LaTex listing and caption - How to exactly align frame

Question

I want to use a nicely formatted caption for my listings, as proposed in LaTeX source code listing like in professional books. Additionally the content should be framed.

\documentclass{report}

\usepackage{color}
\usepackage{xcolor}
\usepackage{listings}

\usepackage{caption}
\DeclareCaptionFont{white}{\color{white}}
\DeclareCaptionFormat{listing}{\colorbox{gray}{\parbox{\textwidth}{#1#2#3}}}
\captionsetup[lstlisting]{format=listing,labelfont=white,textfont=white}

\lstdefinestyle{framed}
{
     frame=lrb,         
     belowcaptionskip=-1pt,
     xleftmargin=8pt,
     framexleftmargin=8pt,
     framexrightmargin=5pt,
     framextopmargin=5pt,
     framexbottommargin=5pt,
     framesep=0pt,
     rulesep=0pt,
 }

\begin{document}

\begin{lstlisting}[style=framed,label=some-code,caption=Some Code]
public void here() {
    goes().the().code()
}
\end{lstlisting}

\end{document}

Results in:

As you can clearly see, the frame is misaligned by about 1px to the left. Zooming in leads me to the conclusion that this is du to the border-settings of the caption itself. However I cannot find any information how to configure the border with \captionsetup.

Any ideas how to resolve this are very much appreciated.

Answer 1

Somebody else gave me a great hint, one just has to move the caption box slightly to the left manually:

DeclareCaptionFont{white}{\color{white}} 
\DeclareCaptionFormat{listing}{% 
  \hspace*{-0.4pt}\colorbox{gray}{\parbox{\dimexpr\textwidth-2\fboxsep+.8pt\relax}{#1#2#3}}} 
\captionsetup[lstlisting]{format=listing,labelfont=white,textfont=white}