[1 mod] Kerning: ſ (U+017F) [latin long s] colliding with following characters

Bug #682472 reported by adoa
12
This bug affects 1 person
Affects Status Importance Assigned to Milestone
Ubuntu Font Family
Low
Unassigned
fonts-ubuntu (Ubuntu)
Undecided
Unassigned

Bug Description

1. pango-view --font="Ubuntu 48" --markup --text='<span fallback="false"> fl ſl • fb ſb • fk ſk • fi ſi • ff ſſ</span>'

Rendered in 46pt Regular

Sample Glyphs: ſf ſſ ſk ſi

The kerning and spacing for the latin long s "ſ" is not consistent with the remaining text.

In particular, when ‘ſ’ is followed by an ascending letter, the two collide.

The hinting is also somehow different from small f. I think that is not intended, since for big sizes the upper part of f and ſ become nearly identical. At least the latter is intended, I think.

Mozilla/5.0 (X11; U; Linux x86_64; de; rv:1.9.2.12) Gecko/20101027 Ubuntu/10.10 (maverick) Firefox/3.6.12

Revision history for this message
adoa (adoa) wrote :

Automatic Screenshot

Revision history for this message
David Marshall (dave-daltonmaag) wrote : Re: [Bug 682472] [NEW] Kerning:ſ (U+017F) [latin long s] colliding with following charaters

A collision is normal, expected, and desirable for this style of font.
To manipulate the design or advance widths to avoid it would produce an
indistinct character or an unacceptable stroke rhythm. In theory we
could have a stylistic ligature, but it would look no different to the
two colliding characters.

Dave

Revision history for this message
Denis Moyogo Jacquerye (moyogo) wrote : Re: Kerning: ſ (U+017F) [latin long s] colliding with following charaters

Another solution would be a narrower long s glyph for these sequences.
The 'calt' OpenType GSUB feature would be appropriate, but considering it isn't applied by default by Pango in Latin script, you'd have to use 'ccmp' which is.

Revision history for this message
Paul Sladen (sladen) wrote :

The first three renderings look fine to me; although I'm wondering if the 'ſi' combination might benefit from a ligature to improve legibility?

adoa/Denis: have you hit this "in anger" yet... do you have the related sample text that it showed up in to see if it's a real-world issue?

Changed in ubuntu-font-family:
status: New → Confirmed
importance: Undecided → Low
milestone: none → 1.00
Revision history for this message
adoa (adoa) wrote :

Actually no, I was just playing around with the feedback tool. I really hardly ever see this letter in use but I thought it should have more or less consistent behavior with the ‘f’ since the letters are so similar. Furthermore I cannot think of any other character combination, that is meant to touch in the Ubuntu Font.

Revision history for this message
Denis Moyogo Jacquerye (moyogo) wrote : Re: [Bug 682472] Re: Kerning: ſ (U+017F) [latin long s] colliding with following charaters

On Sun, Nov 28, 2010 at 10:34 PM, Paul Sladen <email address hidden> wrote:
> The first three renderings look fine to me; although I'm wondering if
> the 'ſi' combination might benefit from a ligature to improve
> legibility?
That could work too.

> do you have the related
> sample text that it showed up in to see if it's a real-world issue?
"ſſ" http://fr.wikisource.org/wiki/Fables_%28La_Fontaine%29_orthographe_modernis%C3%A9e/Livre_III/14
"ſk" http://en.wikisource.org/wiki/The_Castle_of_Indolence/E
"ſi" and "ſf" http://fr.wikisource.org/wiki/Trait%C3%A9_de_la_nature,_de_la_culture_et_de_l%27utilit%C3%A9_des_pommes_de_terre

Try "foibleſſe auſſi baffe elle deſk kafka ſatiſfaction" at different size.
Looking at it, there seems to be a problem with long s and ascenders
being much tighter than "ff" and looking darker than "ll".
It would make sense to have a bit more space after the long s,
somewhere between what it has now and what's between f's main stem and
the next ascender. The current spacing is fine when followed by a
short glyph like e or a.

Btw, long s is sometimes as tall as f and sometimes shorter depending
on the font size.

Revision history for this message
Malcolm Wooden (malcolm-daltonmaag) wrote : Re: Kerning: ſ (U+017F) [latin long s] colliding with following charaters

This report could be extended to request an expansion of the standard ligature range to include :
fb, fh, fj, ffj, fk including the long s varients also.

description: updated
summary: - Kerning: ſ (U+017F) [latin long s] colliding with following charaters
+ [1 mod] Kerning: ſ (U+017F) [latin long s] colliding with following
+ characters
tags: added: uff-dmi
Changed in ubuntu-font-family:
milestone: 1.00 → 0.92-beta-test
Changed in ubuntu-font-family:
status: Confirmed → In Progress
description: updated
Revision history for this message
Matthew Paul Thomas (mpt) wrote :

Verified that this is fixed in a 0.84 test version.

Changed in ubuntu-font-family:
status: In Progress → Fix Committed
Adolfo Jayme (fitojb)
Changed in fonts-ubuntu (Ubuntu):
status: New → Triaged
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