nothing much to see here... just like the title says.
The path for the image can be anything. The only reason I did it outside of WP is to keep the images away from the uploader so the client & employees would have a harder time deleting it.
/**
* Add data attributes to the custom logo.
*/
add_filter( 'wp_get_attachment_image_attributes', function ( $attr ) {
if ( isset( $attr['class'] ) && 'custom-logo' === $attr['class'] ) {
$attr['data-small-logo'] = '/path/to/small/image.jpg';
// or this way
// $attr['data-small-logo'] = get_template_directory_uri() . '/path/to/small/image.jpg';
$attr['data-medium-logo'] = '/path/to/medium/image.jpg';
// or this way
// $attr['data-medium-logo'] = get_template_directory_uri() . '/path/to/medium/image.jpg';
}
return $attr;
} );