Centering figure caption does not work

Question

I have a few narrow figures for which I want to center the caption. I have to use a LaTeX template from Springer (svmult.cls). This makes captions left-aligned by default. I took a look at this question which suggest to add the captions package and then locally use

\captionsetup{justification=centering}

But this has no effect in this case. The relevant part from the class file looks like this:

\usepackage{subfig}
% redefininition of the captions for "figure" and "table" environments
%
\@ifundefined{floatlegendstyle}{\def\floatlegendstyle{\bfseries}}{}
\def\floatcounterend{\enspace}
\def\capstrut{\vrule\@width\z@\@height\topskip}
\@ifundefined{captionstyle}{\def\captionstyle{\normalfont\small}}{}
\@ifundefined{instindent}{\newdimen\instindent}{}

\long\def\@caption#1[#2]#3{\par\addcontentsline{\csname
  ext@#1\endcsname}{#1}{\protect\numberline{\csname
  the#1\endcsname}{\ignorespaces #2}}\begingroup
    \@parboxrestore\if@minipage\@setminipage\fi
    \@makecaption{\csname fnum@#1\endcsname}{\ignorespaces #3}\par
  \endgroup}

\def\twocaptionwidth#1#2{\def\first@capwidth{#1}\def\second@capwidth{#2}}
% Default: .46\textwidth
\twocaptionwidth{.46\textwidth}{.46\textwidth}

\def\leftcaption{\refstepcounter\@captype\@dblarg%
            {\@leftcaption\@captype}}

\def\rightcaption{\refstepcounter\@captype\@dblarg%
            {\@rightcaption\@captype}}

\long\def\@leftcaption#1[#2]#3{\addcontentsline{\csname
  ext@#1\endcsname}{#1}{\protect\numberline{\csname
  the#1\endcsname}{\ignorespaces #2}}\begingroup
    \@parboxrestore
    \vskip\figcapgap
    \@maketwocaptions{\csname fnum@#1\endcsname}{\ignorespaces #3}%
    {\first@capwidth}\ignorespaces\hspace{.073\textwidth}\hfill%
  \endgroup}

\long\def\@rightcaption#1[#2]#3{\addcontentsline{\csname
  ext@#1\endcsname}{#1}{\protect\numberline{\csname
  the#1\endcsname}{\ignorespaces #2}}\begingroup
    \@parboxrestore
    \@maketwocaptions{\csname fnum@#1\endcsname}{\ignorespaces #3}%
    {\second@capwidth}\par
  \endgroup}

\long\def\@maketwocaptions#1#2#3{%
   \parbox[t]{#3}{{\floatlegendstyle #1\floatcounterend}#2}}

\def\fig@pos{l}
\newcommand{\leftfigure}[2][\fig@pos]{\makebox[.4635\textwidth][#1]{#2}}
\let\rightfigure\leftfigure

\newdimen\figgap\figgap=0.5cm  % hgap between figure and sidecaption
%
\long\def\@makesidecaption#1#2{\@tempdimb=3.6cm
   \setbox0=\vbox{\hsize=\@tempdimb
                  \captionstyle{\floatlegendstyle
                                         #1\floatcounterend}#2}%
   \ifdim\instindent<\z@
      \ifdim\ht0>-\instindent
         \advance\instindent by\ht0
         \typeout{^^JClass-Warning: Legend of \string\sidecaption\space for
                     \@captype\space\csname the\@captype\endcsname
                  ^^Jis \the\instindent\space taller than the corresponding float -
                  ^^Jyou'd better switch the environment. }%
         \instindent\z@
      \fi
   \else
      \ifdim\ht0<\instindent
         \advance\instindent by-\ht0
         \advance\instindent by-\dp0\relax
         \advance\instindent by\topskip
         \advance\instindent by-11\p@
      \else
         \advance\instindent by-\ht0
         \instindent=-\instindent
         \typeout{^^JClass-Warning: Legend of \string\sidecaption\space for
                     \@captype\space\csname the\@captype\endcsname
                  ^^Jis \the\instindent\space taller than the corresponding float -
                  ^^Jyou'd better switch the environment. }%
         \instindent\z@
      \fi
   \fi
   \parbox[b]{\@tempdimb}{\captionstyle{\floatlegendstyle
                                        #1\floatcounterend}#2%
                          \ifdim\instindent>\z@ \\
                               \vrule\@width\z@\@height\instindent
                                     \@depth\z@
                          \fi}}
\def\sidecaption{\@ifnextchar[\sidec@ption{\sidec@ption[b]}}
%
\newbox\bildb@x
%
\def\sidec@ption[#1]#2\caption{%
\setbox\bildb@x=\hbox{\ignorespaces#2\unskip}%
\if@twocolumn
 \ifdim\hsize<\textwidth\else
   \ifdim\wd\bildb@x<\columnwidth
      \typeout{Double column float fits into single column -
            ^^Jyou'd better switch the environment. }%
   \fi
 \fi
\fi
  \instindent=\ht\bildb@x
  \advance\instindent by\dp\bildb@x
\if t#1
\else
  \instindent=-\instindent
\fi
\@tempdimb=\hsize
\advance\@tempdimb by-\figgap
\advance\@tempdimb by-\wd\bildb@x
\ifdim\@tempdimb<3.6cm
   \ClassWarning{SVMult}{\string\sidecaption: No sufficient room for the legend;
             ^^Jusing normal \string\caption}%
   \unhbox\bildb@x
   \let\@capcommand=\@caption
\else
%  \ifdim\@tempdimb<4.5cm
%     \ClassWarning{SVMono}{\string\sidecaption: Room for the legend very narrow;
%              ^^Jusing \string\raggedright}%
      \toks@\expandafter{\captionstyle\sloppy
                         \rightskip=\z@\@plus6mm\relax}%
      \def\captionstyle{\the\toks@}%
%  \fi
   \let\@capcommand=\@sidecaption
%  \leavevmode
%  \unhbox\bildb@x
%  \hfill
\fi
\refstepcounter\@captype
\@dblarg{\@capcommand\@captype}}
\long\def\@sidecaption#1[#2]#3{\addcontentsline{\csname
  ext@#1\endcsname}{#1}{\protect\numberline{\csname
  the#1\endcsname}{\ignorespaces #2}}\begingroup
    \@parboxrestore
    \@makesidecaption{\csname fnum@#1\endcsname}{\ignorespaces #3}%
    \hfill
    \unhbox\bildb@x
    \par
  \endgroup}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

As far as I understand, it merely defines extra captions for figures composed of two horizontal sub figures?

Any idea why the captionsetup doesn't work in this case, and if there is a work around (perhaps using something in subfig as that package is already included).

---

EDIT: Here is a minimal example:

\documentclass[graybox]{svmult}
\begin{document}
\begin{figure}
\centering
My graphics
\captionsetup{justification=centering}
\caption{My caption}
\end{figure}
\end{document}

Where svmult.cls is available from Springer.

Answer 1

Use a minipage.

\documentclass[graybox]{svmult}
\begin{document}
\begin{figure}
\centering
\begin{minipage}{.33\textwidth}
\centering

This text is supposed to substitute the image
in this figure environment

\caption{My caption}
\end{minipage}
\end{figure}
\end{document}

Answer 2

Adding \usepackage{caption} results in a center-aligned caption

\documentclass[graybox]{svmult}
\usepackage{caption}

\begin{document}
\begin{figure}
\centering
My graphics
\captionsetup{justification=centering}
\caption{My caption dfhu orifv My caption dfhu orifv My caption dfhu orifv My caption dfhu orifv My caption dfhu orifv My caption dfhu orifv My caption dfhu orifv My caption dfhu orifv My caption dfhu orifv My caption dfhu orifv My caption dfhu orifv My caption dfhu orifv My caption dfhu orifv My caption dfhu orifv My caption dfhu orifv My caption dfhu orifv My caption dfhu orifv My caption dfhu orifv }
\end{figure}
\end{document}