Bug TTX/fonttools: glyph position shifted

[supertype.de]

Hi,

After editing my ttf with TTX I found that the resulting ttf was faulty:

• Glyphs without nodes on the outer extreme (so it appeared) were shifted to the right
• Metrics stayed intact

The attached screenshot shows this shift in the glyphs “u” and “U”.

• Black letters: original ttf
• Pink letters: ttf generated from TTX (with edited nameIDs)

Thanks

Martin

[Cosimo Lupo]

You say your font contains glyphs without nodes at the outer extreme. 

Can you try to compile your edited ttx file using the -b option and see if that makes any difference?

From ttx --help:

> -b     Don't recalc glyph bounding boxes: use the values in the TTX file as-is.

How was the original TTF built? Did you build with fontmake? Or did you export the source from a font editor? If so which one?

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[supertype.de]

Hi Cosimo,

The -b does work, thanks.

Font was generated with with RoboFont 3.5

I was not aware that I have to set a an option for TTX to not do this. From my perspective that seems counter intuitive for there a so many cases where this can go wrong. Using TTX with any font with rounded corners for example would cause many unwanted shifts of glyphs unless -b is set. I do remember discussions about how to calculate the bounding box but I was not aware that it would be desirable to automatically change anything in a font that works, that could potentially cause such flawed results. What is the advantage?

Best,

Martin

[Paul van der Laan]

Another strategy:

Whenever I need to edit particular data with TTX I always dump the table in question only:

$ ttx -t name myfont.ttf

After editing I can merge that table back into the font using:

$ ttx -m myfont.ttf nametable.ttx

That way only the table in question will be (de)compiled and nothing else.

-Paul

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[Cosimo Lupo]

Could you file an issue over at http://github.com/fonttools/fonttools with a minimal test font that reproduces this?

thank you

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[Cosimo Lupo]

It might be that the way Robofont and FontTools calculate the glyf bounding boxes is different in the case of glyphs without nodes at extrema, but this is just a guess

[Martin Wenzel]

Cosimo, Paul,

Thanks for your feedback, much appreciated.

Best

Martin

supertype.de

Martin Wenzel +49 1520 3545 006

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