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Bug 124505 - Add single slide show across all displays as "All displays" in addition to existing to be renamed to "Span displays"
Summary: Add single slide show across all displays as "All displays" in addition to ex...
Status: NEW
Alias: None
Product: LibreOffice
Classification: Unclassified
Component: Impress (show other bugs)
(earliest affected) release
Hardware: All All
: medium enhancement
Assignee: Not Assigned
Depends on:
Blocks: Slide-Show Presenter-Console
  Show dependency treegraph
Reported: 2019-04-02 16:36 UTC by AtesComp
Modified: 2020-07-30 11:11 UTC (History)
4 users (show)

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Crash report or crash signature:


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Description AtesComp 2019-04-02 16:36:19 UTC
Impress displays a single, large slideshow across multiple displays when using the "Slide Show" ->  "Slide Show Settings" -> "Multiple Displays" -> "Presentation display:" -> "All displays" setting.

This applies to all VCL modes (gtk, gtk3, gen).  The "gen" mode (X11) only uses two (2) displays as a single display.  This may be due to one display being offset from the others.  The "gtk" modes use all (in my case 3) displays (ignoring any offsets).  In every case, the displays are used as one big single display instead of several independent displays with duplicate slide shows.

I expect "kde" modes will do the same, but there is currently another outstanding bug 124484.

1. This may be due to the DE's display control.  The displays are not "unified", so I would expect them to be seen as independent.  Using "unified" should duplicate the screens as expected (untested).

2. This may be due to the graphics driver--in this case, Nvidia.  Nvidia has a "X screen 0" consisting of all the display as well as individual displays within it.  The slide show is probably detecting the "one display to rule them all"(tm).

Steps to Reproduce:
1. Open Impress with any presentation
2. Set "Slide Show" ->  "Slide Show Settings" -> "Multiple Displays" -> "Presentation display:" to "All displays"
3. Start a slide show

Actual Results:
Slide show is shown across all displays as one big show.

Expected Results:
Each display shows a duplicate of the slide show.

Reproducible: Always

User Profile Reset: No

Additional Info:
This may need to be set as an enhancement.

There is a use case for each of the following:

1. "All displays as a single display" -- all displays are interpreted as a single display to present one big slide show.  This is the current functionality (mostly).

2. "All displays as individual displays" -- each display is considered separate to present duplicate slide shows on each monitor.
Comment 1 mattia.b89 2019-09-07 18:20:08 UTC
I confirm the issue

Build ID: 6.3.1-1
CPU threads: 4; OS: Linux 5.2; UI render: default; VCL: gtk3; 
Locale: it-IT (en_GB.UTF-8); UI-Language: en-GB
Calc: threaded
Comment 2 Xisco Faulí 2019-10-16 12:17:04 UTC
Hello AtesComp,
so just to understand this enhancement, if you select All displays and you have 2 displays, one on top of the other, you would like to see half of the presentation on the upper screen and the other half on the lower one ?
Comment 3 AtesComp 2019-10-16 17:03:27 UTC
@xiscofauli: Thanks for looking at this.  Yes and No.

The current documentation of the existing function says it "spans all displays".  Originally, I believe it meant to present the slideshow independently on each display (I could be wrong).  It attempts to span--display a section of the slideshow on each display.  It should do like you are suggesting: honor the actual monitor position.  Maybe it doesn't handle top to bottom so well.  I didn't test that configuration.

However, as an enhancement, maybe two features should be implemented as separate use cases:

1. Display as a single presentation spanning across all displays using the DE's display manager settings to determine the placement of each section.  This would probably be a significant undertaking as it requires finding/calculating the overall virtual screen size, determine each monitor's pixel coverage based on top to bottom and left to right orientation, sectional calculations to determine what portion displays where while dealing with gaps (offsets) between displays, and other issues.  It would be desirable to optionally hold one display as the "presenter's display" (primary display, if there is a primary display? or user selection) similar to the other options (see note below).

2. Display as multiple presentations on each individual display.  This should be relatively simple to implement as it replicates the presentation on each display.  It would also be desirable to optionally hold one display as the "presenter's display".

NOTE: The other options select the displays a bit differently--Impress asks which display is the "presentation display" as opposed to which display is the "presenter's display" with the clock and notes.  Maybe it should ask for both the "presenter's display" and the presentation display as per the above options.

So maybe the UI should have:

Multiple Displays:

[ ] Span presentation across displays

Presenter's Display:  Auto (selecting the main display or first display)
                      Display 1
                      ... (list all other displays)

Presentation Display: All (minus the presenter's display if selected;
                           this might be the only option if Span is on)
                      Auto (selecting the next--or first--display)
                      Display whatever
                      ... (list all other displays)

Of course, if the DE has setup a "unified display" for multiple monitors, then Impress should probably honor the setting as a single display.  This would be like option 2 above (no span) with no "presenter's display".

One of the issues with using the system as currently implemented, is that when you have a row of displays (say 3 or more) and a standard presentation, the presentation is centered and the outer left and right portions are just black, dead space (as it should be).  But, I also lose the presenter's display (I might as well not use the "all" option).  With a rectangular array of monitors and a presenter's display, this option could potentially be awesome.
Comment 4 QA Administrators 2019-10-17 02:38:05 UTC Comment hidden (obsolete)
Comment 5 Timur 2019-11-22 10:48:41 UTC
Help says:
"If the system allows the user to span a window over all available displays, you can also select "All displays". In this case the presentation is spanned over all available displays."

Useful if you have 2 or 3 displays and you wasn't it all and different. 
Normal presentation is shown wrong, half of the slide on each display. 
Please test and attach a doubled (and trippled?) presentation that would work fine. Or that's the bug.
Comment 6 Timur 2019-12-02 13:41:24 UTC
So far, we have that initial expectation "Each display shows a duplicate of the slide show" is NotABug. 
Actual "Slide show is shown across all displays as one big show" is per Help how it should work.
What we don't have confirmed is that one single presentation can be spanned over 2 (or 3) displays. 
I don't know if that can be a normal one (but that's shown wrong for me, half of the slide on each display) or we need a custom one. 
This bug is NeedInfo to answer that and attach such a presentation.
Comment 7 Timur 2019-12-08 10:29:31 UTC
Needinfo gets closed after a while. Here, it's New, there's a bug, only we need to know if it's implementation or documentation.

When I create a slide it's 16:9 with size 28,00 x 15,75 cm.
When I increase width to 56 cm, it works as expected, content divided on two monitors.
So, if there's a bug, that's to add predefined double size for existing 3 screens. It's trivial.

All displays is available from LO 3.3 but wasn't working then and works now.
Comment 8 Heiko Tietze 2020-01-08 11:12:39 UTC
Maybe I don't understand the request with "manual double width". First option is when you select a particular display to show the presentation/slide X

| X  |    |
|    |    |

Option b) is when the slide X should spawn over all displays (meaning X1 is the upper left quarter of slide X)

| X1 | X2 |
| X3 | X4 |

and if "All displays" is checked I expect a duplication.

|  X | X  |
|  X | X  |

To me, all further advanced display configuration is up to the screen management software.
Comment 9 Timur 2020-01-08 13:37:21 UTC
"manually double slide width" is what I explained in Comment 7: change predefined slide size 28,00 x 15,75 cm to a custom width of 56 cm.
Comment 10 Heiko Tietze 2020-01-08 15:08:51 UTC
What's the point of doing this?
Comment 11 Heiko Tietze 2020-07-06 09:48:33 UTC
UX input done in comment 8, removing the keyword now.
Comment 12 AtesComp 2020-07-06 13:47:08 UTC
Don't hijack the bug to fix your limited idea of the issue. Heiko Tietze has it right.  The solution is pointless as it does not address the issue at all.  No one can rely on sizing the presentation to fit any given monitor size...especially when moving the presentation from a desktop to a multi-monitor class or theater display system.  The problem as titled and presented is exactly the issue.

Contrasting comment 6, the presentation should scale the presentation as per Heiko Tietze in comment 8 with possible dead space surrounding if the presentation doesn't fit nicely.  The bug should not be recast as some other issue.
Comment 13 Timur 2020-07-29 17:51:47 UTC
This bug started wrong, requesting a change of existing option, when indeed it needs another option, which is justified. So I change the title.