投稿画像リンクにrel=”lightbox”追加滋賀県守山市のホームページ制作

functions.php

add_filter('the_content', 'rellightbox_replace');
function rellightbox_replace ($content){
 global $post;
 $pattern = "/<a(.*?)href=('|\")(.*?).(bmp|gif|jpeg|jpg|png)('|\")(.*?)>/i";
 $replacement = '<a$1href=$2$3.$4$5 rel="lightbox"$6>';
 $content = preg_replace($pattern, $replacement, $content);
 return $content;
}