Extracted from old code, not necessarily recommended

html_to_pdf.pl

sub _html_to_pdf {                                                                           
  my $cb = ref $_[-1] eq 'CODE' ? pop : undef;                                               
  my ($c, $html, $opts) = @_;                                                                
  $opts||={};                                                                                
  require PDF::WebKit;                                                                       
  PDF::WebKit->configure(sub {                                                               
    # default `which wkhtmltopdf`                                                            
    my $exe= $c->executable( 'wkhtmltopdf' );                                                
    $_->wkhtmltopdf($exe);                                                                   
  });                                                                                        
                                                                                             
  my $enc = Mojo::Util::encode 'UTF-8', $html;                                               
  my $kit = PDF::WebKit->new(                                                                
    \$enc,                                                                                   
    'page-size' => 'Letter',                                                                 
    'print-media-type' => 'yes',                                                             
    %{$opts},                                                                                
  );                                                                                         
  return $kit->to_pdf unless $cb; #blocking                                                  
                                                                                             
  require Mojo::IOLoop;                                                                      
  require Mojo::IOLoop::ForkCall;                                                            
  my $fc = Mojo::IOLoop::ForkCall->new;                                                      
  Mojo::IOLoop->delay(                                                                       
    sub { $fc->run(sub{ $kit->to_pdf }, shift->begin) },                                     
    sub {                                                                                    
      my ($delay, $err, $pdf) = @_;                                                          
      die $err if $err;                                                                      
      $c->$cb(undef, $pdf);                                                                  
    },                                                                                       
  )->catch(sub{ $c->$cb($_[1], undef) })->wait;                                              
}