Bug 140577 - Writer in "Web" view mode becomes unresponsive and flickers when the window is resized or zoom is adjusted when a long document is displayed
Summary: Writer in "Web" view mode becomes unresponsive and flickers when the window i...
Status: RESOLVED INSUFFICIENTDATA
Alias: None
Product: LibreOffice
Classification: Unclassified
Component: Writer (show other bugs)
Version:
(earliest affected)
7.0.4.2 release
Hardware: All All
: medium normal
Assignee: Not Assigned
URL:
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Keywords:
Depends on:
Blocks:
 
Reported: 2021-02-21 05:22 UTC by ckoresko
Modified: 2023-03-31 03:29 UTC (History)
1 user (show)

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Description ckoresko 2021-02-21 05:22:27 UTC
Description:
When working with a long (>50000 words, say) document using Writer in Web view mode, changing the zoom setting or resizing the window appears to trigger a reflow operation of the whole document, which can render Writer unusable for 10s of seconds before the display stabilizes.  During this time it uses a full CPU core.

Steps to Reproduce:
1. Load a long document into Writer.  The document should not have hard line breaks.
2. Scroll to the end of the document.
3. Using the mouse, expand or shrink the width of the Writer window, or change the Zoom setting.

Actual Results:
Document display flickers and CPU usage is high while Writer reflows the document.    Eventually the display becomes stable and Writer can be used normally until another change to the zoom setting or window geometry occurs.

Expected Results:
The display does not flicker.  Writer remains responsive.


Reproducible: Always


User Profile Reset: No


OpenGL enabled: Yes

Additional Info:
I suspect that this happens because the document is being redisplayed during the calculated reflow operation.  I don't know the inner workings of Writer, but perhaps it would be possible to first calculate the new locations of the line-wraps in a background thread while the display continues to reflect their positions with the previous zoom and window geometry.  I think the horizontal scrollbar would have to be displayed if the window width is reduced or the zoom is increased.  Then the display could be updated in one fast operation when the reflow calculation thread exits.

Version: 7.0.4.2
Build ID: 00(Build:2)
CPU threads: 2; OS: Linux 5.10; UI render: default; VCL: gtk3
Locale: en-US (en_US.UTF-8); UI: en-US
Calc: threaded
Comment 1 Dieter 2021-09-08 04:37:44 UTC
Ckoresko, unfortunately nobody could confirm this bug report during the last months. So I'd like to ask, if it is still valid. Could you please try to reproduce it with the latest version of LibreOffice from https://www.libreoffice.org/download/libreoffice-fresh/ ? I have set the bug's status to 'NEEDINFO'. Please change it back to 'UNCONFIRMED' if the bug is still present in the latest version.
Comment 2 ckoresko 2021-09-21 15:24:45 UTC
Dieter,

Thanks for looking into this.  I did a quick test with document containing about 100000 words and a bunch of figure and tables.  I loaded it into Writer 7.1.6.2.0+, which I think is the current Still version, on Fedora 34 amd64 in a VirtualBox VM on an Windows host.  I also exported it to a docx file and loaded it into Word 2013 running on the same host.  So the hardware was the same for both programs, though the VM probably slowed Writer down a little.  

I set both Writer and Word to display in "Web" mode, scrolled to the bottom of the document, and clicked the "+" zoom button.  Writer finished the task in 48 seconds and Word did it in about 3 seconds.  I believe Writer's poor performance doing this type of reflow is the basic issue.

I realize that the above test still leaves some uncertainties.  I'll try to put together a more apples-to-apples test (same OS and hardware).  But I don't think it'll change the results enough to account for the >10x difference in speed.
Comment 3 QA Administrators 2021-09-24 04:07:40 UTC Comment hidden (obsolete)
Comment 4 ckoresko 2021-09-25 01:07:13 UTC
Downloaded "fresh" 7.2.1.2 and tested it on the same platform.  The time to reflow the document after a zoom setting change has approximately doubled compared to the 7.1.6.2.0+ version.
Comment 5 Dieter 2021-09-25 10:37:38 UTC
(In reply to ckoresko from comment #4)
> Downloaded "fresh" 7.2.1.2 and tested it on the same platform.  The time to
> reflow the document after a zoom setting change has approximately doubled
> compared to the 7.1.6.2.0+ version.

Is it possible for you to provide a sample document?
Comment 6 Dieter 2022-08-31 06:09:46 UTC
(In reply to Dieter from comment #5)
> Is it possible for you to provide a sample document?
Please add such a document

Also a new major release of LibreOffice is available since this bug was reported. Could you please try to reproduce it with the latest version of LibreOffice from https://www.libreoffice.org/download/libreoffice-fresh/ ?

I have set the bug's status to 'NEEDINFO'. Please change it back to 'UNCONFIRMED' if the bug is still present in the latest version and you can provide a test file.
Comment 7 QA Administrators 2023-02-28 03:19:56 UTC Comment hidden (obsolete)
Comment 8 QA Administrators 2023-03-31 03:29:39 UTC
Dear ckoresko,

Please read this message in its entirety before proceeding.

Your bug report is being closed as INSUFFICIENTDATA due to inactivity and
a lack of information which is needed in order to accurately
reproduce and confirm the problem. We encourage you to retest
your bug against the latest release. If the issue is still
present in the latest stable release, we need the following
information (please ignore any that you've already provided):

a) Provide details of your system including your operating
   system and the latest version of LibreOffice that you have
   confirmed the bug to be present

b) Provide easy to reproduce steps – the simpler the better

c) Provide any test case(s) which will help us confirm the problem

d) Provide screenshots of the problem if you think it might help

e) Read all comments and provide any requested information

Once all of this is done, please set the bug back to UNCONFIRMED
and we will attempt to reproduce the issue. Please do not:

a) respond via email 

b) update the version field in the bug or any of the other details
   on the top section of our bug tracker

Warm Regards,
QA Team

MassPing-NeedInfo-FollowUp