Zoom not working in book mode

[silviolosi]

When using the library in book mode, I zoom into the PDF (for example using the trackpad gesture).

After zooming in, I expect to be able to drag the document to move around the zoomed area (pan behavior).

However, when I try to drag with the mouse (click and hold), instead of moving the zoomed content, the viewer switches pages as if I were flipping through the book.

So the drag gesture is interpreted as a page turn instead of a pan action on the zoomed document.

Expected behavior:
When the PDF is zoomed in, dragging should move (pan) the zoomed content.

Actual behavior:
Dragging triggers page navigation (book page flipping) instead of moving the zoomed area.

I'm using version 25.6.0-rc.3

[stephanrauh]

Off topic: I suggest updating to version 25.6.0 (the final version) or 26.0.0-rc.1.

As for your issue: well, it's still book mode. How to distinguish a drag gesture from a page-turn gesture?

We could do something else. Currently we have the "hand mode" (which drags / scrolls the PDF) and "selection mode":

We could implement something similar in book mode. Let me ponder about it. It's not trivial to implement the "book hand mode". Book mode is always capricious, and that'd require me to implement a new feature.

[silviolosi]

It would be possible to expose a configuration option to disable page flipping via drag and keep it only on click. This way, when zooming, the “page flip” effect would no longer be triggered, which in my opinion is actually quite inconvenient.

On desktop, the flip is triggered with the mouse and it’s not very user-friendly. On mobile devices, book mode makes PDFs appear very small, so zooming would be much more useful than page flipping.

There are a couple of libraries that could be used as inspiration, such as js_dearflip or FlippingBook.