Thank you, I'll try that later.

On Tue, May 31, 2022 at 9:42 AM Max Chernoff <mseven@telus.net> wrote:

> > Thanks Max that works perfectly! But It would still be useful if I could
> > change families inside a MPpage.
>
> Sure, but you'll need to store the x-heights first:
>
>      \starttexdefinition storexheight [#1]
>          % Placing the first use of \switchtobodyfont inside a group messes
>          % with the definitions, so we need to reset the font family
> manually.
>          \edef\oldfontclass{\fontclass}
>
>          \switchtobodyfont[#1]
>          \expandafter\newcount\csname #1_xheight\endcsname
>          \global\csname #1_xheight\endcsname=\numexpr 100 *
> \number\dimexpr1em\relax / \number\dimexpr1ex\relax \relax
>
>          \switchtobodyfont[\oldfontclass]
>      \stoptexdefinition
>
>      \starttexdefinition setxheight [#1][#2]
>          % Combining these two lines into one sometimes fails. No idea why.
>          \switchtobodyfont[#1]
>          \switchtobodyfont[\the\dimexpr#2 * \csname #1_xheight\endcsname /
> 100 \relax]
>      \stoptexdefinition
>
>      \storexheight[adventor]
>      \storexheight[pagella]
>      \storexheight[heros]
>
>      \starttext
>          \startMPpage
>              draw textext.origin("\setxheight[adventor][1cm]Hello!");
>
>              draw (0, 1cm) -- (6cm, 1cm);
>          \stopMPpage
>
>          \startMPpage
>              draw textext.origin("\setxheight[pagella][1cm]Hello!");
>
>              draw (0, 1cm) -- (6cm, 1cm);
>          \stopMPpage
>
>          \startMPpage
>              draw textext.origin("\setxheight[heros][6pt]Hello!");
>              draw textext.origin("\setxheight[heros][24pt]Hello!");
>
>              draw (0, 6pt) -- (6cm, 6pt);
>              draw (0, 24pt) -- (6cm, 24pt);
>          \stopMPpage
>      \stoptext
>
> It's pretty ugly code, but it seems to work alright.
>
> -- Max
>
>