Add a rule underneath “Figure 1”

Question

I want to add a line beneath the figure caption such as

Figure 1

---

Figure caption text here....

I managed to include a newline, change the color and look of the caption via caption package:

\usepackage[font=small,
            format=plain,
            labelformat=simple, 
            labelsep=newline,
            singlelinecheck=false,
            labelfont=bf,
            up
            ]{caption}
\captionsetup{labelfont={color=mybluecolor,bf}}

but cannot put a line (horizontal rule) as in the linked example. How can I do this?

Answer 1

The caption package allows you to define your own caption format with \DeclareCaptionFormat.

\DeclareCaptionFormat{<name>}{<code using #1, #2 and #3>}

where #1 refers to the label, #2 to the label separator and #3 to the caption text. This is described in section 4 Own Enhancements of the caption manual. Here is an example using tabu to typeset the caption which should give you a general idea:

\documentclass{article}
\usepackage{caption,xcolor,tabu}
\colorlet{captionlabel}{blue!100!black!85}

\DeclareCaptionFormat{custom}{%
 \begin{tabu} to \linewidth {@{}X@{}}
   \strut #1 \\\hline
   \strut #3
 \end{tabu}
}
\captionsetup{
  font=small,
  format=custom,
  singlelinecheck=false,
  labelfont={bf,color=captionlabel}
}
\usepackage{lipsum}
\begin{document}

\lipsum[1]

\begin{figure}[ht]
 \centering
 \rule{5cm}{3cm}
 \caption{\protect\lipsum*[4]}
\end{figure}

\lipsum[2]

\end{document}

Answer 2

A way with minimal intervention: just declare a new separator.

\documentclass{article}

\usepackage[demo]{graphicx}
\usepackage{xcolor}
\definecolor{mybluecolor}{rgb}{.204,.486,.741}
\usepackage{lipsum}

\usepackage{caption}

%%% Define a new caption separator
\DeclareCaptionLabelSeparator*{newlinerule}{\par\kern2pt\hrule\kern1pt}

\captionsetup{
  font=small,
  format=plain,
  labelformat=simple,
  labelsep=newlinerule,
  singlelinecheck=false,
  labelfont={color=mybluecolor,bf},
}

\begin{document}

\lipsum[1]

\begin{figure}[!hp]
\centering
\includegraphics[width=.8\textwidth]{x}
\caption{\protect\lipsum*[2]}
\end{figure}

\lipsum[3]

\end{document}