On Tue, Oct 16, 2018 at 07:48:41PM +0200, Pablo Rodriguez wrote:
I cannot claim that I understand his explanation, but it seems that there is something about the em quad
The em quad has the same width as the font size, that’s correct. But it still doesn’t mean that any part of any glyph in the font has that length. It’s really a tautology, actually: if you take a font at size, say, 12pt, then the em space is 12pt wide. That’s the definition (at least in the TeX world). It’s less clear what you’re trying to do next:
\setupframed [offset=none, framecolor=red, rulethickness=0.01pt, width=12pt, height=12pt]
\starttext \startTEXpage[offset=1em] \framed{M} \framed{\tfxx M} \framed{\tfd M} \stopTEXpage \stoptext
What are you trying to demonstrate with this? If you change the size of the font, obviously the glyphs have different sizes. The initial size at \starttext is 12pt, then \tfxx and \tfd change the sizes, to 8pt and 20.736pt respectively. Hence the former looks quite small in the box, and the latter looks very large. All that’s perfectly normal, and since you’re not changing the font, or even the glyph, it’s not a good illustration of the points raised in your initial email.
The issue with units per em is something I didn’t understand.
That’s irrelevant for you as a font user. Don’t worry about it. Best, Arthur