It depends on what kind of scrolling you expect.
With the Scrollview views you have no control on the scrolling process, you don't control when it stops.
For your example of a full screen image veiwer i'm not convinced that the ScrollView is the best solution for the reason above.
For a full screen image viewer I think that sliding panels would be better because after having initiated the scrolling, the panel scrolls to the next known position, the next image, and would not stop anywhere in between as with the ScrollViews.
Have a look at the two examples below with a vertical ScrollView, the same can be done with a HorizontalScrollView. In these examples the images are ImageViews in a single Panel, the internal ScrillView.Panel.
http://www.b4x.com/forum/basic4andr...ials/6612-scrollview-example-2.html#post38619
http://www.b4x.com/forum/basic4andr...85-add-imageview-half-manually.html#post43655
The number of images you could scroll is the memory limt, and with big images this will become a problem.
With sliding panels you could do it with just two or three panels and
loading the images only when needed.
Did you have a look at
BetterSlidingPanels ? You could do something similar with the Touch event instead of Buttons.
Best regards.