Bug 89393

Summary: Lack of kerning between r and n in DejaVu Sans Oblique
Product: DejaVu Reporter: info
Component: SansAssignee: Deja Vu bugs <dejavu-bugs>
Status: ASSIGNED --- QA Contact:
Severity: minor    
Priority: medium CC: fitojb
Version: unspecified   
Hardware: Other   
OS: Linux (All)   
i915 platform: i915 features:
Attachments: Screen shot in Libre Office Writer, 4.2.7, 95% zoom, of the word 'Kernersee'. Note the fusion of the letters r and n.
Comparison image

Description info 2015-03-02 15:44:38 UTC
Created attachment 113922 [details]
Screen shot in Libre Office Writer, 4.2.7, 95% zoom, of the word 'Kernersee'. Note the fusion of the letters r and n.

In DejaVu Sans Oblique, it seems there is too small kerning between the letters r and n, making this combination look like an m.

This bug was originally reported at Openstreetmap: https://github.com/gravitystorm/openstreetmap-carto/issues/1335

However, the issue is not unique to Openstreetmap, and can also be reproduced in Libre Office Writer.

Is there anything that can be done about this?

Attached: screen shot in Libre Office Writer, 4.2.7, 95% zoom, of the word 'Kernersee'. Note the fusion of the letters r and n.
Comment 1 info 2015-03-02 15:46:07 UTC
Attachment doesn't seem to be recognized as picture. Se here for the picture: https://cloud.githubusercontent.com/assets/5251909/6444082/28edfa40-c0f3-11e4-999e-2f79e12e43fc.png
Comment 2 nocturnaldreamer 2015-03-04 14:29:51 UTC
The bearings may be incorrect since the gap between e and r appear too wide. I'll check this by the end of the week.
Comment 3 nocturnaldreamer 2015-03-08 23:04:58 UTC
Created attachment 114139 [details]
Comparison image

Based on the screenshot the issue occurs at 23 ppem. I can't reproduce the issue with LibreOffice on Windows, so this might be an issue with the delta hints (which are afaik ignored on Windows if ClearType is activated). Compared to the Windows rendering the r is shifted by one pixel to the right (see comparison image).

Unfortunately I'm not familiar with delta hints, so I can't fix this.
Comment 4 info 2015-03-08 23:11:59 UTC
Thanks for checking. Did you try different zoomlevels in OpenOffice?

I'm no expert, but to me it looks that in your attachment, the r and n are too close even in the second line?

My screenshot was generated in Linux Mint 17 (Qiana) with Cinnamon, kernel 3.13.0-30-generic. Please let me know if you need more information.
Comment 5 nocturnaldreamer 2015-03-09 00:06:33 UTC
Hi, I did not see the part about zoom level earlier. This is an irregular use case that won't be fixed. It is practically impossible for letters to look good at every fractional size.

However I looked at the original OSM bug report, the real use case seems to be at 13 ppem. There are three px between the stem of r and the left leg of n and also three px between the legs of n. So r and n are possibly too close (this can also be reproduced on Windows). In OSM the problem is exacerbated by the outlines and the color choice.

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