patch instead of completely redefine beamer@frameslide

MRTbeam/beamerouterthemeMRTbeam.sty

@@ -1,5 +1,7 @@
 \mode<presentation>
 
+\RequirePackage{etoolbox}
+
 \setbeamertemplate{background}{%>>=
   \begin{tikzpicture}
     \useasboundingbox (0,0) rectangle(\paperwidth,\paperheight);
@@ -62,117 +64,21 @@
 
 %% Invoke `noframetitle` if no frametitle was given >>=
 %% Code based on https://tex.stackexchange.com/a/389258/117050
-\renewenvironment{beamer@frameslide}{%
-  \ifbeamer@autobreak\else%
-    \ifx\beamer@againname\@empty%
-      {\let\@elt\beamer@restorecounter\beamer@overlaycounterresets}%
-    \else%
-      {\let\@elt\beamer@labelrestorecounter\beamer@overlaycounterresets}%
-    \fi%
-  \fi%
-  \global\c@beamerpauses=1\relax%
-  \expandafter\ifblank\expandafter{\beamer@framestartpage}{%
-    \stepcounter{subsectionslide}%
-    \xdef\beamer@framestartpage{\the\c@page}% only first time
-  }{\clearpage\beamer@notesactions}% cleanup from previous slide
-  \hypersetup{pdfpagetransition=R}%
-  \hypersetup{pdfpageduration=}%
-  \@ifundefined{thispdfpagelabel}{}{%
-  \thispdfpagelabel{\insertframenumber}}%
-  \xdef\beamer@frameendpage{\the\c@page}% every time
-  \beamer@setuplinks%
-  \beamer@displaybreak%
-  \global\setbox\beamer@zoombox=\box\voidb@x%
-  \def\beamer@zoomer{}%
-  \beamer@slidehaszoomfalse%
-  \gdef\insertframetitle{}%
-  \gdef\insertframesubtitle{}%
-  \gdef\beamer@frametitle{}%
-  \gdef\beamer@shortframetitle{}%
-  \gdef\beamer@framesubtitle{}%
-  \let\beamer@startcomment=\beamer@startcommentinframe%
-  % Start slide:
-  \beamer@framenotesbegin%
-    \global\setbox\beamer@framebox=\vbox\bgroup%
-    \beamer@inframetrue%
-    \let\frame=\framelatex% inside frames, use LaTeX's \frame command
-    \begin{beamer@framepauses}%
-      \refcounter{framenumber}%use frame number for  \label
-      \ifbeamer@shrink%
-        \hsize=\beamer@shrinkfactorinv\hsize%
-        \textwidth=\beamer@shrinkfactorinv\textwidth%
-        \linewidth=\beamer@shrinkfactorinv\linewidth%
-      \fi%
-      % Insert labels if necessary:
-      \ifx\beamer@againname\@empty\else%
-        \nointerlineskip\vbox to0pt{\vss%
-        \label<\the\beamer@slideinframe>{\beamer@againname<\the\beamer@slideinframe>}%
-        \ifnum\beamer@slideinframe=1\relax%
-          \label<1>{\beamer@againname}%
-        \fi%
-        }\nointerlineskip%
-      \fi%
-      \ifx\beamer@framehypertargets\@empty\else%
-        \nointerlineskip\vbox to0pt{\vss%
-          \beamer@framehypertargets%
-          \global\let\beamer@framehypertargets\@empty%
-        }\nointerlineskip%
-      \fi%
-      \vskip-\parskip\vbox{}%
-      \ifbeamer@plainframe\nointerlineskip\fi%
-    \beamer@checkframetitle}%
-    {\par
-    \end{beamer@framepauses}%
-  \egroup%
-  \ifx\beamer@frametitle\@empty%
+\patchcmd\endbeamer@frameslide
+  {\setbox\beamer@frametitlebox=\box\voidb@x\else}
+  {%
     \setbox\beamer@frametitlebox=\vbox{%
       \vbox{}%
       {\parskip0pt\usebeamertemplate***{noframetitle}\vskip0.25em}%
     }%
-  \else%
+    \else
     \def\MRTbeam@temp{*}%
     \ifx\beamer@frametitle\MRTbeam@temp%
       \def\insertframetitle{}%
     \fi%
-    \setbox\beamer@frametitlebox=\vbox{%
-      \vbox{}%
-      {\parskip0pt\usebeamertemplate***{frametitle}\vskip0.25em}%
-    }%
-  \fi%
-  \ifbeamer@plainframe%
-    \beamer@frametextheight=\paperheight%
-  \else%
-    \beamer@frametextheight=\textheight%
-  \fi%
-  \advance\beamer@frametextheight by-\ht\beamer@frametitlebox%
-  \advance\beamer@frametextheight by-\dp\beamer@frametitlebox%
-  \advance\beamer@frametextheight by-\beamer@frametopskip%
-  \ifbeamer@shrink%
-    \beamer@shrinkframebox%
-  \fi%
-  \ifx\beamer@zoomer\@empty
-    \setbox\beamer@framebox=\vbox{%
-      \nobreak\vbox{}\nobreak\par\nobreak\beamer@entrycode\nobreak%
-      \nointerlineskip\unvbox\beamer@frametitlebox%
-      \nobreak%
-      \ifbeamer@autobreak%
-        \vskip\beamer@frametopskipautobreak%
-      \else%
-        \vskip\beamer@frametopskip%
-      \fi%
-      \nobreak%
-      \nointerlineskip\box\beamer@zoombox\nointerlineskip%
-      \nobreak%
-      \ifbeamer@slidehaszoom\box\beamer@framebox\else\unvbox\beamer@framebox\fi%
-      % bottom skip is added in autobreakframebox
-    }%
-    \beamer@autobreakframebox%
-  \else%
-    \beamer@zoomer%
-  \fi%
-  \beamer@undolabels%
-  \beamer@framenotesend%
-  \box\beamer@framebox}
+  }
+  {}
+  {\PackageError{MRTbeam}{Failed to patch beamer's frameslide}{}}
 %=<<
 
 \setbeamertemplate{footline}{%>>=