bugThe FreeType Project - Bugs: bug #39417, Vertical misalignment of plus and...

 
 

bug #39417: Vertical misalignment of plus and minus glyphs in various fonts

Submitted by:  Roman Odaisky <rdaysky>
Submitted on:  Sat 06 Jul 2013 08:20:24 PM UTC  
 
Severity: 3 - NormalItem Group: Incorrect behaviour
Status: Wont FixPrivacy: Public
Assigned to: Werner LEMBERG <wl>Open/Closed: Closed
Planned Release: None

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Sun 07 Jul 2013 05:13:17 AM UTC, comment #1:

This is an unfortunate side effect of how FreeType's auto-hinter works: It doesn't have the proper hinting info that the middle lines of `-' and `+' have to be aligned.

The concept of a `horizontal design axis' is something which is hard to manage since it usually is very near to the height of the lowercase letters, and too many global alignment zones makes the hinting worse. The solution would be that such an axis gets applied to a small set of glyphs only, but the auto-hinter doesn't support this.

You have to activate native TrueType hinting to get what you want.

Werner LEMBERG <wl>
Project AdministratorIn charge of this item.
Sat 06 Jul 2013 08:20:24 PM UTC, original submission:

In any reasonable font, the horizontal bar of the plus sign and the bar of the minus sign (U+2212) are at exactly the same height.

However, with many fonts these glyphs are not rendered in alignment at small sizes. For example, 9pt DejaVu Sans and Linux Libertine render like this for me: http://qwertty.com/tmp/pmvalign.png (source: http://qwertty.com/tmp/pmvalign.html)

What causes identical parts of the glyphs to be rendered differently?

fonts.conf:
<match target="font"><edit mode="assign" name="antialias"><bool>true</bool></edit></match>
<match target="font"><edit mode="assign" name="rgba"><const>rgb</const></edit></match>
<match target="font"><edit mode="assign" name="hinting"><bool>true</bool></edit></match>
<match target="font"><edit mode="assign" name="hintstyle"><const>hintslight</const></edit></match>
<match target="font"><edit mode="assign" name="lcdfilter"><const>lcddefault</const></edit></match>
<match target="font"><edit mode="assign" name="embeddedbitmap"><bool>false</bool></edit></match>

Roman Odaisky <rdaysky>

 

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  • -unavailable- added by wl (Posted a comment)
  • -unavailable- added by rdaysky (Submitted the item)
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    Follow 3 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Sun 07 Jul 2013 05:13:17 AM UTCwlStatusNone=>Wont Fix
      Assigned toNone=>wl
      Open/ClosedOpen=>Closed

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