Bug 341842 - Next Page does not work correctly when the view mode is "Facing Pages"
Summary: Next Page does not work correctly when the view mode is "Facing Pages"
Status: RESOLVED NOT A BUG
Alias: None
Product: okular
Classification: Applications
Component: PDF backend (show other bugs)
Version: 0.19.3
Platform: Ubuntu Linux
: NOR wishlist
Target Milestone: ---
Assignee: Okular developers
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2014-12-13 13:21 UTC by Ruy Exel
Modified: 2014-12-14 14:47 UTC (History)
2 users (show)

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Description Ruy Exel 2014-12-13 13:21:03 UTC
When the view mode is "Facing Pages" (Menu: View/View Mode/Pacing Pages) , and "Continuous" (Menu: View/Continuous) is selected, and the user presses <Ctrl-PgDown> (Next Page), then the two pages shown are each scrolled by one half.   

If, instead, "Continuous" is not selected, then it takes two presses of <Ctrl-PgDown> (Next Page) to go to the next pair of pages.

Even though two pages are simultaneosly shown in "Facing Pages" mode,  one should think of them as a single page for the purpose of moving from one page to the next.  That is, a single press of  <Ctrl-PgDown> (Next Page) should fully move to the next pair of pages.  

This is specially important if one is looking for a specific page number in a large PDF file, in which case one would like to stare at the screen where the page number is shown, and by means of several presses of <Ctrl-PgDown>, one would like to see the page numbers changing as if flipping throgh the pages of a real book.

Incidentally Evince (or Document Viewer in Ubuntu) handles "Next Page" i the correct way.

Reproducible: Always

Steps to Reproduce:
1. Open a PDF file with lots of pages
2. Select Menu: View/View Mode/Pacing Pages
3. Select Menu: View/Continuous
4. Press <Ctrl-PgDown> (Next Page) once 
5. Press <Ctrl-PgDown> (Next Page) again 

Actual Results:  
After step 4, nothing happens.
After step 5,  the following pair of pages is shown

Expected Results:  
A single press of <Ctrl-PgDown> (Next Page) should suffice to scroll to the next pair of pages

Okular is great!  Thanks for writing this fantastic program!
Comment 1 Illya Kovalevskyy 2014-12-13 15:35:27 UTC
For some reason I can't confirm this bug on latest ocular from ubuntu apt. Everything works as smooth as possible.
Comment 2 Albert Astals Cid 2014-12-13 16:58:34 UTC
The page, goes to the next page, there's various use cases for that, if you want to scroll to the next viewport use space or just PageDown (while having zoom to fit height)
Comment 3 Ruy Exel 2014-12-13 17:32:06 UTC
Hi Albert, most of the time I have zoom fit to width, in which case I do not know of any key combination which gets me to the top of the next pair of pages.  Do you?
Comment 4 Albert Astals Cid 2014-12-13 17:44:18 UTC
So you have fit width and facing pages, and you want to go to the next pair of pages? What's the use case? You're missing the last bit of the pages, don't you want to read them? To read them you would need to scroll down, and if you've scrolled down already, why not keep scrolling down? Why you need a key to go to the next pair of pages if they are already there?
Comment 5 Ruy Exel 2014-12-13 20:14:50 UTC
Albert, thanks very much for your patience in dealing with my report.  I am aware that my suggestion might not look too crucial, but when people say they prefer reading a book in paper rather than in a computer, I believe these are the little improvements that might tilt the balance towards PDF viewers.

Answering your questions, what I need is to simulate "flicking through pages" of a book, as defined by MacMillan Dictionary: "to turn the pages of a book, magazine, newspaper etc very quickly looking at some of the pages for a very short time".  This is important when searching a large PDF file for a certain page number or a certain pattern whose relative position in the page is already known.

In Okular, under fit width and facing pages, when you attempt to do that with PgDown, the top of the page keeps moving up and down, so you quickly loose your reference point relative to the page.
Comment 6 Albert Astals Cid 2014-12-13 20:46:16 UTC
You can press the next page shortcut twice then, since that's effectively what you want.
Comment 7 Ruy Exel 2014-12-13 21:46:24 UTC
(In reply to Albert Astals Cid from comment #6)
> You can press the next page shortcut twice then, since that's effectively
> what you want.

This is indeed a workaround, but I was hopping for a more elegant solution.
Comment 8 Albert Astals Cid 2014-12-13 23:15:23 UTC
What is the more elegant solution? Next page has to stay since it has its uses, so what you want is a "Next Next page" action which it's trivial to code, it's not about the code is about how to present it to the user, because well "Next Next Page" is really a bad name :D

So if you have a idea for a more elegant solution, i'm listening :)
Comment 9 Ruy Exel 2014-12-14 12:57:31 UTC
(In reply to Albert Astals Cid from comment #8)
> What is the more elegant solution? Next page has to stay since it has its
> uses, so what you want is a "Next Next page" action which it's trivial to
> code, it's not about the code is about how to present it to the user,
> because well "Next Next Page" is really a bad name :D
> 
> So if you have a idea for a more elegant solution, i'm listening :)

"Next Page" is behaving in an incorrect way.  It should take you to the next page, rather than scrolling down each of the two shown pages by half, which it is currently doing when viewing a PDF file provided:

"Facing Pages" mode is selected (Menu: View/View Mode/Facing Pages)
"Continuous" mode is selected (Menu: View/Continuous)
"Fit Width" is selected (Menu: View/Fit Width)

My guess is that the software computes

  1 (press of "Next Page") = 2 (shown pages) X 1/2 (amount each page is scrolled down)

which is mathematically sound but absolutely not what the user expects.

There is a similar bug when "Continuous" is NOT selected.
Comment 10 Albert Astals Cid 2014-12-14 13:36:53 UTC
(In reply to Ruy Exel from comment #9)
> (In reply to Albert Astals Cid from comment #8)
> > What is the more elegant solution? Next page has to stay since it has its
> > uses, so what you want is a "Next Next page" action which it's trivial to
> > code, it's not about the code is about how to present it to the user,
> > because well "Next Next Page" is really a bad name :D
> > 
> > So if you have a idea for a more elegant solution, i'm listening :)
> 
> "Next Page" is behaving in an incorrect way.  It should take you to the next
> page, rather than scrolling down each of the two shown pages by half, which
> it is currently doing when viewing a PDF file provided:
> 
> "Facing Pages" mode is selected (Menu: View/View Mode/Facing Pages)
> "Continuous" mode is selected (Menu: View/Continuous)
> "Fit Width" is selected (Menu: View/Fit Width)
> 
> My guess is that the software computes
> 
>   1 (press of "Next Page") = 2 (shown pages) X 1/2 (amount each page is
> scrolled down)
> 
> which is mathematically sound but absolutely not what the user expects.
> 
> There is a similar bug when "Continuous" is NOT selected.

Your guess is wrong, and besides next page doesn't do that. Next page just goes to the next page.
Comment 11 Ruy Exel 2014-12-14 14:10:45 UTC
> Your guess is wrong, and besides next page doesn't do that. Next page just
> goes to the next page.

it is impossible to carry out a sensible discussion in these terms.  But thanks for your time anyways.
Comment 12 Albert Astals Cid 2014-12-14 14:47:11 UTC
This is not a discussion, this is a bug report, if you're going to guess at how the code does, don't, just show me the code.

If you're going to tell me something like "next page" doesn't go to next page, but the middle of the next page, record a video and show it to me.