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

[adoa]

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

[adoa (adoa)]

Automatic Screenshot

[David Marshall (dave-daltonmaag)]

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

[Denis Moyogo Jacquerye (moyogo)]

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.

[Paul Sladen (sladen)]

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?

[adoa (adoa)]

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.

[Denis Moyogo Jacquerye (moyogo)]

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.

[Malcolm Wooden (malcolm-daltonmaag)]

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.

[Matthew Paul Thomas (mpt)]

Verified that this is fixed in a 0.84 test version.

[Adolfo Jayme Barrientos (fitojb)]

This issue is back in the Type Network-issued release