Compress integral symbol \int horizontally

Question

As the title suggests, is there a way to adjust the width of the integral symbol by compressing it in the horizontal direction? Adjustbox only seems to allow me to adjust the height, and the width does not change.

Answer 1

Use \resizebox.

\documentclass{article}
\usepackage{graphicx}
\begin{document}
$\displaystyle\int$
\resizebox{.5\width}{\height}{$\displaystyle\int$}
$\displaystyle\int$
\end{document}

or use an upright integral symbol which is naturally narrower, e.g. from eulervm.

\documentclass{article}
\DeclareSymbolFont{eulargesymbols}{U}{zeuex}{m}{n}
\DeclareMathSymbol{\intop}{\mathop}{eulargesymbols}{"52}
\begin{document}
$\displaystyle\int$
\end{document}

Answer 2

Here I use scalerel package's \hstretch to compress the sign to 80, 60, and 40%, respectively. Unlike \resizebox, it automatically works across math styles. I have embodied it here as \varint[<scale>].

\documentclass{article}
\usepackage{scalerel}
\newcommand\varint[1][.8]{\mathrel{\hstretch{#1}{\int}}}
\begin{document}
\[
\int_0^x \varint_{\!\!\!0}^x \varint[.6]_{\!\!0}^x  \varint[.4]_{\!0}^x 
\]
\[
\scriptstyle \int \varint \varint[.6] \varint[.4]
\]
\end{document}

See this related question, Integral Sign $\int...$, for integral signs that are naturally more vertical and less slanted; in the Russian style, as it were.