Media: Introduce `wp_content_img_tag` filter.

This filter allows modifying individual `img` tags within a blob of content that are by default processed by the `wp_filter_content_tags()` function. The addition of this filter facilitates plugins that tweak images to accomplish this goal without re-implementing duplicate content image parser logic, which furthermore can have a negative performance impact due to additional regular expressions.

In addition to the filterable `img` tag, the filter receives the context (typically the function or filter in which the content is parsed) and the attachment ID. The latter may be 0, in case the image is not an attachment (for example when it is an external image URL).

Props adamsilverstein, flixos90, pbearne, peterwilsoncc.
Fixes #55347.

Built from https://develop.svn.wordpress.org/trunk@53028


git-svn-id: http://core.svn.wordpress.org/trunk@52617 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/media.php

@@ -1843,6 +1843,17 @@ function wp_filter_content_tags( $content, $context = null ) {
 				$filtered_image = wp_img_tag_add_loading_attr( $filtered_image, $context );
 			}
 
+			/**
+			 * Filters an img tag within the content for a given context.
+			 *
+			 * @since 6.0.0
+			 *
+			 * @param string $filtered_image Full img tag with attributes that will replace the source img tag.
+			 * @param string $context        Additional context, like the current filter name or the function name from where this was called.
+			 * @param int    $attachment_id  The image attachment ID. May be 0 in case the image is not an attachment.
+			 */
+			$filtered_image = apply_filters( 'wp_content_img_tag', $filtered_image, $context, $attachment_id );
+
 			if ( $filtered_image !== $match[0] ) {
 				$content = str_replace( $match[0], $filtered_image, $content );
 			}

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.0-alpha-53027';
+$wp_version = '6.0-alpha-53028';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.