Get the size (size in Kb or MB) of an featured image?

Question

I need to display some featured image info on post page. Among other info I need to display file size of image (featured image of post).

I tried this function inside single.php.

<?php
function getSize($file){
   $bytes = filesize($file);
   $s = array('b', 'Kb', 'Mb', 'Gb');
   $e = floor(log($bytes)/log(1024));

  return sprintf('%.2f '.$s[$e], ($bytes/pow(1024, floor($e))));
}
?>

and to echo that:

<?php echo getSize('/wp-content/uploads/2014/06/some-file-name.jpg'); ?>

It works, but I need help to make ti automatically grab featured image url, not to manually enter it in code?

For example I use this to echo featured image ("full") url:

 <?php
 if ( has_post_thumbnail()) {
   $full_image_url = wp_get_attachment_image_src( get_post_thumbnail_id($post->ID), 'full');
echo $thumb_image_url[0];
 }
?> 

Could you please help to combine it, or to provide me with another solution?

Answer 1

You can use get_attached_file() to:

Retrieve attached file path based on attachment ID.

And get_post_thumbnail_id() to determine the post thumbnail of the current post, or any post if you set the $post_id parameter. Exemplary usage:

$bytes = filesize(
    get_attached_file(
        get_post_thumbnail_id()
    )
);

Use size_format() to

Convert a given number of bytes into a human readable format

$hr_size = size_format( $bytes );

If you are actually want to get the size of one of the intermediate sizes, the above shows the file size of the full image, make use of image_get_intermediate_size(), where:

The metadata 'sizes' is used for compatible sizes that can be used for the parameter $size value.

Which means it uses wp_get_attachment_metadata() to get the data. In addition you need wp_upload_dir() to construct the path. Exemplary usage:

$upload_dir = wp_upload_dir();
$metadata_size = image_get_intermediate_size( 
    get_post_thumbnail_id(),
    'thumbnail'
);
$path_inter = $upload_dir[ 'basedir' ] . '/' . $metadata_size[ 'path' ];
$bytes = filesize(
    $path_inter
);
$hr_size = size_format( $bytes );