[Feature]: "Page Scrolling" mode needs touch control for tablet use

Is the feature relevant to the Firefox PDF Viewer?

Yes

Feature description

I'm using Firefox on a linux tablet. I like flipping trough PDFs in "Page Scrolling" mode (with zoom level set to "Page Fit"). On a device with a keyboard, I can use the arrow right and arrow left keys to navigate. But on a tablet, I have to bring up the on-screen keyboard, which is cumbersome. It would be great if pdf.js could implement gestures for moving to the next or previous page. I would like to stress that I find tapping much more efficient than swiping, so having two tapping zones at the edges left and right would be ideal for me.

Other PDF viewers

KOReader is two my knowledge still the only document reader that is properly optimized for touch control (including for reading PDFs). It supports swiping and tapping the edges.

The rudimentary mobile version of Okular (kirigami-based) allows swiping, but no tapping.

Evince allows swiping, but no tapping. (But the swipe needs to be quite long to be recognized).

I have noticed that pdf.js is being employed in the very promising Thorium ebook reader (which otherwise focuses on EPUBs). In the same way as I have described above for Firefox, it would benefit greatly from gesture control in single page mode.

The issue does not name files or tests. Start by locating the PDF viewer's Page Scrolling mode, existing arrow-key page navigation, and touch input handling; done means tablet users can tap left and right edge zones to move to the previous or next page in single-page mode.