子标题：垂直图像对齐 - 传递图像高度

Question

我有两个外部图形，我想使用subcaption-package 的高度相同。为了获取第一个文件的高度，我使用\settoheight。在使用它的子图中，值设置正确。但是，当我离开子图时，值似乎设置为零。这是为什么？我怎样才能将图像高度从左侧子图传递到右侧子图？

---

平均能量损失

\documentclass{article}

\usepackage{graphicx}
\usepackage{subcaption}

\newlength{\figwidth}
\newlength{\figheight}
\newlength{\figdim}

\begin{document}

\begin{figure}[htbp]
  \begin{subfigure}{0.59\linewidth}
    % Length
    \setlength{\figwidth}{\linewidth}
    \setlength{\figheight}{5cm}
    \settoheight\figdim{\includegraphics[width=\figwidth,height=\figheight,keepaspectratio]{example-image-a}}
    \setlength{\figheight}{\figdim}
    % Figure
    \centering
    \includegraphics[width=\figwidth,height=\figheight,keepaspectratio]{example-image-a}
    \caption{\the\figdim, \the\figheight, left}%
    \label{fig:left}
  \end{subfigure}%
  \hfill
  \begin{subfigure}{0.39\linewidth}
    % Length
    \setlength{\figwidth}{\linewidth}
    % Figure
    \centering
    \includegraphics[width=\figwidth,height=\figheight,keepaspectratio]{example-image-b}
    \caption{\the\figdim, \the\figheight, right}%
    \label{fig:right}
  \end{subfigure}%
  \caption{Test}
  \label{fig}
\end{figure}

\end{document}

输出

有关的

• 副标题：两个垂直尺寸不同的图像的垂直对齐
• 子字幕垂直对齐

---

更新

遵循@Werner 的方法：

\documentclass{article}

\usepackage{graphicx}
\usepackage{subcaption}

\newlength{\figwidth}
\newlength{\figheight}
\newlength{\figdim}

\begin{document}

\begin{figure}[htbp]

  % Length
  \setlength{\figwidth}{0.59\linewidth}
  \setlength{\figheight}{5cm}
  \settoheight\figdim{\includegraphics[width=\figwidth,height=\figheight,keepaspectratio]{example-image-a}}
  \setlength{\figheight}{\figdim}

  \begin{subfigure}{0.59\linewidth}
    % Figure
    \centering
    \includegraphics[width=\figwidth,height=\figheight,keepaspectratio]{example-image-a}
    \caption{\the\figheight, left}%
    \label{fig2:left}
  \end{subfigure}%
  \hfill
  \begin{subfigure}{0.39\linewidth}
    % Figure
    \centering
    \includegraphics[width=\figwidth,height=\figheight,keepaspectratio]{example-image-b}
    \caption{\the\figheight, right}%
    \label{fig2:right}
  \end{subfigure}%
  \caption{Test}
  \label{fig2}
\end{figure}

\end{document}

不幸的是，必须将宽度因子（x*\linewidth）改变两次。

---

更新 2

\documentclass{article}

\usepackage{graphicx}
\usepackage{subcaption}

\newlength{\figwidth}
\newlength{\figheight}
\newlength{\figdim}

\begin{document}

\begin{figure}[htbp]
  \begin{subfigure}{0.59\linewidth}
    % Length
    \setlength{\figwidth}{0.7\linewidth}
    \setlength{\figheight}{5cm}
    \settoheight\figdim{\includegraphics[width=\figwidth,height=\figheight,keepaspectratio]{example-image-16x9}}
    \global\setlength{\figwidth}{\figwidth}
    \global\setlength{\figheight}{\figdim}
    % Figure
    \centering
    \includegraphics[width=\figwidth,height=\figheight,keepaspectratio]{example-image-16x9}
    \caption{\the\figdim, \the\figheight, left}%
    \label{fig3:left}
  \end{subfigure}%
  \hfill
  \begin{subfigure}{0.39\linewidth}
    % Length
    \setlength{\figwidth}{\linewidth}
    % Figure
    \centering
    \includegraphics[width=\figwidth,height=\figheight,keepaspectratio]{example-image-16x10}
    \caption{\the\figdim, \the\figheight, right}%
    \label{fig3:right}
  \end{subfigure}%
  \caption{Test}
  \label{fig3}
\end{figure}

\end{document}

Answer 1

这是范围限定的结果 - 如果在组内进行长度更改，则一旦退出该组，更改就会被恢复。下面是一个显示此情况的最小示例：

\documentclass{article}

\newlength{\mylength}

\begin{document}

\setlength{\mylength}{100pt}
\the\mylength

\begingroup
\setlength{\mylength}{200pt}
\the\mylength
\endgroup

\the\mylength

\end{document}

由于您正在环境内捕获图像尺寸subfigure，因此一旦退出该环境，这些长度就会丢失。

解决方案是收集环境内figure和subfigure环境外的信息：

\documentclass{article}

\usepackage{graphicx}
\usepackage{subcaption}

\newlength{\figwidth}
\newlength{\figheight}
\newlength{\figdim}

\begin{document}

\begin{figure}[htbp]
  % Length
  \setlength{\figwidth}{\linewidth}
  \setlength{\figheight}{5cm}
  \settoheight\figdim{\includegraphics[width=\figwidth,height=\figheight,keepaspectratio]{example-image-a}}
  \setlength{\figheight}{\figdim}
  \begin{subfigure}{0.59\linewidth}
    % Figure
    \centering
    \includegraphics[width=\figwidth,height=\figheight,keepaspectratio]{example-image-a}
    \caption{\the\figdim, \the\figheight, left}%
  \end{subfigure}%
  \hfill
  \begin{subfigure}{0.39\linewidth}
    % Length
    \setlength{\figwidth}{\linewidth}
    % Figure
    \centering
    \includegraphics[width=\figwidth,height=\figheight,keepaspectratio]{example-image-b}
    \caption{\the\figdim, \the\figheight, right}%
  \end{subfigure}%
  \caption{Test}
\end{figure}

\end{document}