Where is Featured Image code stored in WP?

Question

Well, I'm looking for source code of these two small containers (PHP backend, HTML frontend & JS used to attach the image):

I want to build a theme option based on Featured Image code, but I'm not able to find it. I'm pretty sure it is somewhere in wp-admin directory, but I've spent loong time there and found nothing.

Any clues?

Answer 1

Markup of that metabox is generated by _wp_post_thumbnail_html() function, contained in wp-admin/includes/post.php.

Answer 2

Some handy links for you:

• http://codex.wordpress.org/Post_Thumbnails
• http://codex.wordpress.org/Function_Reference/get_the_post_thumbnail
• http://codex.wordpress.org/Function_Reference/the_post_thumbnail
• http://codex.wordpress.org/Function_Reference/has_post_thumbnail

Those are useful if you're wanting to display or act differently in the theme, based on the featured image.