WP - Post images as a link to next post page - php

Question

I am using wordpress and twenty twelve child as my theme.
I made a website for funny pictures, and basically what I want is the image inside every page to act like a link to a next image. Heres some example sites with this feature: DailyHaHa and Meme-lol.com You see if you click the image, it will take you to next image page. I'm working on local machine so I can't give link to my website. Here is my content.php:
<article id="post-<?php the_ID(); ?>" <?php post_class(); ?>>
<?php if ( is_sticky() && is_home() && ! is_paged() ) : ?>
<div class="featured-post">
<?php _e( 'Featured post', 'twentytwelve' ); ?>
</div>
<?php endif; ?>
<div class="entry-header">
<?php the_post_thumbnail(); ?>
<?php if ( is_single() ) : ?>
<div class="post-header">
<div class="entry-title">
<?php the_title(); ?>
</div>
<span class="inline-div">
<span class="entry-bar"><li><?php echo "Added "; wp_days_ago(); ?></li> </span>
<li><?php comments_popup_link( '<span class="leave-reply">' . __( 'Be first to comment', 'twentytwelve' ) . '</span>', __( '1 comment', 'twentytwelve' ), __( '% comments', 'twentytwelve' ) ); ?></li>
<!-- .comments-link -->
<span class="edit"><li><?php edit_post_link( __( 'Edit', 'twentytwelve' ), '<span class="edit-link">', '</span>' ); ?></li></span>
</span>
<?php else : ?>
<div class="entry-title">
<?php the_title(); ?>
</div>
<span class="inline-div">
<span class="entry-bar"><li><?php echo "Added "; wp_days_ago(); ?></li> </span>
<li><?php comments_popup_link( '<span class="leave-reply">' . __( 'Be first to comment', 'twentytwelve' ) . '</span>', __( '1 comment', 'twentytwelve' ), __( '% comments', 'twentytwelve' ) ); ?></li>
<!-- .comments-link -->
<span class="edit"><li><?php edit_post_link( __( 'Edit', 'twentytwelve' ), '<span class="edit-link">', '</span>' ); ?></li></span>
</span>
<?php endif; // is_single() ?>
</div><!-- .entry-header -->
<?php if ( is_search() ) : // Only display Excerpts for Search ?>
<div class="entry-summary">
<?php the_excerpt(); ?>
</div><!-- .entry-summary -->
<?php else : ?>
<div class="entry-content">
<?php the_content( __( 'Continue reading <span class="meta-nav">→</span>', 'twentytwelve' ) ); ?>
<?php wp_link_pages( array( 'before' => '<div class="page-links">' . __( 'Pages:', 'twentytwelve' ), 'after' => '</div>' ) ); ?>
</div><!-- .entry-content -->
<?php endif; ?>
<div class="share-buttons">
<a class="facebook-button" target="_blank" onclick="return !window.open(this.href, 'Facebook', 'width=640,height=300')" href="http://www.facebook.com/sharer/sharer.php?u=<?php the_permalink(); ?>"><img src="/images/share.png" /></a>
<a class="tweet-button" target="_blank" href="http://twitter.com/share"><img src="/images/tweet.png" /></a>
</div>
<div class="nav2">
<span class="previous-button">
<?php next_post_link( '%link', '<img src="/images/prev.png" alt="Previous"/>' ); ?>
</span>
<span class="random-post">
<?php $randomPost = $wpdb->get_var("SELECT guid FROM $wpdb->posts WHERE post_type = 'post' AND post_status = 'publish' ORDER BY rand() LIMIT 1");
echo '<img src="/images/random.png" alt="Random"/>'; ?>
</span>
<span class="next-button">
<?php previous_post_link( '%link', '<img src="/images/Next.png" alt="Next"/>' ); ?>
</div>
<br />
</span>
</article><!-- #post -->

Answer 1

You need to get the featured image of the post first.
<?php // Display the thumbnail of the previous post ?>
<span class="previous-button"> <?php
$prevPost = get_previous_post();
$prevthumbnail = get_the_post_thumbnail($prevPost->ID); ?>
<?php previous_post_link('%link', $prevthumbnail); ?>
</span>
<?php // Display the thumbnail of the next post ?>
<span class="next-button"> <?php
$nextPost = get_next_post();
$nextthumbnail = get_the_post_thumbnail($nextPost->ID); ?>
<?php next_post_link('%link', $nextthumbnail); ?>
</span>