Vertical spaces above and below longtabu

Question

This is, in a way, a follow-up-question to New table-environment, spaces and enclosing { } in a new environment, which has already been answered conveniently by @egreg.

---

Please compile this MWE to see and follow the problem:

\documentclass[a4paper, 11pt]{scrbook}
\usepackage{blindtext}
\usepackage[cm]{fullpage}

\usepackage{tabu, longtable, booktabs}
\usepackage{caption}

\newenvironment{texttab}[1]%
        {\setlength{\topsep}{\baselineskip}%
            \begin{center} \tabulinesep=0.6ex%
            \begin{tabu} to 0.9\textwidth {#1} \toprule \rowfont{\bfseries}}
            {\end{tabu}%
        \end{center}}

\newenvironment{tabspaces}[1]%
    {\setlength{\topsep}{\baselineskip}%
        \begin{center} \tabulinesep=0.6ex%
            \begin{longtabu} to 0.9\textwidth {#1} \toprule \rowfont{\bfseries}}
            {\end{longtabu}%
        \end{center}}

\newenvironment{texttab*}[1]%
    {\setlength{\topsep}{\baselineskip}%
    \LTpre=0pt%
    \LTpost=0pt%
        \begin{center} \tabulinesep=0.6ex%
            \begin{longtabu} to 0.9\textwidth {#1} \toprule \rowfont{\bfseries}}
            {\end{longtabu}%
        \end{center}}

\begin{document}
\section{TEST}
\blindtext
%
\begin{texttab}{X[l,2] X[l,2] X[l,3]}
Test1   &   Test2   &   Test3 works fine  \\ \midrule
Test1   &   Test2   &   Test3 works fine  \\
Test1   &   Test2   &   Test3 works fine  \\ \bottomrule
\end{texttab}%
%
\blindtext
%
\begin{tabspaces}{X[l,2] X[l,2] X[l,3]}
Test1   &   Test2   &   Test3   \\ \midrule
Test1   &   Test2   &   Test3   \\
Test1   &   Test2   &   Test3   \\ \bottomrule
\end{tabspaces}%
%
\blindtext
%
\begin{texttab*}{X[l,2] X[l,2] X[l,3]}
Test1   &   Test2   &   Test3   \\ \midrule
Test1   &   Test2   &   Test3   \\
Test1   &   Test2   &   Test3   \\ \bottomrule
\end{texttab*}%
%
\blindtext
\end{document}

---

I created three new environments: texttab, tabspaces and texttab*. They implement tabus (not to be embedded in floating bodies) in the text. As a result of the question mentioned before I made two environments for either normal tabus (texttab) or longtabus (texttab*). tabspaces is just for demonstration-use.

Now, if you take a look at the tabspaces-environment (second table in the example), you see it produces way too much vertical space above and below the environment.

I tried to use the commands \LTpre=0pt and \LTpost=0pt(provided by the longtable-package) in the texttab*-environment - you see, there's still way too much space below!

Where does it come from and how do I get rid of it?

Note: \tabulinesep=0.6ex seems to affect those spaces! Nevertheless, removing it doesn't change the fact that the vertical spaces still differ from the ones in my (satisfying) texttab-environment.

Answer 1

The reason why setting \LTpre and \LTpost has no effect on the texttab* environment is because you reset them to 0pt in the definition of that environment. I removed those two lines and set some rough values globally that give similar spacing to that produced by texttab.

\documentclass[a4paper, 11pt]{scrbook}
\usepackage{blindtext}
\usepackage[cm]{fullpage}

\usepackage{tabu, longtable, booktabs}
\usepackage{caption}
\setlength{\LTpre}{0pt}\setlength{\LTpost}{-17pt}%

\newenvironment{texttab}[1]%
        {\setlength{\topsep}{\baselineskip}%
            \begin{center} \tabulinesep=0.6ex%
            \begin{tabu} to 0.9\textwidth {#1} \toprule \rowfont{\bfseries}}
            {\end{tabu}%
        \end{center}}

\newenvironment{tabspaces}[1]%
    {\setlength{\topsep}{\baselineskip}%
        \begin{center} \tabulinesep=0.6ex%
            \begin{longtabu} to 0.9\textwidth {#1} \toprule \rowfont{\bfseries}}
            {\end{longtabu}%
        \end{center}}

\newenvironment{texttab*}[1]%
    {\setlength{\topsep}{\baselineskip}%
        \begin{center} \tabulinesep=0.6ex%
            \begin{longtabu} to 0.9\textwidth {#1} \toprule \rowfont{\bfseries}}
            {\end{longtabu}%
        \end{center}}

\begin{document}
\section{TEST}
\blindtext
%
\begin{texttab}{X[l,2] X[l,2] X[l,3]}
Test1   &   Test2   &   Test3 works fine  \\ \midrule
Test1   &   Test2   &   Test3 works fine  \\
Test1   &   Test2   &   Test3 works fine  \\ \bottomrule
\end{texttab}%
%
\blindtext
%
\begin{tabspaces}{X[l,2] X[l,2] X[l,3]}
Test1   &   Test2   &   Test3   \\ \midrule
Test1   &   Test2   &   Test3   \\
Test1   &   Test2   &   Test3   \\ \bottomrule
\end{tabspaces}%
%
\blindtext
%
\begin{texttab*}{X[l,2] X[l,2] X[l,3]}
Test1   &   Test2   &   Test3   \\ \midrule
Test1   &   Test2   &   Test3   \\
Test1   &   Test2   &   Test3   \\ \bottomrule
\end{texttab*}%
%
\blindtext
\end{document}

---

Qrrbrbirlbel points out below that using \centering rather than the center environment is an option. My quick attempt is below. I did a bit of fiddling with \par's to avoid the lines above from being centered as well...I'm not sure if there's a better way to go about doing that. In any case, because of the different behaviour of tabu and longtabu I think you may have to fiddle with the spacing of the first environment to match the latter two or vice-versa.

\documentclass[a4paper, 11pt]{scrbook}
\usepackage{blindtext}
\usepackage[cm]{fullpage}

\usepackage{tabu, longtable, booktabs}
\usepackage{caption}

\newenvironment{texttab}[1]%
    {\par\bigskip\centering\tabulinesep=0.6ex%
     \begin{tabu} to 0.9\textwidth {#1} \toprule \rowfont{\bfseries}}
    {\end{tabu}\par\bigskip}

\newenvironment{tabspaces}[1]%
    {\par\centering\tabulinesep=0.6ex%
     \begin{longtabu} to 0.9\textwidth {#1} \toprule \rowfont{\bfseries}}
    {\end{longtabu}}

\newenvironment{texttab*}[1]%
    {\par\centering\tabulinesep=0.6ex%
     \begin{longtabu} to 0.9\textwidth {#1} \toprule \rowfont{\bfseries}}
    {\end{longtabu}}

\begin{document}
\section{TEST}
\blindtext

\begin{texttab}{X[l,2] X[l,2] X[l,3]}
Test1   &   Test2   &   Test3 works fine  \\ \midrule
Test1   &   Test2   &   Test3 works fine  \\
Test1   &   Test2   &   Test3 works fine  \\ \bottomrule
\end{texttab}%

\blindtext
%
\begin{tabspaces}{X[l,2] X[l,2] X[l,3]}
Test1   &   Test2   &   Test3   \\ \midrule
Test1   &   Test2   &   Test3   \\
Test1   &   Test2   &   Test3   \\ \bottomrule
\end{tabspaces}%
%
\blindtext
%
\begin{texttab*}{X[l,2] X[l,2] X[l,3]}
Test1   &   Test2   &   Test3   \\ \midrule
Test1   &   Test2   &   Test3   \\
Test1   &   Test2   &   Test3   \\ \bottomrule
\end{texttab*}%
%
\blindtext
\end{document}