Regarding the leftbar environment

Question

Does anyone know how to control the width and color of the left bar in the leftbar environment?

Answer 1

Ignore the optional argument:

\documentclass{article}
\usepackage{xcolor}
\usepackage{framed}

\renewenvironment{leftbar}[1][\hsize]
{%
    \def\FrameCommand
    {%
        {\color{red}\vrule width 3pt}%
        \hspace{0pt}%must no space.
        \fboxsep=\FrameSep\colorbox{yellow}%
    }%
    \MakeFramed{\hsize#1\advance\hsize-\width\FrameRestore}%
}
{\endMakeFramed}

\def\fact{It is practically a big lie that LaTeX makes you focus on the content without bothering about the layout.}
\begin{document}
\fact
\leftbar
\fact
\endleftbar
\fact
\end{document}

Specify the optional argument:

You can specify the optional argument as the following example:

\documentclass{article}
\usepackage{xcolor}
\usepackage{framed}

\renewenvironment{leftbar}[1][\hsize]
{%
    \def\FrameCommand
    {%
        {\color{red}\vrule width 3pt}%
        \hspace{0pt}%must no space.
        \fboxsep=\FrameSep\colorbox{yellow}%
    }%
    \MakeFramed{\hsize#1\advance\hsize-\width\FrameRestore}%
}
{\endMakeFramed}

\def\fact{It is practically a big lie that LaTeX makes you focus on the content without bothering about the layout.}
\begin{document}
\fact
\leftbar[0.75\linewidth]
\fact
\endleftbar
\fact
\end{document}

Answer 2

The width and color (i.e. the non-use of color) seems to be hard-coded into this environment:

\leftbar:
\long macro:->\def \FrameCommand {\vrule width 3pt \hspace {10pt}}\MakeFramed {\advance \hsize -\width \FrameRestore }


\endleftbar:
\long macro:->\endMakeFramed 

Simply define your own version which the appropriate color and width. The best thing is to add length register which values can be changed afterwards:

\documentclass{article}

\usepackage{framed}
\usepackage{xcolor}
\usepackage{lipsum}% dummy text


\newlength{\leftbarwidth}
\setlength{\leftbarwidth}{3pt}
\newlength{\leftbarsep}
\setlength{\leftbarsep}{10pt}

\newcommand*{\leftbarcolorcmd}{\color{leftbarcolor}}% as a command to be more flexible
\colorlet{leftbarcolor}{black}

\renewenvironment{leftbar}{%
    \def\FrameCommand{{\leftbarcolorcmd{\vrule width \leftbarwidth\relax\hspace {\leftbarsep}}}}%
    \MakeFramed {\advance \hsize -\width \FrameRestore }%
}{%
    \endMakeFramed
}


\begin{document}

\begin{leftbar}
\lipsum
\end{leftbar}


\setlength{\leftbarwidth}{5pt}
\setlength{\leftbarsep}{8pt}
\colorlet{leftbarcolor}{blue}

\begin{leftbar}
\lipsum
\end{leftbar}

\end{document}