Bug 128908 - Impress font rendering problem in presentation mode still not solved
Summary: Impress font rendering problem in presentation mode still not solved
Status: RESOLVED INSUFFICIENTDATA
Alias: None
Product: LibreOffice
Classification: Unclassified
Component: Impress (show other bugs)
Version:
(earliest affected)
6.0.7.3 release
Hardware: x86-64 (AMD64) Linux (All)
: medium normal
Assignee: Not Assigned
URL:
Whiteboard:
Keywords:
Depends on:
Blocks:
 
Reported: 2019-11-20 07:54 UTC by Michael
Modified: 2021-07-30 09:05 UTC (History)
1 user (show)

See Also:
Crash report or crash signature:


Attachments
example page causing the font rendering issue (32.33 KB, application/vnd.oasis.opendocument.presentation)
2019-11-20 10:11 UTC, Michael
Details

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Description Michael 2019-11-20 07:54:33 UTC
The problem
https://ask.libreoffice.org/en/question/98075/impress-incorrect-font-rendering-in-presentation-mode/
still exists in version 6.0.7.3 which comes along with Ubuntu 18.04.

OpenCL is on. If I turn of hardware acceleration, fonts are fine, but graphics are unacceptable quality.

If I turn on HW-acceleration, fonts are rendered in half-size at random places, sometimes single letters. Difficult to enforce, sometimes this vanishes when changing font.

This is critical, because without proper rendering, a presentation tool is useless.
Comment 1 Michael 2019-11-20 08:32:03 UTC
The problem still exists in version 6.3.3.2.

When I change the magnification (under display preferences) to 100%, the problem vanishes.

Apparently the problem is caused by some internal confusion in the rendering whether the content should be rendered at full size or 50% size - and this factor varies inside the textbox.

Setting magnification to 100% is not a good idea if the internal display is 4k, but it is a workaround until the issue is solved.

As a side remark: the projector was 1920x1200 whereas the internal screen is 4k. If the laptop is connected to an external 4k screen, no issue with the scaling exists.
Comment 2 Mike Kaganski 2019-11-20 08:44:04 UTC
1. The problem you mention is reported for Windows; it was specifically mentioned by its poster:

> Actually my issue ... was only present in the Windows version; running Linux
> was fine but required the hardware acceleration to be enabled

So your case is obviously different (Linux, and HW acceleration *breaks* things). It doesn't help to pick a random report in a random place and cite it as confirming/explaining something.

2. Your description lacks any sign of reproduction steps. It doesn't allow one to test *something* (e.g., a test document) in a test environment (e.g., with specific GPU+drivers that you also don't mention), and see the problem. Please provide that information.

Also note, that the "Version" field has that "earliest affected" description, just to let you know that you should *not* change it to a later version when you discover it's still there in a later release.

Thanks!
Comment 3 Michael 2019-11-20 10:11:25 UTC
Created attachment 155968 [details]
example page causing the font rendering issue
Comment 4 Michael 2019-11-20 10:17:04 UTC
Regarding 1. I picked the wrong URL from the paste buffer. I am a bit under stress since I need to get my lecture working by tomorrow, sorry for the confusion.

Regarding 2. I now added a file with the page that renders wrongly if HW-acceleration is on in my system (Nvidia GeForce GTX 1050 with Ubuntu 18.04 and nvidia-driver-435).
Comment 5 QA Administrators 2019-11-21 03:33:32 UTC Comment hidden (obsolete)
Comment 6 Kai 2020-01-31 03:24:07 UTC
Can confirm this on Linux (Ubuntu 19.10) with 6.4 and 6.5. Text looks okay when hardware acceleration is disabled. 

This is basically why I have not been using LO for the last few years...
Comment 7 Kai 2020-02-09 04:48:24 UTC
Here's the best way to work around this issue, imho.

If you are running under Wayland, start libreoffice as a X11 client like so: env GDK_BACKEND=x11 libreoffice6.4

XWayland renders to smaller buffer and automatically upscales everything to whatever your HighDPI settings are.
You lose some image quality but it's still better than having a tiny UI or not being able to use animations altogether.
Comment 8 Michael 2020-02-19 09:40:48 UTC
I tried this workaround and I think the font sizes are consistent now.

However, everything is re-scaled so all slides need to be manually re-arranged.

Thus, this is no real option.

If you do not want to compromise quality or re-do all slides, the IMHO only workaround is to enforce 100% display size (display settings dialogue) before pressing F5 (playing the presentation).
Comment 9 Oliver Grimm 2020-03-06 21:49:44 UTC
setting to NEW, since Kai confirmed it :-)
Comment 10 Kai 2020-06-16 22:35:13 UTC
This seems to be fixed in 7.0.

Also, I think #130481 is duplicate.
Comment 11 Timur 2020-06-17 20:15:45 UTC
Kai, thanks for testing. Since it's only Michael now who confirmed, I set Needinfo for him to test. Please do with https://dev-builds.libreoffice.org/daily/master/current.html
Comment 12 Michael 2020-06-23 14:47:55 UTC
If I see this correctly, 7.0 is still beta. On my work machine I can test as soon as it is release.
Comment 13 Timur 2020-06-23 14:57:47 UTC
OK, you may wait and use 7.0 release.
But for bugs, best is to test with current master, which is now 7.1+.
It installs separately to working LO and doesn't take extensions. 
Link is https://dev-builds.libreoffice.org/daily/master/current.html
Comment 14 QA Administrators 2020-12-21 03:44:08 UTC Comment hidden (obsolete)
Comment 15 Michael 2020-12-21 08:51:23 UTC
Wanted to test on 7.0.4.2 (7.1 is still beta which I may not run on my machine).

However, Ubuntu 20.04 does no longer allow to have different scales on my two displays. Thus both are always on the same resolution (either 100% or 200%) and I cannot test whether the bug is still present.
Comment 16 QA Administrators 2020-12-22 03:43:48 UTC Comment hidden (obsolete)
Comment 17 Dmitriy Siushkin 2021-07-30 07:25:32 UTC
no repro in 

Version: 7.3.0.0.alpha0+ (x64) / LibreOffice Community
Build ID: c5ca46e75e28ba4245d8544ca53c71fea87d1bbd
CPU threads: 4; OS: Windows 10.0 Build 19043; UI render: Skia/Raster; VCL: win
Locale: en-US (ru_RU); UI: en-US
Calc: CL
Comment 18 Timur 2021-07-30 09:05:12 UTC
I guess we can only close this one, because we have no confirmation now.