Change font size in verbatim and Verbatim using scaling

Question

This question is closely related to several other questions here, but I believe it hasn't been asked (or answered) exactly like this.

Is it possible to change the font size in verbatim and Verbatim using a scale parameter?

For example, I know I can do

\setmonofont[Scale=0.8]{Menlo}

to globally change \texttt. And from answers I've seen here I know I can change the font size in verbatim using

\makeatletter
\patchcmd{\@verbatim}
  {\verbatim@font}
  {\verbatim@font\small}
  {}{}
\makeatother

or adjust Verbatim using

\begin{Verbatim}[fontsize=\small]

But suppose I don't want to specify \small, but instead use a scale factor like 0.8. Can this be done? Is there also a way modify it for all Verbatim blocks as well?

I am using LuaLaTeX.

Answer 1

You can define a command for setting the font size to a fraction of the current font size.

\documentclass{article}
\usepackage{fontspec,xfp}
\usepackage{fancyvrb}

\setmonofont{Menlo}[Scale=MatchLowercase]

\makeatletter
\newcommand{\scalefont}[1]{%
  \edef\scale@fontsize{\fpeval{#1*\f@size}}%
  \edef\scale@fontbaselineskip{\fpeval{1.2*\scale@fontsize}}%
  \fontsize{\scale@fontsize}{\scale@fontbaselineskip}\selectfont
}
\makeatother

\begin{document}

This is normalsize with \texttt{monospaced text}
\begin{Verbatim}[fontsize=\scalefont{0.8}]
This is scaled 80%
\end{Verbatim}
Again normalsize
\begin{Verbatim}[fontsize=\scalefont{0.5}]
This is scaled 50%
\end{Verbatim}

\end{document}