Bug 343910

Summary:	horizontal continuous scrolling
Product:	[Applications] okular	Reporter:	Ansa <ansa.ansa>
Component:	general	Assignee:	Okular developers <okular-devel>
Status:	REPORTED ---
Severity:	wishlist	CC:	azrdev, gerion.entrup, peter.meilstrup, ryan, stefan.bruens
Priority:	NOR
Version:	0.19.3
Target Milestone:	---
Platform:	Kubuntu
OS:	Linux
See Also:	https://bugs.kde.org/show_bug.cgi?id=371904 https://bugs.kde.org/show_bug.cgi?id=439417
Latest Commit:		Version Fixed In:

Description Ansa 2015-02-07 22:28:01 UTC

This wish has been reported for the kpdf app and has not been granted yet: https://bugs.kde.org/show_bug.cgi?id=140589

This is a wish for "horizontal continuous mode". Every now and then I have a scanned book, which means that the pdf has horizontal pages that contain 2 of the original pages. I would appreciate the "left to right" reading mode, which would make it possible (with the right zoom) to view any two or even three consecutive pages of the original book simultaneously (the one I am reading, the preceding one and the following one), i.e. one and a half page of the pdf file. Currently, I may view this: 1-2 3-4 5-6 In double mode, I may choose from 1-2 3-4 5-6 and 1-2 3-4 5-6 The horizontal continuous mode would give me 1-2 3-4 5-6 (with the possibility to zoom onto "2 3" as well).

A simple solution to this problem would consist of two (hopefully) minor adjustments to Okular:
- extend the "Overview columns" from maximum 8 columns to unlimited number -- setting this to N, where N is the number of pages in the document, and then adjusting the zoom to exactly fit page height (but not to fit page width) exactly provides the "horizontal continuous scroll" that I am wishing for.
+ provide "Zoom: fit height" option (similar to "Zoom: Fit width" and "Zoom: Fit page") both in the Zoom dropdown list and as an icon that can be added to the toolbar

Reproducible: Always

Comment 1 David Hurka 2019-12-04 20:38:27 UTC

*** Bug 414796 has been marked as a duplicate of this bug. ***

Comment 2 David Hurka 2020-06-06 13:25:20 UTC

I don’t think extending the Overview column limit is the right way. What should the limit be? Imagine you read an A4 format flyer with 6 pages, so you are happy to turn on Overview mode and Fit Width. Then you open your favorite instruction set summary, and get one horizontal line of pages, which are 0.05px height each.  This will be invisible, so it looks like Okular is broken. Requesting all 25,000 page pixmaps at once would probably indeed crash Okular.

> + provide "Zoom: fit height" option (similar to "Zoom: Fit width" and "Zoom: Fit page")

Fit Width wouldn’t make sense for horizontal continuous mode (for the explained reason), so Fit Width and Fit Height could be the same option, right? (In the sense of Zoom to Fill)

Comment 3 David Hurka 2020-06-06 13:30:35 UTC

*** Bug 390709 has been marked as a duplicate of this bug. ***

Comment 4 Ryan 2021-11-26 03:58:58 UTC

Continuous horizontal scrolling is an important feature for me. It is available in PDF-XChange, which I pay for and use mainly because of this feature. However, PDF-XChange is a commercial application for Windows only.
My primary use case is reading and adding annotations to scientific journal articles. Typically, these have a two-column layout that makes vertical scrolling awkward. In contrast, continuous horizontal scrolling:
- always places related columns adjacent to each other;
- allows use of the full horizontal space of a wide screen, making it easier, for instance, to view a graph or table on one page while referring to related text on another page; 
- provides the flexibility to view even-odd page-pairs (with the even-numbered page on the left); and
- the reading experience is more natural than vertical scrolling (for material that represents printed media), because left/right scrolling moves in the same direction as a physical page-turn.
In PDF-XChange, rolling the mouse wheel up/down scrolls left/right (or right/left) if the page view is zoomed to page height or less. When the zoom is greater than full page height, the wheel changes to up/down scrolling. Left/right scrolling is still possible with a tilting mouse wheel or using the grabber (pan tool).
Continuous horizontal scrolling is remarkably useful, yet not found in any other PDF application, to my knowledge, other than PDF-XChange. It would be great to see this added to Okular.

Comment 5 Ryan 2021-11-26 04:41:53 UTC

(In reply to Ryan from comment #4)

> Continuous horizontal scrolling is remarkably useful, yet not found in any
> other PDF application, to my knowledge, other than PDF-XChange.

Correction: the PDF viewer in Firefox (94.0.1) includes horizontal scrolling.

Comment 6 Ryan 2021-11-26 05:17:28 UTC

(In reply to David Hurka from comment #2)
> Fit Width wouldn’t make sense for horizontal continuous mode
Fit Width should fit the width of exactly one page -- the current page -- regardless of its orientation, and not the total width of a multi-page document.
> Fit Width and Fit Height could be the same option
This would depend on size and orientation of the monitor and page displayed. With a 16x9 monitor, for example, in landscape orientation, vertical space is usually the constraint (if the page is of A4 or letter size and in portrait orientation), so Fit Page and Fit Height would produce the same result. With the monitor in portrait orientation, horizontal space would become the constraint, meaning that Fit Page and Fit Width would now produce the same result, whereas Fit Height would fill the screen vertically, leaving one or both sides of the page out of view.

Comment 7 Ryan 2022-02-22 22:19:01 UTC

*** Bug 443909 has been marked as a duplicate of this bug. ***