Touchscreen/keyboardless navigation support

I just discovered qView and I love its minimalism and speed! However, I sometimes use a tablet PC, and the only way to change images without a keyboard is by long-pressing to open the context menu, which is a bit cumbersome. Instead I'd like to suggest the following:

Invisible previous/next buttons

Implement invisible buttons along the left and right edges of the window for previous and next image, respectively. These would have the added benefit of being pressable by the mouse as well. They should stretch from top to bottom of the window. (The question is how wide they should be.)

Thoughts:

Maybe make the width user-configurable for different screen sizes and DPI scaling?
What to do when the window is too narrow? (My suggestion is "nothing" - the user can resize :) )
Windows' default photo viewer shows little arrow icons when you mouse-hover over these regions. Useful for discoverability, but not required.

Nice to have (1): Swipe navigation

Implement next and previous navigation for a single-finger swipe to the left or right.

Thoughts:

Need to distinguish between touch and mouse input? (Or maybe allow mouse-swiping?)
Need to distinguish between a quick swipe and a longer drag to pan the image. (Tolerances for drag distance, length of time?)
Optional: Support swiping with a stylus?

Nice to have (2): Pinch zoom

Implement two-finger pinch zoom.

Thoughts:

Finicky to implement? (Getting it to "feel" just right, etc.)
Optional: Support trackpad as well as touchscreen?

Obviously, the biggest hurdle with testing touch input is that you need an actual touchscreen. I understand if that's an issue.

jurplel / qView