%% Copyright (C) 2017 Achim D. Brucker, https://www.brucker.ch
%%
%% License:
%%   This program can be redistributed and/or modified under the terms
%%   of the LaTeX Project Public License Distributed from CTAN
%%   archives in directory macros/latex/base/lppl.txt; either
%%   version 1 of the License, or any later version.
%%   OR
%%   The 2-clause BSD-style license.
%%
\NeedsTeXFormat{LaTeX2e}[1994/06/01]
\ProvidesPackage{beamerboxeslhframed}
     [2017/05/01 v0.0  Framed boxes for Beamer.]

\usepackage{ifthen}
\newboolean{lh@framed@rounded}
\setboolean{lh@framed@rounded}{false}
%\setboolean{lh@framed@rounded}{true}

\newlength{\lh@frame@linewidth}
\setlength{\lh@frame@linewidth}{2pt}
\newcommand{\setlhframedlinewidth}[1]{\setlength{\lh@frame@linewidth}{#1}}

\newlength{\lh@frame@margin}
\setlength{\lh@frame@margin}{3pt}
\newcommand{\setlhframedmargin}[1]{\setlength{\lh@frame@margin}{#1}}

\newlength{\lh@bmb@width}



\newcommand\beamerboxesframed[2][]{%
  \global\let\beamer@firstlineitemizeunskip=\relax%
  \vbox\bgroup%
  \setkeys{beamerboxes}{upper=block title,lower=block body,width=\textwidth}%
  \setkeys{beamerboxes}{#1}%
  {%
    \usebeamercolor{\bmb@lower}%
    \globalcolorstrue%
    \colorlet{lower.bg}{bg}%
  }%
  {%
    \usebeamercolor{\bmb@upper}%
    \globalcolorstrue%
    \colorlet{upper.bg}{bg}%
  }%
  %
  % Typeset head
  %
\lh@bmb@width=\bmb@width%
\advance\lh@bmb@width-\lh@frame@margin%
\advance\lh@bmb@width-\lh@frame@margin%
  \vskip4bp
  \setbox\bmb@box=\hbox{#2}%
  \ifdim\wd\bmb@box=0pt%
  \relax%
  \else
    \setbox\bmb@box=\hbox{%
    \hspace{\lh@frame@margin}\begin{minipage}[b]{\lh@bmb@width}%
      \usebeamercolor[fg]{\bmb@upper}%
        {\vskip\lh@frame@margin}#2{\vspace{\lh@frame@margin}}%
    \end{minipage}}%
  \fi%
  \ifdim\wd\bmb@box=0pt%
    \setbox\bmb@box=\hbox{}%
    \ht\bmb@box=0pt%
    \bmb@prevheight=-4.5pt%
  \else%
    \wd\bmb@box=\bmb@width%
    \bmb@temp=\dp\bmb@box%
    \ifdim\bmb@temp<1.5pt%
      \bmb@temp=1.5pt%
    \fi%
    \setbox\bmb@box=\hbox{\raise\bmb@temp\hbox{\box\bmb@box}}%
    \dp\bmb@box=0pt%
    \bmb@prevheight=\ht\bmb@box%
  \fi%
  \bmb@temp=\bmb@width%
  \bmb@dima=\bmb@temp\advance\bmb@dima by2.2bp%
  \bmb@dimb=\bmb@temp\advance\bmb@dimb by4bp%
  \hbox{%
    \begin{pgfpicture}{0bp}{+-\ht\bmb@box}{0bp}{+-\ht\bmb@box}
      \pgfsetlinewidth{\lh@frame@linewidth}
      \ifdim\wd\bmb@box=0pt%
        \color{lower.bg}%
      \else%
        \color{upper.bg}%
      \fi%
      \pgfpathqmoveto{-4bp}{-1bp}
%% <corner>
\ifthenelse{\boolean{lh@framed@rounded}}{%
      \pgfpathqcurveto{-4bp}{1.2bp}{-2.2bp}{3bp}{0bp}{3bp}
}{%
      \pgfpathlineto{\pgfpoint{-4bp}{3bp}}
}
%% </corner>
      \pgfpathlineto{\pgfpoint{\bmb@temp}{3bp}}
%% <corner>
\ifthenelse{\boolean{lh@framed@rounded}}{%
      \pgfpathcurveto%
      {\pgfpoint{\bmb@dima}{3bp}}%
      {\pgfpoint{\bmb@dimb}{1.2bp}}%
      {\pgfpoint{\bmb@dimb}{-1bp}}%
}{%
      \pgfpathlineto{\pgfpoint{\bmb@dimb}{3bp}}
}
%% </corner>
      \bmb@dima=-\ht\bmb@box%
      \advance\bmb@dima by-2pt%
      \pgfpathlineto{\pgfpoint{\bmb@dimb}{\bmb@dima}}
      \pgfpathlineto{\pgfpoint{-4bp}{\bmb@dima}}
      \pgfpathclose
      \pgfsetstrokecolor{black}\pgfusepath{stroke, fill}
    \end{pgfpicture}%
    \copy\bmb@box%
  }%
  \nointerlineskip%
  \ifdim\wd\bmb@box=0pt
  \else
    \vskip2.4pt%
  \fi%
  \nointerlineskip%
  \setbox\bmb@colorbox=\hbox{{\pgfpicturetrue\pgfsetcolor{lower.bg}}}%
  \setbox\bmb@box=\hbox\bgroup\hspace{\lh@frame@margin}\begin{minipage}[b]{\lh@bmb@width}%
    \usebeamercolor[fg]{\bmb@lower}%
    \colorlet{beamerstructure}{upper.bg}%
    {\smallskip\vskip\lh@frame@margin}%
    \colorlet{structure}{upper.bg}%
    %\color{.}%
}


\def\endbeamerboxesframed{%
  {\vskip\lh@frame@margin}%
  \end{minipage}\egroup%
  \wd\bmb@box=\bmb@width%
  \bmb@temp=\dp\bmb@box%
  \advance\bmb@temp by\lh@frame@margin%
  \setbox\bmb@box=\hbox{\raise\bmb@temp\hbox{\box\bmb@box}}%
  \dp\bmb@box=0pt%
  \bmb@temp=\wd\bmb@box%
  \bmb@dima=\bmb@temp\advance\bmb@dima by2.2bp%
  \bmb@dimb=\bmb@temp\advance\bmb@dimb by4bp%
  \hbox{%
    \begin{pgfpicture}{0bp}{0bp}{0bp}{0bp}
      \pgfsetlinewidth{\lh@frame@linewidth}
      \unhbox\bmb@colorbox%
      \pgfpathmoveto{\pgfpoint{-4bp}{\ht\bmb@box}}
      \pgfpathlineto{\pgfpoint{-4bp}{1bp}}
%% <corner>
\ifthenelse{\boolean{lh@framed@rounded}}{%
     \pgfpathqcurveto{-4bp}{-1.2bp}{-2.2bp}{-3bp}{0bp}{-3bp}
}{%
      \pgfpathlineto{\pgfpoint{-4bp}{-3bp}}
}
%% </corner>
      \pgfpathlineto{\pgfpoint{\the\bmb@temp}{-3bp}}
%% <corner>
\ifthenelse{\boolean{lh@framed@rounded}}{%
      \pgfpathcurveto%
      {\pgfpoint{\the\bmb@dima}{-3bp}}%
      {\pgfpoint{\the\bmb@dimb}{-1.2bp}}%
      {\pgfpoint{\the\bmb@dimb}{1bp}}%
}{%
      \pgfpathlineto{\pgfpoint{\the\bmb@dimb}{-3bp}}
}
%% </corner>
      {
      \bmb@dima=\ht\bmb@box%
      \pgfpathlineto{\pgfpoint{\bmb@dimb}{\bmb@dima}}
      \pgfsetstrokecolor{black}\pgfusepath{stroke, fill}
      }
    \end{pgfpicture}%
    \box\bmb@box%
  }%
  \vskip2bp%
  \egroup% of \vbox\bgroup
}