Empty captions with KOMA-script, maybe together with hyperref

Question

I like captions to normally have a colon, but not when the caption is empty. This is something that the package caption does automatically, so

\documentclass{scrartcl}

\usepackage{caption}
\usepackage{hyperref}

\begin{document}
\begin{figure}
  \caption{Test}
  \caption{}
\end{figure}
\end{document}

yields

which is what I want. But I want to use KOMA captions without the caption package, and then I get "Figure 1: Test / Figure 2:" with the extra colon at the end. How can I patch it to make it as I want?

I need a solution that works together with hyperref. An answer to this earlier question where hyperref isn't involved doesn't work with it, so it may complicate things.

Answer 1

Well I think it is really the better way to typeset and measure the caption instead of looking at the tokens:

 \documentclass{scrartcl}

\usepackage{hyperref}

\usepackage{xpatch}
\makeatletter
\patchcmd\@@makecaption{\begingroup}
{%
 \settowidth{\@tempdima}{#3}%
 \ifdim\@tempdima=0pt
  \def\captionformat{}%
 \fi
  \begingroup
}{}{\fail}

\begin{document}
\begin{figure}
  \caption{Test}
  \caption{}
  \caption{ }
  \caption{new}
\end{figure}
\end{document}

Without hyperref this will also remove the colons for the caption with a space in it, but with hyperref this space counts.