Ticket #46124: ticket46124.diff

src/wp-includes/theme.php

@@ -1092 +1092 @@
                 )
         );
 
-        // Generate 'srcset' and 'sizes' if not already present.
-        if ( empty( $attr['srcset'] ) && ! empty( $header->attachment_id ) ) {
-                $image_meta = get_post_meta( $header->attachment_id, '_wp_attachment_metadata', true );
-                $size_array = array( $width, $height );
+        if ( ! empty( $header->attachment_id ) ) {
+                // Use actual alt attribute text from the image, if set.
+                // The image URL can be filtered via `get_header_image()` above, so we need to check it before applying the alt text.
+                $image_alt = get_post_meta( $header->attachment_id, '_wp_attachment_image_alt', true );
+                if ( ! empty( $image_alt ) && wp_get_attachment_url( $header->attachment_id ) === $attr['src'] ) {
+                        $attr['alt'] = $image_alt;
+                }
 
-                if ( is_array( $image_meta ) ) {
-                        $srcset = wp_calculate_image_srcset( $size_array, $header->url, $image_meta, $header->attachment_id );
-                        $sizes  = ! empty( $attr['sizes'] ) ? $attr['sizes'] : wp_calculate_image_sizes( $size_array, $header->url, $image_meta, $header->attachment_id );
+                // Generate 'srcset' and 'sizes' if not already present.
+                if ( empty( $attr['srcset'] ) ) {
+                        $image_meta = get_post_meta( $header->attachment_id, '_wp_attachment_metadata', true );
+                        $size_array = array( $width, $height );
 
-                        if ( $srcset && $sizes ) {
-                                $attr['srcset'] = $srcset;
-                                $attr['sizes']  = $sizes;
+                        if ( is_array( $image_meta ) ) {
+                                $srcset = wp_calculate_image_srcset( $size_array, $header->url, $image_meta, $header->attachment_id );
+                                $sizes  = ! empty( $attr['sizes'] ) ? $attr['sizes'] : wp_calculate_image_sizes( $size_array, $header->url, $image_meta, $header->attachment_id );
+
+                                if ( $srcset && $sizes ) {
+                                        $attr['srcset'] = $srcset;
+                                        $attr['sizes']  = $sizes;
+                                }
                         }
                 }
         }