Bug Hunting Session
Bug 119608 - VIEWING: Diacritical marks become visible only after changing view in Writer
Summary: VIEWING: Diacritical marks become visible only after changing view in Writer
Status: NEW
Alias: None
Product: LibreOffice
Classification: Unclassified
Component: Writer (show other bugs)
Version:
(earliest affected)
5.4.6.2 release
Hardware: x86-64 (AMD64) Linux (All)
: medium normal
Assignee: Not Assigned
URL:
Whiteboard:
Keywords:
Depends on:
Blocks: Font-Rendering
  Show dependency treegraph
 
Reported: 2018-08-30 13:54 UTC by vaaydayaasra
Modified: 2019-10-07 15:46 UTC (History)
4 users (show)

See Also:
Crash report or crash signature:


Attachments
Writer view as the user is typing (99.91 KB, image/png)
2018-08-30 13:55 UTC, vaaydayaasra
Details
Writer view after the screen has changed (99.58 KB, image/png)
2018-08-30 13:56 UTC, vaaydayaasra
Details
Writer view after removing the text (92.05 KB, image/png)
2018-08-30 13:56 UTC, vaaydayaasra
Details
Just an example image from master build (4.58 KB, image/png)
2018-10-01 15:12 UTC, Jan-Marek Glogowski
Details
The example document used for the screenshot (8.85 KB, application/vnd.oasis.opendocument.text)
2018-10-01 15:13 UTC, Jan-Marek Glogowski
Details

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Description vaaydayaasra 2018-08-30 13:54:06 UTC
Description:
Arabic is sometimes written with diacritical vowel marks, which are placed either above or below each letter of the word. Many multipurpose fonts, which are not designed specifically for Arabic, place some of these marks in the empty space between lines, outside of the space reserved for line height. Writing Arabic in LibreOffice Writer, these marks don't become visible while typing but only after the page view has changed once.

See the attached series of screenshots, where the first screenshot has been taken while typing. The first letter of the first word (reading from right to left) should have two diacritical marks: ء and a diagonal line above the letter: أَ. Only the lower half of the ء mark is visible and the diagonal line not at all. The second letter of the same word has a circle on top of it but only the lower half of it is visible. Equally so for the third word of the sentence بِبَرْنَامِجِ, where the last letter of the word has a diagonal line below, but it is not visible at all. The second screenshot has been taken after I scrolled the page down by a couple of screens and then scrolled back. Now all the diacritics are shown as they should. In the third screenshot I have deleted all of the text I typed but as you can see, some parts of the diacritics are still visible above the line. If I scroll down and back, they would disappear. If you want to test it yourself, the sentence I wrote reads "أَكْتُبُ هُنَا بِبَرْنَامِجِ لِيبَرْ أُفِيسْ".

This problem is similar to https://bugs.documentfoundation.org/show_bug.cgi?id=85426 but does not involve fixing line spaces. Even the font I'm using is different (DejaVu Sans).

This bug was first reported on Launchpad for LO 5.4.6.2 on Ubuntu 17.10 at: https://bugs.launchpad.net/ubuntu/+source/libreoffice/+bug/1772451 . After my initial report, I have upgraded to LO 6.0.3.2 and can still reproduce the problem. On Launchpad, I was advised to file this report separately from 85426, as I was not sure whether it is exactly the same issue or just related to it.

Steps to Reproduce:
1. Type Arabic text with full vowel marks, including low diacritics under letters extending below the baseline and high diacritics on top of high letters.
2. Remove the text by pressing backspace.

Actual Results:
Many vowel diacritics or parts of them become visible only after the view is changed, and removing a character sometimes leaves the diacritic or part of it visible on the screen, although textually it doesn't exist anymore.

Expected Results:
All diacritics should become visible as the user is typing and be removed from the screen as soon as the characters are removed.


Reproducible: Always


User Profile Reset: No



Additional Info:
Comment 1 vaaydayaasra 2018-08-30 13:55:34 UTC
Created attachment 144556 [details]
Writer view as the user is typing
Comment 2 vaaydayaasra 2018-08-30 13:56:23 UTC
Created attachment 144557 [details]
Writer view after the screen has changed
Comment 3 vaaydayaasra 2018-08-30 13:56:58 UTC
Created attachment 144558 [details]
Writer view after removing the text
Comment 4 Jan-Marek Glogowski 2018-10-01 15:12:00 UTC
Created attachment 145298 [details]
Just an example image from master build
Comment 5 Jan-Marek Glogowski 2018-10-01 15:13:38 UTC
Created attachment 145299 [details]
The example document used for the screenshot
Comment 6 Jan-Marek Glogowski 2018-10-01 15:19:03 UTC
That image is from todays master…

And yes - those two selections is just one done with a single cursor.

Probably this should have been a new bug…

Version: 6.2.0.0.alpha0+
Build-ID: b0eab4b2d2761139ecf5191252dfa8005cd29508
CPU-Threads: 64; BS: Linux 3.16; UI-Render: Standard; VCL: x11; 
Gebietsschema: de-DE (de_DE.UTF-8); Calc: threaded
Comment 7 Buovjaga 2018-10-01 16:36:29 UTC
Repro.

Arch Linux 64-bit
Version: 6.2.0.0.alpha0+
Build ID: d357ea1d1ff95cb5ce2ee6b4828afa2484707256
CPU threads: 8; OS: Linux 4.18; UI render: default; VCL: gtk3_kde5; 
Locale: fi-FI (fi_FI.UTF-8); Calc: threaded
Built on 28 September 2018
Comment 8 Khaled Hosny 2018-10-01 22:34:37 UTC
We are probably clipping the drawn area at line height instead of font’s OS/2 table Win metrics, which is wrong IMO.
Comment 9 Khaled Hosny 2018-10-01 22:36:05 UTC
That some glyphs or parts of glyph can be outside ascender/descender is not unusual and is font specific. We shouldn’t be clipping based on line height either way.
Comment 10 Buovjaga 2018-10-03 15:29:55 UTC
(In reply to Khaled Hosny from comment #9)
> That some glyphs or parts of glyph can be outside ascender/descender is not
> unusual and is font specific. We shouldn’t be clipping based on line height
> either way.

So essentially the same issue as bug 99578 and bug 105346 ?
Comment 11 Khaled Hosny 2018-10-03 17:16:43 UTC
(In reply to Buovjaga from comment #10)
> (In reply to Khaled Hosny from comment #9)
> > That some glyphs or parts of glyph can be outside ascender/descender is not
> > unusual and is font specific. We shouldn’t be clipping based on line height
> > either way.
> 
> So essentially the same issue as bug 99578 and bug 105346 ?

Most likely yes, the same underlying issue.
Comment 12 Buovjaga 2018-10-03 17:37:52 UTC
Not completely confident, if we should close as dupe, so using See also for now.
Comment 13 QA Administrators 2019-10-04 03:05:54 UTC Comment hidden (obsolete)
Comment 14 vaaydayaasra 2019-10-07 15:46:20 UTC
Still reproducible on:

Version: 6.3.2.2
Build ID: libreoffice-6.3.2.2-snap1
CPU threads: 4; OS: Linux 4.15; UI render: default; VCL: gtk3; 
Locale: fi-FI (fi_FI.UTF-8); UI-Language: en-US
Calc: threaded