$this->output

hi all

I did this function to prevent direct linking to images on my site.
if user links https://mydomain/avatar/36/WU8VgWCXx4 and isnt logged in he is taken to the login page.

the MYcontroller handles the logged in user part.

my question doing this the image will always be downloaded nothing in the cache as when I link normally https://mydomain/images/avatar-36-WU8VgWCXx4.jpg

is there a way to achieve this ?

Code:

function app_avatar( $imgsize,$imguserid )
   {
       $filename = '../members/avatars/avatar-x'.$imgsize.'-'.$imguserid.'.jpg';
       if ( file_exists( $filename ) ) {
           header( 'Content-Length: ' . filesize( $filename ) );
           $finfo = finfo_open( FILEINFO_MIME_TYPE );
           header( 'Content-Type: ' . $finfo );
           header( 'Content-Disposition: inline; filename="' . $filename . '";' );
           $jpg = file_get_contents( $filename );
           $this->output->set_output( $jpg );
       } else {
           $filename = "assets/img/no-avatar.jpg";
           header( 'Content-Length: ' . filesize( $filename ) );
           $finfo = finfo_open( FILEINFO_MIME_TYPE );
           header( 'Content-Type: ' . $finfo );
           header( 'Content-Disposition: inline; filename="' . $filename . '";' );
           $jpg = file_get_contents( $filename );
           $this->output->set_output( $jpg );
       }
   }

 Thanks