为什么无论我如何指定列，此表的左列都会垂直对齐到底部？

Question

本文档生成的表格与我想要的大致相同...只是我无法让左侧列中的文本垂直居中对齐。我真正想要的是让该列中的文本垂直居中对齐，水平居中对齐。

我查找了有关这方面的资料，但都表明

• 默认情况下，内容将顶部对齐
• 使用array包并指定使用列m{width}将产生一个中间对齐的列。

但我得到的输出似乎并没有证实这一点。发生了什么？

\documentclass[a4paper]{amsart}

\usepackage{array, tikz}
\usetikzlibrary{arrows}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\begin{document}

\tikzset{
    s/.style = { font = \ttfamily,
                 anchor = west
                 },
    r/.style = { draw,
                 shape = rectangle,
                 minimum width = 6mm,
                 minimum height = 6mm,
                 font = \ttfamily
                 },
    c/.style = { draw,
                 shape = circle,
                 minimum width = 6mm,
                 minimum height = 6mm,
                 font = \ttfamily
                 },
    arrow/.style = { ->,
                     > = angle 60,
                     thick
                     }
}
\newcommand{\extraSpaceAbove}{\node at (0, -0.4) {\phantom{x}};}
    % Hack alert!
\begin{center}
    \setlength{\tabcolsep}{4mm}
    \renewcommand{\arraystretch}{1.4}
    \begin{tabular}{m{30mm}|l}
             \multicolumn{1}{c|}{Statement}
           & \multicolumn{1}{c}{Symbol table}
        \\ \hline
             \tt{local a := 2;}
           & \begin{tikzpicture} [x = 17.5mm, y = -7.5mm]
                 \extraSpaceAbove
                 \node [r] (a)    at (0, 0) {a};
                 \node [c] (aval) at (1, 0) {2};
                 \draw [arrow] (a.east) -- (aval);
             \end{tikzpicture}
        \\ \hline
             \tt{local b := 3;}
           & \begin{tikzpicture} [x = 17.5mm, y = -7.5mm]
                 \extraSpaceAbove
                 \node [r] (a)    at (0, 0) {a};
                 \node [r] (b)    at (0, 1) {b};
                 \node [c] (aval) at (1, 0) {2};
                 \node [c] (bval) at (1, 1) {3};
                 \draw [arrow] (a.east) -- (aval);
                 \draw [arrow] (b.east) -- (bval);
             \end{tikzpicture}
    \end{tabular}
\end{center}

\end{document}

Answer 1

左侧的文字是垂直居中对齐：就 TeX 而言，tikzpicture右列只是一行高文本，并且两列的基线正确对齐。

要使左侧的文本在视觉上垂直对齐，您可以使用 选项baseline，tikzpicture它告诉 TikZ 中的哪个 y 坐标tikzpicture应对应于周围文本的基线。 在您的情况下，baseline=(current bounding box.center)几乎可以工作，但它将左列的基线与 的中心对齐tikzpicture，而不是将左列的中心与 的中心对齐tikzpicture。 您可以使用baseline={($(current bounding box.center)+(0,-0.5ex)$)}，它使用calc库来计算低于中心 0.5ex 的坐标。

附注：\extraSpaceAbove您不应使用命令，而应使用\path [use as bounding box]语法（或等效简写\useasboundingbox）来重新定义边界框。要在图片顶部和底部添加 1ex，请\useasboundingbox (current bounding box.north west) ++(0,1ex) (current bounding box.south east) ++(0,-1ex);在 的末尾使用tikzpicture。

\documentclass[a4paper]{amsart}

\usepackage{array, tikz}
\usetikzlibrary{arrows,calc}

\begin{document}

\tikzset{
    s/.style = { font = \ttfamily,
                 anchor = west
                 },
    r/.style = { draw,
                 shape = rectangle,
                 minimum width = 6mm,
                 minimum height = 6mm,
                 font = \ttfamily
                 },
    c/.style = { draw,
                 shape = circle,
                 minimum width = 6mm,
                 minimum height = 6mm,
                 font = \ttfamily
                 },
    arrow/.style = { ->,
                     > = angle 60,
                     thick
                     }
}
\begin{center}
    \setlength{\tabcolsep}{4mm}
    \renewcommand{\arraystretch}{1.4}
    \begin{tabular}{m{30mm}|l}
             \multicolumn{1}{c|}{Statement}
           & \multicolumn{1}{c}{Symbol table}
        \\ \hline
             \ttfamily local a := 2;
           & \begin{tikzpicture} [x = 17.5mm, y = -7.5mm, baseline={($(current bounding box.center)+(0,-0.5ex)$)}]
                 \node [r] (a)    at (0, 0) {a};
                 \node [c] (aval) at (1, 0) {2};
                 \draw [arrow] (a.east) -- (aval);
                 \useasboundingbox (current bounding box.north west) ++(0,1ex) (current bounding box.south east) ++(0,-1ex);
             \end{tikzpicture}
        \\ \hline
             \ttfamily local b := 3;
           & \begin{tikzpicture} [baseline={($(current bounding box.center)+(0,-0.5ex)$)},x = 17.5mm, y = -7.5mm]
                 \node [r] (a)    at (0, 0) {a};
                 \node [r] (b)    at (0, 1) {b};
                 \node [c] (aval) at (1, 0) {2};
                 \node [c] (bval) at (1, 1) {3};
                 \draw [arrow] (a.east) -- (aval);
                 \draw [arrow] (b.east) -- (bval);
                 \useasboundingbox (current bounding box.north west) ++(0,1ex) rectangle (current bounding box.south east) ++(0,-1ex);

             \end{tikzpicture}
    \end{tabular}
\end{center}

\end{document}