Bug 432007 - Okular: No scrolling with non-continuous view
Summary: Okular: No scrolling with non-continuous view
Status: RESOLVED INTENTIONAL
Alias: None
Product: okular
Classification: Applications
Component: general (show other bugs)
Version: 20.12.1
Platform: Debian testing Linux
: NOR normal
Target Milestone: ---
Assignee: Okular developers
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2021-01-23 19:24 UTC by David
Modified: 2022-08-10 18:43 UTC (History)
1 user (show)

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Description David 2021-01-23 19:24:44 UTC
SUMMARY
When browsing a multi-page PDF with fit-to-page zoom and non-continuous view (only one page displayed at a time), okular will not show a scroll/browsing bar, which makes it hard to switch between pages as the only way is by mouse scrolls or by inputing page numbers. I get this might be a by-product of having the scrollbar reflect page-level scrolling when viewing in con-continuous mode, but this is a very common use-case and this issue makes it very annoying.

STEPS TO REPRODUCE
1. Open some multi-page PDF document.
2. Set the zoom through the fit-to-page option.
3. Set the view mode as non-continuous (one page displayed at a time).

OBSERVED RESULT
No scrollbar to select the position within the document.

EXPECTED RESULT
Should have a scrollbar which would allow moving between pages.

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: 
(available in About System)
KDE Plasma Version: 5.20.5
KDE Frameworks Version: 5.77.0
Qt Version: 5.15.2

ADDITIONAL INFORMATION
Comment 1 Laura David Hurka 2021-01-24 13:21:56 UTC
I think it should be this way. The scrollbar is part of the QAbstractScrollArea, and Okular just places pages in the viewport of QAbstractScrollArea. In non-continuous mode, the viewport contains only one page. If that page fits on the screen, the scrollbar can not scroll anything, so Qt hides it.

If Okular shows another scrollbar in that case, that would visually imply the viewport is scrollable, which is not the case. That would be a weird user interface.

I don’t think we need another way to show the current position in the current document. We already have the page par/widget, and the thumbnails bar. The page widget is scrollable with the mouse wheel.
Comment 2 David 2021-01-24 13:24:23 UTC
(In reply to David Hurka from comment #1)
> I think it should be this way. The scrollbar is part of the
> QAbstractScrollArea, and Okular just places pages in the viewport of
> QAbstractScrollArea. In non-continuous mode, the viewport contains only one
> page. If that page fits on the screen, the scrollbar can not scroll
> anything, so Qt hides it.
> 
> If Okular shows another scrollbar in that case, that would visually imply
> the viewport is scrollable, which is not the case. That would be a weird
> user interface.
> 
> I don’t think we need another way to show the current position in the
> current document. We already have the page par/widget, and the thumbnails
> bar. The page widget is scrollable with the mouse wheel.

But you know, every other non-QT PDF viewer shows a document-level scroller when browsing page-by-page with no zoom.
Comment 3 Laura David Hurka 2021-01-25 15:37:21 UTC
There is a document-level scrollbar in the thumbnails view. Why do we need a second one?

If there was a second one, how could I hide it if I don’t need it?

I think there is not enough gain for the programming cost.

Besides, Atril does not have such a second scrollbar.
Comment 4 David 2021-01-25 15:55:10 UTC
(In reply to David Hurka from comment #3)
> There is a document-level scrollbar in the thumbnails view. Why do we need a
> second one?
> 
> If there was a second one, how could I hide it if I don’t need it?
> 
> I think there is not enough gain for the programming cost.
> 
> Besides, Atril does not have such a second scrollbar.

That’s a good point and hadn’t noticed it. Nevertheless, I’d also like to point out that if you do resort to scrolling with the left pane thumbnails then you lose the ability to quickly gasp the content table (which is what shows in that pane by default) and the section you’re currently browsing.

BTW adobe’s PDF reader and foxit, last time I checked both of them, were displaying a scrollbar when browsing like this.
Comment 5 Laura David Hurka 2021-01-26 13:04:22 UTC
The presentation view has this circular page number display. AFAIK that one should be easy to add to PageView in non-continuous view, because it is just another DocumentObserver. It wouldn’t visually contradict a scrollbar.
Comment 6 Wolfgang Scherer 2022-08-10 18:43:47 UTC
I agree with David Hurks, taht the circular progress indicator from presentation view would be a real enhancement to non-continous page view.