[NTG-context] how to reset and switch fallbackfont?

28 Feb 2025

      hi,

As described in the title, how to reset fallbackfont?

I have created a number of Chinese typescripts and related fallbackfont (latin).

However, in the actual operation process, 
I found that if you want to switch different fallbackfont, 
you must change the bodyfont at the same time (\setupbodyfont).

The following is an example. 
How should I reset and switch to fallbackfont without changing the bodyfont?

%%%%%%%

\definefontfeature[zh][mode=node,script=hang,lang=zhs]

\startsetups fallbacks:reset
  \resetfontfallback[serifwhatever]
  \resetfontfallback[serifboldwhatever]
  \resetfontfallback[serifitalicwhatever]
  \resetfontfallback[serifbolditalicwhatever]
\stopsetups

\startsetups fallback:lm
 \definefontfallback[serifwhatever]          [lmroman10-regular]   [0x0000-0x0400][force=yes]
 \definefontfallback[serifboldwhatever]      [lmroman10-bold]      [0x0000-0x0400][force=yes]
 \definefontfallback[serifitalicwhatever]    [lmroman10-italic]    [0x0000-0x0400][force=yes]
 \definefontfallback[serifbolditalicwhatever][lmroman10-bolditalic][0x0000-0x0400][force=yes]
\stopsetups

\startsetups fallback:eb
 \definefontfallback[serifwhatever]          [ebgaramondregular]   [0x0000-0x0400][force=yes]
 \definefontfallback[serifboldwhatever]      [ebgaramondbold]      [0x0000-0x0400][force=yes]
 \definefontfallback[serifitalicwhatever]    [ebgaramonditalic]    [0x0000-0x0400][force=yes]
 \definefontfallback[serifbolditalicwhatever][ebgaramondbolditalic][0x0000-0x0400][force=yes]
\stopsetups

 \starttypescript [serif] [zhfont]
    \definefontsynonym [Serif]          [AdobeSongStd-Light]   [features=zh,fallbacks=serifwhatever]
    \definefontsynonym [SerifBold]      [AdobeHeitiStd-Regular][features=zh,fallbacks=serifboldwhatever]
    \definefontsynonym [SerifItalic]    [AdobeKaitiStd-Regular][features=zh,fallbacks=serifitalicwhatever]
    \definefontsynonym [SerifBoldItalic][AdobeHeitiStd-Regular][features=zh,fallbacks=serifbolditalicwhatever]
 \stoptypescript

 \starttypescript[myfont]
    \definetypeface[myfont][rm][serif][zhfont]
 \stoptypescript

 \usetypescript[myfont] 
 \starttext

 \setups{fallback:lm}
 \setupbodyfont[myfont,rm,12pt]
 fonts {\bf fonts} {\bi fonts} {\it fonts} % will be lm font
 \\\the\font

 \setups{fallbacks:reset}
 \setups{fallback:eb}
 fonts {\bf fonts} {\bi fonts} {\it fonts} % expected eb but lm
 \\\the\font

 \setups{fallbacks:reset}
 \setups{fallback:eb}
 \setupbodyfont[myfont,rm,12pt]%% any other chinese font, and change to eb
 fonts {\bf fonts} {\bi fonts} {\it fonts}
 \\\the\font
 \stoptext
%%%%

best wishes,
autumnus