User controlled zoom

Currently using Cap 9.

Is there a way to create a user controlled zoom feature?  Example, if the user is looking at a screen shot on a PC based eLearning, is there a way for them to zoom in on the content (other than Ctrl +)?  Or if the user is viewing a lesson on a mobile phone, can they zoom in and out?  Other than a Roll Over. 

Ideally, for PC based lessons, I'd like something simple like a zoom bar (similar to the ones found in MS Word or Excel).  Also, I want them to be able to zoom on the content and not lose sight of the skin and nav buttons.