Two large figures side by side

Question

Question

I want to place two TikZ pictures side by side:

Note:

• They are vertically centered.
• One is wider than half the page.
• The three gaps are equal (as if by using \hfil <a> \hfil <b> \hfil).
• The captions are vertically aligned.

Long captions should also be handled correctly (i.e. they should wrap, just like they normally do).

The solution should avoid trial-and-error lengths such as \begin{minipage}{5.95cm}, \begin{minipage}{0.3\textwidth} and \qquad.

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What I've tried

I've looked at about two dozen questions here but none of the answers were satisfactory. This section is an attempt to summarize them and address their flaws.

Assume the following preamble:

\documentclass{article}

\usepackage[showframe]{geometry}
\usepackage{tikz}
\usepackage{caption}
\usepackage{subfig}
\usepackage{floatrow}
\usepackage{tabularx}

\newcommand\rectangle[2]{%
    \begin{tikzpicture}[baseline=(current bounding box.center)]
        \draw(0,0) rectangle(#1, #2);
    \end{tikzpicture}%
}

minipage

\vspace{0.5cm}
\noindent
\begin{minipage}{5.95cm} % (1)
    \centering
    \rectangle{4}{8}
    \captionsetup{type=figure}
    \caption{A tall boi.}
\end{minipage}
\begin{minipage}{8cm}
    \rectangle{8}{4}
    \captionsetup{type=figure}
    \caption{A wide boi.} % (2)
\end{minipage}
\vspace{0.5cm} % (3)

Problems

1. The minipage widths are determined through trial and error.
2. The captions aren't vertically aligned.
3. I don't know how much vspace to use. If I don't use any, there is no vertical space between the figures and the paragraphs.

---

subfloat

\begin{figure}[H]
    \centering
    \subfloat[\centering A tall boi.]{% (1)
        \rectangle{4}{8}
    }%
    \qquad% (2)
    \subfloat[\centering A wide boi.]{% (3)
        \rectangle{8}{4}
    }
\end{figure}

Problems

1. The captions are a different style and have different numbering.
2. The spacing between the figures is determined through trial and error.
3. The captions aren't vertically aligned.

---

floatrow

\begin{figure}[H]
    \centering
    \begin{floatrow}
        \ffigbox[\FBwidth]{\caption{A tall boi.}}{%
            \rectangle{4}{8}
        }% (1)
        \ffigbox[\FBwidth]{\caption{A wide boi.}}{%
            \rectangle{8}{4} % (2)
        }%
    \end{floatrow}
\end{figure}

Problems

1. The spacing is wrong.
2. The figures aren't vertically centered.

---

tabularx

\vspace{0.5cm} % (1)
\noindent
\begin{tabularx}{\textwidth}{XX} % (2)
    \rectangle{4}{8} &
    \rectangle{8}{4} \\
    \captionsetup{type=figure}
    \caption{A tall boi.} &
    \captionsetup{type=figure}
    \caption{A wide boi.}
\end{tabularx}

Problems

1. \vspace again.
2. Both columns are equally wide (wide enough to fit the second figure).

This is the best one so far

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Minimal working example

\documentclass{article}

\usepackage[showframe]{geometry}
\usepackage{tikz}
\usepackage{lipsum}

\newcommand\rectangle[2]{%
    \begin{tikzpicture}[baseline=(current bounding box.center)]
        \draw(0,0) rectangle(#1, #2);
    \end{tikzpicture}%
}

\begin{document}

\lipsum[1][1-3]

\noindent\hfil
\rectangle{4}{8}
\hfil
\rectangle{8}{4}
\hfil

\lipsum[2][1-3]

\end{document}

Answer 1

This uses a combination of saveboxes and \parboxes. The captions are placed in \parboxes to control the width (minipages will do just as well). The \nulls prevent \abovecaptionskip from geing ignored.

\documentclass{article}

\usepackage[showframe]{geometry}
\usepackage{tikz}
\usepackage{lipsum}
\usepackage{caption}

\newcommand\rectangle[2]{%
    \begin{tikzpicture}[baseline=(current bounding box.center)]
        \draw(0,0) rectangle(#1, #2);
    \end{tikzpicture}%
}

\begin{document}

\lipsum[1][1-3]

\begin{figure}[ht]
\sbox0{\rectangle{4}{8}}% measure width
\sbox1{\rectangle{8}{4}}%
\centering
\usebox0\hfil\usebox1\par
\parbox[t]{\wd0}{\null
    \caption{A tall boi.}}\hfil
\parbox[t]{\wd1}{\null
    \caption{A wide boi.}}
\end{figure}

\lipsum[2][1-3]

\end{document}

Answer 2

As starting point:

• use tabularray package
• calculate table column separator(s). In your case by

(\linewidth-<width of first image>-<width of second image>)/6

where 6 is number of column separators in table.

In the cases, when width of images is know in advance, than MWE in your particular case can be:

\documentclass{article}

\usepackage[showframe]{geometry}
\usepackage{tikz}
\usepackage{lipsum}

\usepackage{tabularray}
\UseTblrLibrary{counter}
\newcommand\rectangle[2]{%
    \begin{tikzpicture}[baseline=(current bounding box.center)]
        \draw(0,0) rectangle(#1, #2);
    \end{tikzpicture}%
}

\begin{document}
\lipsum[1][1-3]
    \begin{figure}[ht]
    \centering
\begin{tblr}{colsep = {(\linewidth-8cm-4cm)/6},
             colspec = {Q[m, wd=4cm] Q[m, wd=8cm]},
             row{2}  = {h},
             }
\rectangle{4}{8}
    &
\rectangle{8}{4}    \\
\caption{figure 1}
    &   \caption{figure 2}
\end{tblr}
    \end{figure}
   
\lipsum[2][1-3] 
\end{document}

Edit:
However, when the width of images is unknown in advance, you need to measure their width similarly as @John Kormylo do in his answer and inset those width in width of columns and use in calculation of colsep as is indicated at beginning of answer:

\usepackage[showframe]{geometry}
\usepackage{tikz}
\usepackage[skip=1ex]{caption}
\usepackage{lipsum}

\usepackage{tabularray}
\UseTblrLibrary{counter}
\newcommand\rectangle[2]{%
    \begin{tikzpicture}[baseline=(current bounding box.center)]
        \draw(0,0) rectangle(#1, #2);
    \end{tikzpicture}%
}

\begin{document}
\lipsum[1][1-3]
    \begin{figure}[ht]
    \centering
\sbox0{\rectangle{4}{8}}% measure of the first image width
\sbox1{\rectangle{8}{4}}% measure of the second image width
\begin{tblr}{colsep = {(\linewidth-\wd0-\wd01)/6},
             colspec = {Q[m, wd=\wd0] Q[m, wd=\wd1]},
             row{2}  = {h},
             rowsep  = 0pt
             }
\rectangle{4}{8}
    &
\rectangle{8}{4}    \\
\caption{figure 1}
    &   \caption{figure 2}
\end{tblr}
    \end{figure}
   
\lipsum[2][1-3] 
\end{document}

Result is the same as before.

Answer 3

This answer extends John's answer:

Before	After

\documentclass{article}

\usepackage[showframe]{geometry}
\usepackage{tikz}
\usepackage{lipsum}
\usepackage{caption}
\usepackage{calc}

\newcommand\rectangle[2]{%
    \begin{tikzpicture}[baseline=(current bounding box.center)]
        \draw(0,0) rectangle(#1, #2);
    \end{tikzpicture}%
}

\begin{document}

\lipsum[1][1-3]

\begin{figure}[ht]
\sbox0{\rectangle{3}{6}}%
\sbox1{\rectangle{6}{3}}%
\centering
\usebox0\hfil\usebox1\par
\parbox[t]{\wd0+(\textwidth-\wd0-\wd1)/3-6pt}{\null% (2)
    \caption{\lipsum[1][4-6]}}%
\hspace{6pt}% (1)
\parbox[t]{\wd1+(\textwidth-\wd0-\wd1)/3-6pt}{\null% (2)
    \caption{\lipsum[1][7-9]}}%
\end{figure}

\lipsum[2][1-3]

\end{document}

1. The caption \parboxes have a 6pt gap between them. This is the default gap between columns in the tabular environment.
2. The width of each \parbox is the width of its corresponding figure (determined with \wd) plus the width of the space between the figures ((\textwidth-\wd0-\wd1)/3) minus the gap between the \parboxes (6pt). This ensures that they are centered under their respective figures.

The trailing comments are required to prevent line breaks from getting expanded to spaces.