Bug 127920

Summary:	Ligatures enforced even when character spacing is increased
Product:	LibreOffice	Reporter:	Angelos Skembris <a.skembris>
Component:	Writer	Assignee:	Not Assigned <libreoffice-bugs>
Status:	RESOLVED DUPLICATE
Severity:	normal	CC:	a.skembris, dgp-mail, xiscofauli
Priority:	medium
Version:	6.3.2.2 release
Hardware:	x86-64 (AMD64)
OS:	All
Whiteboard:
Crash report or crash signature:		Regression By:
Bug Depends on:
Bug Blocks:	71732
Attachments:	Document with two words in increased character spacing. One has pair kerning enabled, the other one does not.

Description Angelos Skembris 2019-10-02 09:18:25 UTC

Description:
I believe the "pair kerning" option is ignored for some (or all) fonts, resulting in poor visual results. E.g. for the Open Sans font, if you type "specifications" and increase character spacing, all spaces are increased except the space between "f" and "i", resulting in uneven letter spacing and a gap in the word. "f" and "i" remain attached to each other.  

Steps to Reproduce:
1.Write a word that possibly includes a kerned pair, like "specifications" (f-i, ti)
2.Select "Open Sans" font, "Calibri", "DejaVu Sans" or some other font (which possibly contains a kerning table
3.Right click on the word, select "Character -> Character", go to "position" tab, increase character spacing to e.g. 10pt. 

Actual Results:
The space between certain combinations like "f" and "i" remains the same even though other letters are spaced further apart. In "Calibri" font this also happens with "t" and "i". Clicking "Pair kerning" makes no difference to how the word is displayed. 

Expected Results:
Disabling pair kerning should result in all letters being evenly spaced (I guess it should be disabled anyway when character spacing is anything other than the default setting).


Reproducible: Always


User Profile Reset: No


OpenGL enabled: Yes

Additional Info:
Problem is present in both Windows and Linux versions. Tried 6.3.1 and 6.3.2 on Linux, 6.3.2 on Windows. Exporting to PDF results in the PDF having the same problem.

Comment 1 Xisco Faulí 2019-10-04 13:44:32 UTC

Thank you for reporting the bug. Please attach a sample document, as this makes it easier for us to verify the bug. 
(Please note that the attachment will be public, remove any sensitive information before attaching it. 
See https://wiki.documentfoundation.org/QA/FAQ#How_can_I_eliminate_confidential_data_from_a_sample_document.3F for help on how to do so.)

I have set the bug's status to 'NEEDINFO'. Please change it back to 'UNCONFIRMED' once the requested document is provided.

Comment 2 Angelos Skembris 2019-10-04 13:52:24 UTC

Created attachment 154760 [details]
Document with two words in increased character spacing. One has pair kerning enabled, the other one does not.

Comment 3 Dieter 2019-10-08 15:45:57 UTC

I'm not an expert, but I think, it's because ligatures are enabled. If you disable them (just type Calibri:-liga in font combobox) you recieve the desired result.

So for me not a bug, but I agree, that documentation about ligatures could be improved (I couldn't find anything about it).

=> RESOLVED NOTABUG

If you disagree, please change it back to UNCONFIRMED with a short reasoning.

Comment 4 Angelos Skembris 2019-10-08 16:37:12 UTC


*** This bug has been marked as a duplicate of bug 66819 ***

Comment 5 Angelos Skembris 2019-10-08 16:39:55 UTC

(In reply to Dieter Praas from comment #3)
> I'm not an expert, but I think, it's because ligatures are enabled. If you
> disable them (just type Calibri:-liga in font combobox) you recieve the
> desired result.
> 
> So for me not a bug, but I agree, that documentation about ligatures could
> be improved (I couldn't find anything about it).
> 
> => RESOLVED NOTABUG
> 
> If you disagree, please change it back to UNCONFIRMED with a short reasoning.

Thanks for looking into this, Dieter. From your comments, I saw there already is a bug report on this, so I marked it as a duplicate.