Wordpress functions.php - if condition kills other posts content - php

Question

So I got this code, which I am trying to adapt to my needs. It should and does wrap a div around the necessary <img> tags. But when I add the "if (is_page...)" all other sites have no content anymore. I am very confused as to why this is happening since the code should not execute or do anything when the if statement is not met.
function breezer_addDivToImage( $content ) {
if ( is_page_template('single.php') ) {
// A regular expression of what to look for.
$pattern = '/(<img([^>]*)>)/i';
// What to replace it with. $1 refers to the content in the first 'capture group', in parentheses above
$replacement = '<div class="myphoto">$1</div>';
// run preg_replace() on the $content
$content = preg_replace( $pattern, $replacement, $content );
// return the processed content
return $content;
}
}
add_filter( 'the_content', 'breezer_addDivToImage' );
/* Place custom code above this line. */
?>
This is how i display the content on the page
<!--S3 show if dynamic page (blogposts)-->
<?php } else if (is_page() == false) {
if(have_posts()) :
while(have_posts()) : the_post();
if ( has_post_thumbnail() ) {
<img class="responsive-img" src="<?php the_post_thumbnail_url(); ?>">
<?php } ?>
<h2><?php the_title(); ?></h2>
<?php the_content();
endwhile;
else : ?>
<h3></h3>
<p></p>
<?php endif;
} ?>
<!--S3 end "show if dynamic page"-->

Answer 1

you filter your content of all pages and posts with this hook and only return the content if the condition is true.
Put simply a else {return $content} to your breezer_addDivToImage function.
function breezer_addDivToImage( $content ) {
if ( is_page_template('single.php') ) {
// A regular expression of what to look for.
$pattern = '/(<img([^>]*)>)/i';
// What to replace it with. $1 refers to the content in the first 'capture group', in parentheses above
$replacement = '<div class="myphoto">$1</div>';
// run preg_replace() on the $content
$content = preg_replace( $pattern, $replacement, $content );
// return the processed content
return $content;
}
else {
return $content;
}
}
add_filter( 'the_content', 'breezer_addDivToImage' );