如何去除changepage包中的adjustwidth产生的垂直空间

Question

考虑这个最小的例子：

\documentclass{article}

\usepackage[utf8]{inputenc}
\usepackage{changepage}

\newenvironment{testenvironment}[2]{
    \textbf{#1} \textbf{#2}
    
    % \vspace*{-6pt} % <--- this is a workaround to fix the vertical space generated by adjustwidth
                     %      but it creates another vertical space problem if adjustwidth has contents
    \begin{adjustwidth}{8pt}{8pt} % <--- this adds a vertical space
}
{
    \end{adjustwidth}
}

\begin{document}

\begin{testenvironment}{Column1}{Column2}
\end{testenvironment}

\begin{testenvironment}{Column1}{Column2}
\end{testenvironment}

\end{document}

它生成了以下内容：

请注意，两行之间有明显的垂直间距。如果我注释环境adjustwidth（即\begin{adjustwidth}{8pt}{8pt}和\end{adjustwidth}），那么它会删除额外的垂直间距。但我想使用adjustwidth没有垂直间距的功能。上面的注释行adjustwidth（\vspace*{-6pt}）是删除垂直间距的变通方法，但如果adjustwidth里面有文本（即\begin{testenvironment}{Column1}{Column2} hello \end{testenvironment}），它会产生另一个垂直间距问题。

那么如何去除产生的多余垂直空间呢adjustwidth？

Answer 1

\baselineskip如果环境以垂直模式结束（例如，如果它是空的），您可以删除其中一个空间

\documentclass{article}

% not needed in current latex \usepackage[utf8]{inputenc}
\usepackage{changepage}

\newenvironment{testenvironment}[2]{% dont forget eol
    \textbf{#1} \textbf{#2}%
    \begin{adjustwidth}{8pt}{8pt}% <--- this adds a vertical space
}
{%
\ifvmode\mbox{}\par\nobreak\vspace{-\baselineskip}\fi
    \end{adjustwidth}%
}
    
\begin{document}

\begin{testenvironment}{Column1}{Column2}%
\end{testenvironment}


\begin{testenvironment}{Column1}{Column2}
testenvironment % no extra space with added text line
\end{testenvironment}

\begin{testenvironment}{Column1}{Column2}
testenvironment % no extra space with added text line

\end{testenvironment}

\begin{testenvironment}{Column1}{Column2}
testenvironment % no extra space with added text line
\end{testenvironment}

\begin{testenvironment}{Column1}{Column2}
testenvironment % no extra space with added text line

\end{testenvironment}

\end{document}

Answer 2

需要考虑以下两种情况：

% adjustprob.tex  Modified MWE from SE 559287

\documentclass{article}

\usepackage[utf8]{inputenc}
\usepackage{changepage}

\newenvironment{testenvironment}[2]{
    \textbf{#1} \textbf{#2}
    \begin{adjustwidth}{8pt}{8pt} % <--- this adds a vertical space
}
{
    \end{adjustwidth}%
}
    
\begin{document}

\begin{testenvironment}{Column1}{Column2}
% \mbox{ } % doesn't work for some reason
\end{testenvironment}
\vspace{-1em} % remove space after the environment

\begin{testenvironment}{Column1}{Column2}
testenvironment % no extra space with added text line
\end{testenvironment}

\begin{testenvironment}{Column1}{Column2}
testenvironment % no extra space with added text line
\end{testenvironment}

\end{document}

当添加额外的文本时，testenvironment没有额外的垂直空间。如果没有额外的文本，那么就会有额外的垂直空间，可以通过将\vspace{-1em} after thetestenvironment` 结尾删除。

我不知道为什么\mbox{}不将其视为额外的不可见文本。