Tikz Dim Code

dim.tex

% Given the name of two tikz nodes, this dims the lines starting at node 1, ending at node 2
\newcommand{\dimtext}[2]%
{
  { \transparent{0.7}
  \begin{tikzpicture}[overlay, remember picture]
    \fill[white] ( #1 -| current page.north west) -- ++(0,1em) -- ++(\paperwidth,0) -- (#2 -| current page.north east)
     -- ++(0,-.5em) -- ++(-\paperwidth,0) -- cycle;
  \end{tikzpicture}
  }
}[

\begin{document}
  %The first function will be "dimmed", looking transparent
  \begin{lstlisting}[escapeinside={(*}{*)}]
  void foo(int x)(*\tikzmark{begin_dim}*)
  {
    // Do something
  }(*\tikzmark{end_dim}*)
  
  int main(int,char**)
  {
    std::cout << "Hello world!" << std::endl;
  }
  \end{lstlisting}
  
  \dimtext{begin_dim}{end_dim}
  
\end{document}