[comp.sys.amiga.tech] Algorithmic underlining

john13@garfield.MUN.EDU (John Russell) (01/02/89)

A couple of questions about the way underlining is performed by the text
functions:

I have some (smaller than 8 x 8) fonts which do not permit underlining (at
least when used with the console device and <esc>[4m is used to turn on
underline). The normal baseline for topaz 8 is 6. These other fonts have
baselines either equal to or 1 less than their height. What is the rule for
determining whether a font can be underlined? Is it possible any time the
baseline is less than or equal to (height - 2)? I'm looking for a pattern
to it, and I'm not sure if these non-underlinable fonts may break some
guideline, perhaps the rule is to set baseline = fontheight if no underline
is desired but the creators of some fonts have it wrong.

What is the exact method used for generating an underline for a character
with a descender? I used to think that a horizontal strip was simply XORed
but upon closer examination the descenders actually are left alone by a
break in the underline bar. Is there a way to predict exactly how the bar
will be generated?

This is in connection with TSnip 1.5 (1.4a is the one I recently sent Bob
Page), which deals with letters that are in inverse video and/or underlined...
except if the underlined letters have descenders :-(.

John
-- 
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