Advanced Font Metrics in FontLab

Font file metrics can be stored in one of two tables, [OS/2] or [hhea] tables. Most of programs and operating systems use these tables and FontLab Studio can calculate the metrics according to the system recommendations, However, some type designers faced a problem with ascender and descender brushing up and also in adjusting the line gap when lines of type are set in a new font.  So, you need to be careful If you want to customize your values. Go to FontLab and From File -> Select: File Info.

From the menu Select: TrueType-Specific metrics.

Here is a description of each metrics value:

– Typo Ascender: is a typographically correct for ascender value. It is the top line of lowercase characters ‘b’.

– Typo Descender: is a typographically correct for descender value. It is the bottom line of lowercase characters ‘p’.

– Typo Line Gap: is a distance between bottom line of the upper line of text and top line of the lowerline of text.

– WinAscent: defines the topmost line of all important characters in the font.

– WinDescent: defines the lowest line of all “normal” characters.

– Ascender: is used by the Mac OS to define the topmost position of all important glyphs as WinAscent value.

– Descender: “If there are any pixels below this line the glyph will be squashed in the vertical direction to match metrics defined by the Ascender and Descender parameters.”

– Line Gap: “is used by the Mac OS to compensate Ascender and Descender values and calculate the correctdistance between baselines of the text.”



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    2 Responses to “Advanced Font Metrics in FontLab”

    1. SpideRaY says:

      Great post I’ve often wondered how to change the Typo Line Gap be care though I can cause problems if you reduce this too much. !!


    2. Martin B. Brilliant says:

      You write that WinAscent and WinDescent refer to “important” and “normal” characters. But the FontForge documention says these parameters are actually used as clipping levels and anything outside their range will be cropped, so they should be set from the largest possible ascent and descent, not just the “normal” values. I am confused. See http://fontforge.github.io/en-US/documentation/interface/fontinfo/

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