bugThe FreeType Project - Bugs: bug #47064, FT_Get_Advance() should respect...

 
 

bug #47064: FT_Get_Advance() should respect variations

Submitted by:  None
Submitted on:  Fri 05 Feb 2016 08:09:12 AM UTC  
 
Severity: 3 - NormalItem Group: Incorrect behaviour
Status: FixedPrivacy: Public
Assigned to: Werner LEMBERG <wl>Open/Closed: Closed
Planned Release: 2.6.3

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Fri 05 Feb 2016 11:52:41 AM UTC, comment #1:

Fixed in git, thanks.

Werner LEMBERG <wl>
Project AdministratorIn charge of this item.
Fri 05 Feb 2016 08:09:12 AM UTC, original submission:

Currently, FT_Get_Advance() does not respect variations. For example, with Apple's Skia.ttf font, FreeType correctly interpolates the glyph shapes including phantom points. However, FT_Get_Advance() always returns metrocs for the base font, without taking variations into account.

Here's a (pretty ugly, sorry) ad-hoc program to visualize the effect. If you click the shaping checkbox, it will call HarfBuzz for shaping, which in turn invokes FT_Get_Advance(). With the checkbox clicked, the glyphs are positioned as if all design axes were set to 1.0.
https://github.com/brawer/playground/tree/master/fonts/atm

For faster speed, it might be possible to implement a special 'gvar' decoder in FreeType that only decodes the phantom points without loading the entire glyph.

-- Sascha

Sascha Brawer, -unavailable-

Anonymous

 

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    Follow 4 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Fri 05 Feb 2016 11:52:41 AM UTCwlStatusNone=>Fixed
      Assigned toNone=>wl
      Open/ClosedOpen=>Closed
      Planned ReleaseNone=>2.6.3

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