Incorporating a link to a sprintf image - php

Question

I am using the following code to output an image tied to a Wordpress post:
if ( $cover ) :
return sprintf(
'<img src="%1$s">',
$cover
);
endif;
This does output the required image but I need it to be clickable to display the image in full using:
<a href="<?php echo esc_url( $cover( 'medium_large' ) ) ?>">
Please can somebody advise how I can bring the two together?
Thanks.

Answer 1

So, I don't know what your code does, or how are the variables defined, but this will generate the output you want:
function cover($cover = '') {
if ( '' !== $cover ) :
return sprintf(
'<img src="%1$s">',
$cover
);
endif;
}
echo cover('/path/to/my/image.png');
The above will output the following code:
<a href="/path/to/my/image.png">
<img src="/path/to/my/image.png">
</a>
Keep in mind, that I do suppose you already know how to get the post cover image URL, and that's why I have make the function to accept the cover image URL only.
Update #1
If you want to display different sizes images when you click the link you could do the following:
function cover($cover_link = '', $cover_img = '') {
if ( '' !== $cover ) :
return sprintf(
'<img src="%2$s">',
$cover_link,
$cover_img
);
endif;
}
And then use the function cover inside the WordPress loop as following:
if ( have_posts() ) {
while( have_posts() ) {
the_post();
// ... HTML or PHP Code you need for your loop
$cover_link = get_the_post_thumbnail_url(get_the_ID(), 'full');
$cover_img = get_the_post_thumbnail_url(get_the_ID(), 'post-thumbnail');
if ( $cover_link && $cover_img ) {
echo cover($cover_link, $cover_img);
}
// ... HTML or PHP Code you need for your loop
}
}
Update #2
In the above example, I've used the image sizes full and post-thumbnail. In case you need to have custom sizes for your uploaded images you could use in the functions.php code like the following:
add_image_size( 'my_big_image_size', 1000, 1000, true);
add_image_size( 'my_small_image_size', 500, 500, true);
And then, inside the loop, you could change the following code:
$cover_link = get_the_post_thumbnail_url(get_the_ID(), 'full');
$cover_img = get_the_post_thumbnail_url(get_the_ID(), 'post-thumbnail');
To this:
$cover_link = get_the_post_thumbnail_url(get_the_ID(), 'my_big_image_size');
$cover_img = get_the_post_thumbnail_url(get_the_ID(), 'my_small_image_size');