+	add_image_size( '2048x2048', 2048, 2048 );
+}