Windows Font Settings

[Bhikkhu Pesala]

I still don't understand how to calculate the Windows Font Setting for TypoAscender, TypoDescender, TypoLineGap, WinDescender and WinDescender to get the right default leading for my fonts.

How does one ensure that a 10 point font defaults to 12 point line spacing in Applications?

How does one ensure that leading doesn't change when you mix italics or bold with the regular font?

I have read and reread the help file, but it doesn't answer my question. It just says "The suggested usage for TypoDescender is that it be used in conjunction with unitsPerEm to compute a typographically correct default line spacing." But it doesn't say how to calculate it.

[Bhikkhu Pesala]

I have tried reading the relevant links on Microsoft's Typography page, and it seems that one should change TypoLineGap to make the total add up right.

TypoAscender + TypoDescender + TypoLineGap = units/em * 120%

So for 1000 units/em this should add up to 1200. Theoretically, this should give a default line spacing of 12 points for a 10 point font.

For a 2048 units/em font the value should be 2458

However, this does not work in the real world of Page Plus DTP.