HTC One M9+ Supreme Camera Edition User Manual page 41

41 Your first week with your new phone
Slide with two fingers
Two-finger swipe
Swipe down from the status bar using two fingers to access Quick Settings.
In some apps, like Gallery, Messages, Mail, or
the web browser, slide two fingers apart to zoom
in when viewing a picture or text.
Slide two fingers together to zoom out of the picture or text.