paracolrule

paracolrule adds decorative separator rules to the LaTeX paracol package.

• Version: 0.1.0
• Date: 2026-08-22
• Author: Kosei Kawaguchi (a.k.a. KKTeX)
• License: LaTeX Project Public License 1.3c or later
• Repository: https://github.com/KKTeX/paracolrule
• Support: p.c.aces1056@gmail.com

It changes only the rule segments generated by paracol. Page breaking, spanning text, arbitrary column counts and widths, background painting, and per-gap colors remain under paracol's control.

Usage

\usepackage{xcolor}
\usepackage{paracolrule}

\setlength{\columnseprule}{1pt}
\colseprulecolor{blue!70!black}
\ParacolRuleSetup{
  style=dashed,
  dash-length=5pt,
  gap-length=3pt
}

\begin{paracol}{2}
  Main text
  \switchcolumn
  Commentary
\end{paracol}

Built-in styles are solid, dashed, dotted, and double. A custom renderer can be installed with \ParacolRuleSetRenderer{\YourMacro}; the renderer receives the adjusted rule-segment height as its only argument. Dashed and dotted styles place a mark at both ends of every segment and calculate one common interval for all intervening marks. They therefore reach the exact bottom without a visibly shortened or uneven final gap.

Rule extents follow multicolrule: extend-top and extend-bot use positive values to extend and negative values to shorten. expand sets both values; shift moves the rule without changing its length. With zero extensions, the decorated rule keeps the exact segment boundaries generated by paracol. Those boundaries belong to the column box, not to the visible ink of its first and last glyphs; no font-dependent correction is guessed.

TikZ custom rules follow the multicolrule convention:

\usepackage[tikz]{paracolrule}
\ParacolRuleSetup{
  custom-line={
    \draw[line width=1pt] (TOP) to[bend left=8] (BOT);
  }
}

The code runs inside a tikzpicture; (TOP) and (BOT) are the exact endpoints of each separator segment. TikZ support is also detected when tikz was loaded before paracolrule. A custom TikZ rule uses the normal \colseprulecolor; per-gap color overrides apply only to the built-in renderers because paracol reuses one separator box for every gap.

Compatibility

Version 0.1.0 is tested with paracol 1.37. Because paracol does not expose a public separator-rendering hook, this package verifies its two internal patch points at load time and fails loudly if they have changed.

Building

make test
make doc
make sample
make zip

The package source is maintained directly in paracolrule.sty. The manual is paracolrule-doc.tex, and the multi-page visual example is paracolrule-sample.tex.

License

LaTeX Project Public License 1.3c or later.