Swiping + panning = usability problem
We know from experience that even on a UI that only has vertical scrolling combined with workspaces UI pattern the users often endup scrolling when trying to swipe between different content. Now, if we add more gestures in the mix it becomes increasingly difficult to perform the swipe gesture when user wants and only when they want.
There are two apps I use almost daily that both have problems with the swipe gestures.
Read It Later
Read It Later stores web content in offline readable form. Often the content fits perfectly to the screen size but sometime, especially when the article contains code examples, user needs to scroll the content horizontally.
User can also navigate between articles by using the horizontal swipe gesture. The UI lacks visual indication that more articles are available but much bigger problem is created by combining the two gestures, swipe and horizontal scrolling.
It is very difficult to scroll to see full article without accidentally performing swipe and jumping into another article. Over time this becomes very annoying. I've learned to scroll articles very, very slowly to prevent this happening. That's not very good user experience.
Aldiko Book Reader
Aldiko book reader is an excellent ebook reader app but it too suffers from a problem with swiping.
Users have three ways for turning pages: tapping either right or left edge of the screen, page changer component that is exposed when tapped in the middle of the screen and swiping.
By default a page of a book is displayed fully. While this is often good way to show pages on tablets or when the file format is EPUB but when reading a PDF book on smartphone screen the text is too small. Users can zoom the page by using two finger scaling gesture. When zoomed in the whole page, naturally, doesn't fit into the screen and user can pan the view by the normal dragging gestures.
Folks at Aldiko have prevented the problem RIL app has by disabling swiping when zoomed in. This solution, while not perfect, is a good one. It weakens the app consistency but on the other hand it prevents annoying accidental actions. The app still has two more ways for users to change pages.
Unfortunately, there are no easy answers to this problem. It is something that should be kept in mind whenever combining panning and swiping gestures.
Nielsen and Norman also talk about difficulties in gestural interfaces. Worth reading: [Gestural Interfaces: A Step Backwards In Usability].
I'd be very happy to hear your experiences and examples of very good implementations. Please leave comment and links to apps that do it right.
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