How to change url expression for 'Print this' document_action in Plone to be used with for collective.documentviewer?

How to change url expression for 'Print this' document_action in Plone to
be used with for collective.documentviewer?

I am using Plone unified installer 4.1.4 and wish to change the URL
Expression for the portal_actions, document_actions for 'Print this'. so
that the same can be enabled for collective.documentviewer. I got this
reference from [enter link description here][1]Print / Fullscreen / Email
icons
Using this however only the contents of the current window are printed and
not the contents of the file being displayed in the viewer. I am not good
at javascript. If anyone could please revert with the javascipt
expression, I will be grateful.
Note: I do not wish to download the file from document viewer by clicking
the 'Original Document' as is the default behaviour of the viewer, but
wish to print the contents of the file from the viewer directly.