Bug 17200 - tilde '~' becomes a straight line at small font sizes
Summary: tilde '~' becomes a straight line at small font sizes
Status: REOPENED
Alias: None
Product: DejaVu
Classification: Unclassified
Component: General (show other bugs)
Version: unspecified
Hardware: x86 (IA32) Windows (All)
: medium normal
Assignee: Deja Vu bugs
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Blocks:
 
Reported: 2008-08-19 03:19 UTC by Mark Tyndall
Modified: 2008-10-22 13:38 UTC (History)
1 user (show)

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i915 platform:
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Attachments
Tildes matrix over font, style and size (19.15 KB, image/png)
2008-08-19 03:19 UTC, Mark Tyndall
Details

Description Mark Tyndall 2008-08-19 03:19:56 UTC
Created attachment 18377 [details]
Tildes matrix over font, style and size

In Sans Condensed, Sans Light, Serif Condensed and (to a lesser extent) Serif, the tilde character '~' is rendered as a straight line, similar to an en or em-dash, at smaller font sizes (8-9 pt and below).

Sans and Sans Mono are rendered as curvy lines down to 6pt and 7pt respectively.

See attached screenshot, using version 2.26 (file dates all 26/07/2008).


Expected results:

To see a curvy tilde, which can't be confused for an en/em-dash, at smaller font sizes.
Comment 1 Ben Laenen 2008-08-19 03:34:15 UTC
Can you confirm that you're using FreeType's autohinter? It certainly looks to me like you do. Unfortunately we have no control over the autohinter so we can't fix those issues.
Comment 2 James Cloos 2008-08-19 13:00:35 UTC
> Can you confirm that you're using FreeType's autohinter?

He specified his OS as windows....
Comment 3 nocturnaldreamer 2008-08-21 18:26:08 UTC
Just tested this on Windows XP SP3, I get the same behavior. Since some fonts do work, so there must be some inconsistency with the hinting.
Comment 4 James Cloos 2008-08-23 08:58:50 UTC
Using (freetype built from CVS, dejavu from svn):

ftview -r 96 5 /usr/share/fonts/dejavu/*ttf

I can see the bug in:

Sans ExtraLight, Oblique, Book
Mono Bold, Oblique, Book, Book Oblique
Serif Book

Leaving off the -r 96 shows that 5pt at 96 dpi is 7 px/em.

Most ttf fonts seem to include a pointer to ignore the instructions at
less than 8 px/em or so (the GASP table, right?).  That would deal with
this on doze, at least.

Frankly, the font is barely legible at all at 7 px/em (he says, who used
to use 75dpi/lutRS10.pcf as his xterm/emacs font, back in the 80s and 90s;
young eyes do have their perks).  So I don't know how critical it is.

But the GASP entry (assuming Iā€™m remembering the right table) couldn't hurt.
Comment 5 Mark Tyndall 2008-08-27 03:28:56 UTC
(In reply to comment #4)
[...]
> Leaving off the -r 96 shows that 5pt at 96 dpi is 7 px/em.
> 
[...]
> Frankly, the font is barely legible at all at 7 px/em (he says, who used
> to use 75dpi/lutRS10.pcf as his xterm/emacs font, back in the 80s and 90s;
> young eyes do have their perks).  So I don't know how critical it is.

I'm more concerned about the faces which don't display well at the not-quite-so-minuscule sizes - Condensed and Light have problems at 7/8/9 pt.

(My particular use that triggered the behaviour is using 8pt Sans Condensed to display filenames in Windows Explorer.)
Comment 6 Denis Jacquerye 2008-08-27 03:43:06 UTC
(In reply to comment #5)
> I'm more concerned about the faces which don't display well at the
> not-quite-so-minuscule sizes - Condensed and Light have problems at 7/8/9 pt.

This is a serious issue but right now Condensed and Light aren't hinted so that's the problem. At these sizes, non hinted fonts are inappropriate. Hinted or bitmaps fonts would be suitable.

Comment 7 Actam 2008-10-20 02:15:36 UTC
With the font pack 2.21, windows word 2003 or OpenOffice 3.0 at 4 pt level they still look like little tildes.
Maybe it's just a low resolution and/or cleartype that makes them look strait lines...
Gian Luca Ruggero
Comment 8 Mark Tyndall 2008-10-22 13:38:10 UTC
So this is a regression then...

Note the version used when reporting this is 2.26, which is later than 2.21.

Re-opening


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