Touch gesture in iFrame component - how?


I have a next problem. In my application, I have an iFrame for output pdf-document in it. I want use classic two-finger gesture for zoom in and out content in iFrame, but it’s not work. It is possible somehow?

Thank you!

If you are loading something like PDF in iframe - the lib can’t affect its rendering behavior.
Does the same gestures work for iframes which created with pure html ( without dhtmlx touch ) ?