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.
Built from https://develop.svn.wordpress.org/trunk@46066


git-svn-id: http://core.svn.wordpress.org/trunk@45878 1a063a9b-81f0-0310-95a4-ce76da25c4cd

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 );

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 );
+}

wp-includes/version.php

@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.3-alpha-46028';
+$wp_version = '5.3-alpha-46066';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.