FiraMono: xAvgCharWidth should match the standard glyph advance

[jfkthame]

In FiraMono-Regular.otf, the OS/2 table includes

<xAvgCharWidth value="585"/>

although the standard width of the (monospaced) glyphs is 600. This should be changed so that it matches the actual glyphs.

It looks like Glyphs is calculating an average that includes the small number of zero-width glyphs in the font. This results in an average that is slightly less than the font's fixed glyph advance, but it's not helpful for client software - e.g. when using this value to determine the size of a text area that's supposed to be "80 characters wide".

The OpenType spec[1] actually specifies this: "The value for xAvgCharWidth is calculated by obtaining the arithmetic average of the width of all non-zero width glyphs in the font." (My emphasis.)

[1] http://www.microsoft.com/typography/otspec/os2.htm#acw

[schriftgestalt]

The value is generated by makeOTF that is used the generate most tables. I will check with Adobe why they do not follow the specs for this. I fixed it on my side.

[adrientetar]

@schriftgestalt Have you heard back from them?

[schriftgestalt]

I fixed it myself. The latest beta should set the correct value.

[adrientetar]

But is there an issue in Adobe’s toolset? If so, I think it should be fixed upstream.

[schriftgestalt]

I will fix it in the fdk Github.

[adrientetar]

Thanks! Cheers.