bugThe FreeType Project - Bugs: bug #19270, Wrong width for bitmap character...

 
 

bug #19270: Wrong width for bitmap character in TrueType font

Submitted by:  Giuseppe Bilotta <oblomov>
Submitted on:  Sat 10 Mar 2007 12:36:16 AM UTC  
 
Severity: 3 - NormalItem Group: Incorrect behaviour
Status: InvalidPrivacy: Public
Assigned to: Werner LEMBERG <wl>Open/Closed: Closed
Planned Release: None

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Sun 11 Mar 2007 01:33:34 AM UTC, comment #6:

Well, I used FontForge to inspect the font, not to make actual changes. I only noticed that it wouldn't let me set the width from the bitmap editor.

I've tried using the MS-provided tools http://www.microsoft.com/typography/tools/tools.htm to inspect the font, and the info I found about the bitmap A at 16ppem is the following:

Glyph 66 Metrics: H:0b W:08 X:00 Y:0a A:00
Image: 00 18 3C 66 66 66 7E 66 66 66 00

so it would seem that even though the width is properly set, the advanceWidth for the bitmap is set to 0, which is probably a bug in Fontlab. I'll pass the info over to the font developer.

Thanks for your assistance.

Giuseppe Bilotta <oblomov>
Sat 10 Mar 2007 06:11:40 PM UTC, comment #5:

Please contact the fontforge-devel list. George can
surely help.

Werner LEMBERG <wl>
Project AdministratorIn charge of this item.
Sat 10 Mar 2007 08:32:31 AM UTC, comment #4:

Oh yes, now I see.

The font author suggests that this is probably because Fontlab exports the bitmap data in Format 5, which according to http://www.microsoft.com/OpenType/OTSpec/ebdt.htm does not contain actual metric data, so that the global info can be used.

This might explain why FontForge won't allow me to manually set the width for the bitmap stroke, but I'm not expert in font formats nor in FontForge used. Can you confirm or suggest an alternative?

Giuseppe Bilotta <oblomov>
Sat 10 Mar 2007 06:01:10 AM UTC, comment #3:

Look at the 16ppem stroke, and you can see that the
`A' does have a width of zero. (It's not really good
to see in fontforge, but compare this to other fonts
which have embedded bitmaps, say, a CJK font: two thin,
black vertical lines indicates the horizontal dimensions).

Werner LEMBERG <wl>
Project AdministratorIn charge of this item.
Sat 10 Mar 2007 01:56:48 AM UTC, comment #2:

When I load the font in FontForge I see a width of 80, and L and R Bearings of 10 for the letter A. Am I looking at the wrong values?

Giuseppe Bilotta <oblomov>
Sat 10 Mar 2007 01:06:52 AM UTC, comment #1:

I think FreeType is right. Using FontForge I can see
that the width of the `A' bitmap glyph is indeed zero.

Werner LEMBERG <wl>
Project AdministratorIn charge of this item.
Sat 10 Mar 2007 12:36:16 AM UTC, original submission:

Hello all,

the Fixedsys Excelsior font, version 3.01, available at http://www.fixedsysexcelsior.com/ has a bitmap version of the capital A (and only of that glyph) at 16ppem.

Freetype2 miscalculates the width of the corresponding character when using the bitmap version of it, as can be seen with ftview (screenshot attached). This has some really undesired effects such as the capital A just disappearing when using the given font at the given size in GTK+ programs (e.g. X-Chat).

Giuseppe Bilotta <oblomov>

 

(Note: upload size limit is set to 16384 kB, after insertion of the required escape characters.)

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  • -unavailable- added by wl (Posted a comment)
  • -unavailable- added by oblomov (Submitted the item)
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    Follow 5 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Sat 10 Mar 2007 01:06:52 AM UTCwlStatusNone=>Invalid
      Assigned toNone=>wl
      Open/ClosedOpen=>Closed
    Sat 10 Mar 2007 12:36:16 AM UTCoblomovAttached File-=>Added ftview-16-fixedsysex300.png, #12168
      Carbon-Copy-=>Added oblomov

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