How to replace header-image with featured-image

Hi,

I have ported the header-image function of twentyeleven for those, who wish to replace the header-image by the featured image (when it’s set) on a singular page.

1. Create a childtheme based on twentytwelve
2. Copy over header.php and replace the following (you might have some additional anchor markup, which I removed)

<?php $header_image = get_header_image();
if ( ! empty( $header_image ) ) : ?>
	<a href="<?php echo esc_url( home_url( '/' ) ); ?>"><img src="<?php echo esc_url( $header_image ); ?>" class="header-image" width="<?php echo get_custom_header()->width; ?>" height="<?php echo get_custom_header()->height; ?>" alt="" /></a>
<?php endif; ?>

with

<?php $header_image = get_header_image();
if ( ! empty( $header_image ) ) : ?>
	<?php
	if ( is_singular() && has_post_thumbnail( $post->ID ) ) :
		echo get_the_post_thumbnail( $post->ID, 'full', 'class=header-image' );
	else : ?>
	<img src="<?php echo esc_url( $header_image ); ?>" class="header-image" width="<?php echo get_custom_header()->width; ?>" height="<?php echo get_custom_header()->height; ?>" alt="" />
	<?php endif; ?>
<?php endif; ?>

3. Copy over content.php and the replace the following (line 18)
<?php the_post_thumbnail(); ?>
with

<?php if ( is_home() ) : ?>
	<?php the_post_thumbnail(); ?>
<?php endif; ?>

The outcome:
https://s7.directupload.net/images/user/121028/temp/vrmnzh2a.jpg

https://s14.directupload.net/images/user/121028/temp/ogfb6b7e.jpg

Info on Step 2: I’ve removed the additional image-size checks of twentyeleven. But they can be easily added.

Step 3 will avoid multiple header-images on singular pages. On the home page, it will show the featured image as a thumbnail.

For some reason, class=”wp-post-image” (besides “header-image”) is also applied to the header. Usually, it doesn’t hurt. But still, are there any workarounds?

Please feel free to improve / minimize / optimize the code!

Have fun ;)!