Increase vertical row spacing in booktabs, but keep content vertically centered

Question

I am using tabularx + booktabs and I am looking for a way to increase the vertical spacing between rows, but at the same time keep the content of each row vertically centered.

I have tried to use arraystretch but, as shown in this answer, the additional space is not evenly distributed; more space tends to be added to the 'top' of the row than to the bottom.

I would like to find a solution that affects all rows in all tables of a document (which has dozens of long tables) without having to manually insert spaces, struts, etc. for each individual row.

More details: I am not using midrules to separate individual rows. I am relying on \rowcolor to differentiate rows.

Here's a MWE taken from egreg's answer:

\documentclass{article}
\usepackage{tabularx,booktabs}
\usepackage{lipsum} % just for the example

\usepackage[table]{xcolor}
\rowcolors{2}{gray!10}{white}

\begin{document}

\noindent
\begin{tabularx}{\textwidth}{@{}llX@{}}
\toprule
A & B & \centering C \tabularnewline
\midrule
1 & 2 & \lipsum*[2] \\

1 & 2 & \lipsum*[2] \\
\bottomrule
\end{tabularx}

\bigskip

\noindent
\begin{tabularx}{\textwidth}{@{}llX@{}}
\toprule
A & B & \centering C \tabularnewline
\midrule
1 & 2 & \lipsum*[2] \\

1 & 2 & \lipsum*[2] \\
\bottomrule
\end{tabularx}

\end{document}

Is this possible?

Answer 1

It seems to me that you could be helped if there was a \extrarowdepth parameter similar to \extrarowheight. The package tabu has that. Unfortunately it doesn't seem to work with multiline cells. So I wrote a small package that does just that: add an \extrarowdepth parameter.

It works even when tabu is loaded, but not for the tabu environment. It just shares the its \extrarowdepth length parameter in that case, just to avoid a conflict.

Here it is:

%% extrarowdepth.sty
%% Copyright (C) 2016 by Piet van Oostrum <piet@vanoostrum.org>
%% This package defines a new length variable \extrarowdepth, similar to
%% \extrarowheight in the `array' package.
\NeedsTeXFormat{LaTeX2e}
\ProvidesPackage{extrarowdepth}%
           [2016/11/225 v1.0 Define \string\extrarowdepth\space for arrays and tabulars]%
% Prevent a clash with tabu, or other packages that also define \extrarowdepth.
\AtBeginDocument{%
  \ifdefdimen\extrarowdepth{} % \extrarowdepth already defined as a length
  {\ifdef\extrarowdepth % if it is defined but not a length, we have an error
    {\PackageError{extrarowdepth}{Cannot define length \string\extrarowdepth}
      {There is already a \string\extrarowdepth\space and it is not a length parameter.}}
    {\newlength\extrarowdepth\setlength\extrarowdepth{0pt}}}%
  \newlength\@temprowdepth}

\RequirePackage{array}
\RequirePackage{etoolbox}

\patchcmd{\@array}{\setbox \@arstrutbox \hbox{\vrule \@height \arraystretch \@tempdima \@depth \arraystretch \dp \strutbox \@width \z@}}
{\@temprowdepth  \dp \strutbox \advance \@temprowdepth by\extrarowdepth \setbox \@arstrutbox \hbox{\vrule \@height \arraystretch \@tempdima \@depth \arraystretch \@temprowdepth \@width \z@}}
{\PackageInfo{extrarowdepth}{\string\extrarowdepth\space added to the array package}}
{\PackageWarning{extrarowdepth}{Failed to include \string\extrarowdepth\space in the array package}}
\let\@@array\@array

And here is an example how to use it.

\documentclass{article}
\usepackage{tabularx,booktabs}
\usepackage{lipsum} % just for the example
\usepackage{extrarowdepth}

\usepackage[table, svgnames]{xcolor}
\rowcolors{2}{lightgray!30!Lavender}{white}

\begin{document}

\setlength\extrarowheight{4pt}
\setlength\extrarowdepth{4pt}

\noindent
\begin{tabularx}{\textwidth}{@{}llX@{}}
\toprule
\rowcolor{white}
A & B & \centering C \tabularnewline
\midrule
1 & 2 & \lipsum*[2] \\
1 & 2 & \lipsum*[2] \\
1 & 2 & \lipsum*[2] \\
\bottomrule
\end{tabularx}

\end{document}

Answer 2

Act on the parameters \aboverulesep and \belowrulesep:

\documentclass{article}
\usepackage{tabularx,booktabs}
\usepackage{lipsum} % just for the example

\begin{document}

\noindent
\begin{tabularx}{\textwidth}{@{}llX@{}}
\toprule
A & B & \centering C \tabularnewline
\midrule
1 & 2 & \lipsum*[2] \\
\midrule
1 & 2 & \lipsum*[2] \\
\bottomrule
\end{tabularx}

\bigskip

\setlength{\aboverulesep}{10pt}
\setlength{\belowrulesep}{10pt}

\noindent
\begin{tabularx}{\textwidth}{@{}llX@{}}
\toprule
A & B & \centering C \tabularnewline
\midrule
1 & 2 & \lipsum*[2] \\
\midrule
1 & 2 & \lipsum*[2] \\
\bottomrule
\end{tabularx}

\end{document}

With colored rows, you can insert \addlinespace:

\documentclass{article}
\usepackage{tabularx,booktabs}
\usepackage{lipsum} % just for the example

\usepackage[table]{xcolor}

\rowcolors{2}{gray!10}{white}

\begin{document}

\noindent
\begin{tabularx}{\textwidth}{llX}
\toprule
\rowcolor{white}
A & B & \centering C \tabularnewline
\midrule
1 & 2 & \lipsum*[2] \\ \addlinespace
1 & 2 & \lipsum*[2] \\ \addlinespace
1 & 2 & \lipsum*[2] \\
\bottomrule
\end{tabularx}

\end{document}

Answer 3

A simple solution would be to use the cellspace package, which defines minimal spacing at the top and bottom of cells in columns with specifier prefixed with the letter S. Unfortunately, when applied to the X column type and `colortbl is loaded, it doesn't work any more, for some reason.

So I had to use a work-around: cellspace is used for the first column, and at the end of an X cell, I automatically add an invisible rule under the base line with >{}.

\documentclass{article}
\usepackage{tabularx,booktabs}
\usepackage{lipsum} % just for the example
\usepackage{bigstrut}
\usepackage[table, svgnames]{xcolor}
\usepackage{cellspace}
\setlength\cellspacetoplimit{1.5ex}
\setlength\cellspacebottomlimit{1.5ex}
\rowcolors{2}{lightgray!30!Lavender}{white}

\begin{document}

\noindent
\begin{tabularx}{\textwidth}{Sl l X <{\rule[-2ex]{0pt}{0ex}}}%
\toprule
\rowcolor{white}
A & B &\multicolumn{1}{c}{C} \tabularnewline
\midrule
1 & 2 & \lipsum*[2] \\ %
1 & 2 & \lipsum*[2] \\ %
1 & 2 & \lipsum*[2] \\
\bottomrule
\end{tabularx}

\end{document}