Beamer zooming - change color and depth of zoom outline?

Question

I want to make the outline of the zoom feature bigger in the first slide where I can click on it.

I use this minimal working example:

\documentclass{beamer}
\begin{document}
\begin{frame}
    \framezoom<1><2>border(2cm,1.5cm) 
    \pgfimage[height=6cm]{example-grid-100x100bp.pdf}
\end{frame}
\end{document}

How can I make the outline double as broad and in the color of my "alert"?

Obviously I visited: Zooming in and highlighting part of picture

Answer 1

You could redefine the \beamer@framezoom macro. See the line I marked with % <- change here to change the colour and linewidth.

\documentclass{beamer}
\makeatletter
\def\beamer@framezoom<#1><#2>#3(#6,#7){%
  \par\nointerlineskip%
  \global\beamer@slidehaszoomtrue%
  \advance\beamer@zoomcount by1\relax%
  \def\beamer@zoomborderwidth{0}%
  \edef\beamer@labelzoomed{beamer@labelzoomed@\the\beamer@zoomframecount @\the\beamer@zoomcount}%
  \setkeys{beamerzoom}{#3}%
  \only<#1>{%
    {\hypersetup{pdfhighlight={/P},allbordercolors=alerted text.fg,pdfborder={0 0 3}}% <- change here
    \global\setbox@tempboxa=\vbox{\hyperlink{\beamer@labelzoomed}{%
      \expandafter\ifx\csname XeTeXrevision\endcsname\relax%
      \else%
        \special{pdf:xann width #6 height #7 depth 0pt}%
      \fi%
      \vbox to #7{%
        \hbox to#6{\hfil}%
        \vfil%
      }%
    }}}%
    \ht@tempboxa=0pt%
    \wd@tempboxa=0pt%
    \dp@tempboxa=0pt%
    \setbox@tempboxa=\vbox{\moveright#4\hbox{\lower#5\vbox{\box@tempboxa}}}%
    \ht@tempboxa=0pt%
    \wd@tempboxa=0pt%
    \dp@tempboxa=0pt%
    \global\setbox\beamer@zoombox=\vbox to0pt{\unvbox\beamer@zoombox\box@tempboxa}%
  }%
  \only<#2>{%
    @ifundefined{\beamer@labelzoomed}%
    {%
      \hypertarget{\beamer@labelzoomed}{}%
      \expandafter\gdef\csname\beamer@labelzoomed\endcsname{}%
    }{}%
    \gdef\beamer@zoomer{%
      % compute zoom factor
      @tempdima=\beamer@frametextheight%
      @tempdimb=#7\relax%
      @tempcnta=@tempdimb%
      \divide@tempcnta by4096\relax%
      \multiply@tempdima by16\relax%
      \divide@tempdima by@tempcnta%
      @tempdimb=\paperwidth%
      \ifbeamer@plainframe%
      \else%
        \advance@tempdimb by-\beamer@leftsidebar%
        \advance@tempdimb by-\beamer@rightsidebar\relax%
      \fi%
      @tempdimc=#6\relax%
      @tempcntb=@tempdimc%
      \divide@tempcntb by4096\relax%
      \multiply@tempdimb by16\relax%
      \divide@tempdimb by@tempcntb%
      \ifdim@tempdimb<@tempdima%
        @tempdima=@tempdimb%
      \fi%
      \edef\beamer@temp{\strip@pt@tempdima}%
      @tempdimc=\beamer@frametextheight%
      \advance@tempdimc by4pt%
      @tempdimb=\paperwidth%
      \ifbeamer@plainframe%
      \else%
        \advance@tempdimb by-\beamer@leftsidebar%
        \advance@tempdimb by-\beamer@rightsidebar\relax%
      \fi%
      \setbox@tempboxa=\vbox{\hsize=@tempdimb\Acrobatmenu{GoBack}{\vbox to
          \beamer@frametextheight{\hbox to@tempdimb{\hfil}\vfil}}}%
      \ht@tempboxa=0pt%
      \wd@tempboxa=0pt%
      \dp@tempboxa=0pt%
      \setbox\beamer@framebox=\vbox to\beamer@frametextheight{{%
          \ifbeamer@plainframe\beamer@leftmargin=\Gm@lmargin\fi%
          \begin{pgfpicture}{\beamer@leftmargin}{-\beamer@frametextheight}{\beamer@leftmargin}{0pt}
            \pgftext[left,top]{\box@tempboxa}
            \pgfpathrectangle{\pgfpoint{0pt}{-@tempdimc}}{\pgfpoint{@tempdimb}{@tempdimc}}%
            \pgfusepath{clip}
            \begingroup
              \pgftransformscale{\beamer@temp}
              @tempdima=#4\relax%
              @tempdimb=#5\relax%
              {\pgftransformshift{\pgfpoint{-@tempdima}{@tempdimb}}%
              \pgftext[left,top]{\vbox{\vbox{}\nointerlineskip\unvbox\beamer@framebox}}}
            \endgroup
          \end{pgfpicture}%
        }}%
      \setbox\beamer@framebox=\vbox{%
        \nobreak\vbox{}\nobreak\par\nobreak\beamer@entrycode\nobreak%
        \nointerlineskip\unvbox\beamer@frametitlebox%
        \nobreak%
        \box\beamer@framebox%
        \nobreak%
        \vss%
        \beamer@exitcode%
      }%
      \global\setbox\beamer@footins=\box\voidb@x% no footnotes in zoomed slides
    }%
  }%
}
\makeatother
\begin{document}
\begin{frame}
    \framezoom<1><2>border(2cm,1.5cm) 
    \pgfimage[height=6cm]{example-grid-100x100bp.pdf}
\end{frame}
\end{document}