%\iffalse
%<*copyright>
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% ltx4yt.sty package,                                  %%
%% Copyright (C) 2020                                   %%
%%   dpstory@uakron.edu                                 %%
%%                                                      %%
%% This program can 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 (at your option) any later version.      %%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%</copyright>
%<package>\NeedsTeXFormat{LaTeX2e}[1997/12/01]
%<package>\ProvidesPackage{ltx4yt}
%<package> [2020/07/30 v0.7 ltx4yt: Play YouTube videos in the default browser (dps)]
%<*driver>
\documentclass{ltxdoc}
\usepackage[colorlinks,hyperindex=false]{hyperref}
\hypersetup{pdfpagemode=useNone}
\usepackage{fancyvrb}
%\def\texorpdfstring#1#2{#1}
%\pdfstringdefDisableCommands{\let\\\textbackslash}
\OnlyDescription  % comment out for implementation details
\EnableCrossrefs
\CodelineIndex
\RecordChanges
\InputIfFileExists{aebdocfmt.def}{\PackageInfo{ltx4yt}{Inputting aebdocfmt.def}}
    {\def\IndexOpt{\DescribeMacro}\def\IndexKey{\DescribeMacro}\let\setupFullwidth\relax
     \PackageInfo{ltx4yt}{aebdocfmt.def cannot be found}}
\EnableCrossrefs \CodelineIndex \RecordChanges
\makeatletter
\renewcommand{\paragraph}
    {\@startsection{paragraph}{4}{0pt}{6pt}{-3pt}
    {\normalfont\normalsize\bfseries}}
\renewenvironment{quote}[1][]
   {\def\@rgi{#1}\ifx\@rgi\@empty
    \let\rghtm\@empty\else\def\rghtm{\rightmargin\leftmargin}\fi
    \list{}{\rghtm} %{\rightmargin\leftmargin}%
    \item\relax}
   {\endlist}
\makeatother
\bgroup\ttfamily
\gdef\brpr#1{\char123\relax#1\char125\relax}\egroup
\let\darg\brpr
\let\env\texttt
\let\opt\texttt
\let\app\textsf
\let\tops\texorpdfstring
\def\nmpsep#1{\hskip-\marginparsep\texttt{#1}}
\def\visispace{\symbol{32}}
\def\ameta#1{\ensuremath{\langle\textit{\texttt{#1}}\rangle}}
\def\meta#1{\textsl{\texttt{#1}}}
\def\SUB#1{\ensuremath{{}_{\mbox{\scriptsize\ttfamily#1}}}}
\def\ltag{<}\def\rtag{>}
\def\EXCL{!}
\let\app\textsf\let\pkg\textsf
\begin{document}
  \GetFileInfo{ltx4yt.sty}
  \title{The \textsf{ltx4yt} Package}
  \author{D. P. Story\\
    Email: \texttt{dpstory@acrotex.net}}
  \date{processed \today}
  \maketitle
  \tableofcontents
  \let\Email\texttt
  \DocInput{ltx4yt.dtx}
\IfFileExists{\jobname.ind}{\newpage\setupFullwidth\par\PrintIndex}{\paragraph*{Index} The index goes here.\\Execute
    \texttt{makeindex -s gind.ist -o ltx4yt.ind ltx4yt.idx} on the command line and recompile
    \texttt{ltx4yt.dtx}.}
\IfFileExists{\jobname.gls}{\PrintChanges}{\paragraph*{Change History} The list of changes goes here.\\Execute
    \texttt{makeindex -s gglo.ist -o ltx4yt.gls ltx4yt.glo} on the command line and recompile
    \texttt{ltx4yt.dtx}.}
\end{document}
%</driver>
% \fi
% \MakeShortVerb{|}
% \InputIfFileExists{aebdonotindex.def}{\PackageInfo{ltx4yt}{Inputting aebdonotindex.def}}
%    {\PackageInfo{ltx4yt}{cannot find aebdonotindex.def}}
%    \DoNotIndex{\g@addto@macro,\divide,\box,\setbox,\x,\y,\z}
%
%    \begin{macrocode}
%<*package>
%    \end{macrocode}
%
% \section{Introduction}
%
% It is July 2020 and Adobe's support for Flash will vanish in December. Google stopped
% supporting Flash several years ago, so the package \pkg{yt4pdf} is no longer functional
% and will be withdrawn from CTAN. If we cannot play videos within PDF anymore, the next best
% course is to develop some basic commands for playing YouTube videos in the default browser, preferably
% without any annoying advertisements. This can be done for some videos, but for others it cannot be done.
%
%\changes{v0.1}{2020/07/17}{Begin new package \string\pkg{ltx4yt}}
%\changes{v0.2}{2020/07/17}{Commands to pass arguments to urls}
%\changes{v0.6}{2020/07/25}{Final version before first publication}
%\changes{v0.7}{2020/07/30}{Corrected upload}
%    \begin{macrocode}
\RequirePackage{xkeyval}
%    \end{macrocode}
%    \leavevmode\IndexOpt{usepopup} When this option is taken, additional code to support
%    the use of popup menus is input. We also support \IndexOpt[\protect\EXCL]{!usepopup}\opt{!popup},
%    which is a convenience option for not using \opt{usepopup}.
%    \begin{macrocode}
\DeclareOption{usepopup}{\def\lo@dpu{\InputIfFileExists{ytpu.def}
  {\PackageInfo{ltx4yt}{Loading ytpu.def}}
  {\PackageInfo{ltx4yt}{Can't find ytpu.def}}}}
\DeclareOption{!usepopup}{}
\let\lo@dpu\relax
\AtEndOfPackage{\lo@dpu}
\ProcessOptions
\RequirePackage{xcolor}
\RequirePackage{eforms}
%    \end{macrocode}
%    If the \opt{usepopup} option is taken, we load the \pkg{popupmenu} package.
%    \begin{macrocode}
\ifx\lo@dpu\relax\else
\def\YT@rpPU{\RequirePackage{popupmenu}[2020/07/26]}\expandafter
\YT@rpPU\fi
%    \end{macrocode}
%
% \section{Implementation}
%
% The JavaScript method \texttt{app.launchURL\darg{\ameta{URL}}} is used to open the default browser
% on the page determined by \ameta{URL}. The links created use \cs{URI} (\texttt{/S/URI/URI}), this action type
% allows links to be functional in all PDF viewers, even on hand held devices.
%
% We have three implementations of this plan: (1)~links (\cs{ytvId} and \cs{ytLink}) for all devices;
% (2)~dropdown menus (combo boxes) (\cs{ytComboList} (uses JavaScript);
% and (3)~pop-up menus using the \env{popupmenu} environment of the \pkg{popupmenu} package (uses JavaScript).
% The methods that use JavaScript will not function in the near future on hand held devices.
%
% \subsection{Playing a YouTube video from its Video ID}
%
% In this section, we create several ways of calling for a YouTube video to play
% in the default browser.
%
% \subsubsection{Using a Link}
%    \begin{macro}{\ytvIdPresets}\nmpsep{\darg{\ameta{KV-pairs}}}
% The options for the \cs{ytvId} link. The default is given below in the definition.
% Initially, the preset is to produce \texttt{webbrown} colored links.
%    \begin{macrocode}
\newcommand{\ytvIdPresets}[1]{\def\yt@vIdPresets{#1}}
\definecolor{webbrown}{rgb}{.6,0,0} % from the web package
\ytvIdPresets{\linktxtcolor{webbrown}}
%    \end{macrocode}
%    \end{macro}
%    Here is a convenience command. This definition has since been made
%    in \pkg{insdljs}.
%    \begin{macrocode}
\providecommand{\URI}[1]{/S/URI/URI(#1)}
%    \end{macrocode}
%    Define \DescribeMacro\ytURL\cs{ytURL} to expand to the YouTube web site.
%    \begin{macrocode}
\def\ytNF{false}
\def\ytURL{https://www.youtube.com}
%    \end{macrocode}
%    \begin{macro}{\ytvId}\nmpsep{*[\ameta{opts}]\darg{\ameta{ytvID}}\darg{\ameta{text}}}
% The \cs{ytvId} is link which when pressed plays the video whose Video Id is \ameta{ytvID})
% in the default browser.
% \begin{quote}
% \begin{itemize}
%   \item[\texttt*] If the \texttt*-option is taken, you have determined that this
%   video cannot be embedded (which is the ideal) and must be played normally on YouTube
%   with all advertisements and other extraneous information.
%   \item[{\ameta{opts}}:] link optional KV-pairs to modify the appearance of the link.
%   \item[{\ameta{ytvID}}:] The video Id for the YouTube video to play
%   \item[{\ameta{text}}:] The text that displays the link.
%\end{itemize}
%\end{quote}
%    \begin{macrocode}
\newcommand{\ytvId}{\@ifstar{\def\yt@ask{*}\yt@@vId}
  {\let\yt@ask\@empty\yt@@vId}}
\newcommand{\yt@@vId}[3][]{%
  \ifx\yt@ask\@empty
    \def\yt@lnk@hash{embed/#2}\else
    \def\yt@lnk@hash{watch?v=#2}\fi
  \setLink[\presets{\yt@vIdPresets}#1
    \A{\URI{\ytURL/\yt@lnk@hash}}]{#3}%
}
%    \end{macrocode}
%    \end{macro}
%    \begin{macro}{\ytvIdML}\nmpsep{*[\ameta{opts}]\darg{\ameta{ytvID}}\darg{\ameta{text}}}
% The \cs{ytvId} is link which when pressed plays the video whose Video Id is \ameta{ytvID})
% in the default browser. This is a multi-line link, it requires the \pkg{aeb\_mlink} package
% and the \app{dvips\,\texttt{->}\,distiller} workflow.
%    \begin{macrocode}
\newcommand{\ytvIdML}{\@ifstar{\def\yt@ask{*}\yt@@vIdML}
  {\let\yt@ask\@empty\yt@@vIdML}}
\newcommand{\yt@@vIdML}[3][]{%
  \ifx\yt@ask\@empty
    \def\yt@lnk@hash{embed/#2}\else
    \def\yt@lnk@hash{watch?v=#2}\fi
  \mlsetLink[\presets{\yt@vIdPresets}#1
    \A{\URI{\ytURL/\yt@lnk@hash}}]{#3}%
}
%    \end{macrocode}
%    \end{macro}
%    \begin{macro}{\ytLink}\nmpsep{[\ameta{opts}]\darg{\ameta{spec}}\darg{\ameta{text}}}
%    We create a custom link for youtube videos. The \ameta{spec} (specification) argument has several
%    forms for maximum convenience and flexibility.
%    \begin{itemize}
%     \item |\ytLink{\embedId{|\ameta{ytvID}|}\params{|\ameta{parameters}|}}{|\ameta{text}|}|\\[3pt] This is the form
%     for playing a video with \ameta{ytvID} that \emph{can be embedded} (this best type of video). The \cs{params}
%     argument must follow the \cs{embedId}, its argument are any parameters you want to append to the URL.
%     The use of \cs{params} is optional; however, without the \cs{params} you may as well use
%     |\ytvId{|\ameta{ytvID}|}{|\ameta{text}|}|.
%
%     \item |\ytLink{\watchId{|\ameta{ytvID}|}\params{|\ameta{parameters}|}}{|\ameta{text}|}|\\[3pt] This is the form
%     for playing a video with \ameta{ytvID} that \emph{cannot be embedded} (advertisements and other information
%     appears). The \cs{params} argument must follow the \cs{watchId}, its argument are any parameters you want to append to the URL.
%     The use of \cs{params} is optional; however, without the \cs{params} you may as well use
%     |\ytvId*{|\ameta{ytvID}|}{|\ameta{text}|}|.
%
%     \item |\ytLink{\embed{|\ameta{spec}|}}{|\ameta{text}|}|\\[3pt]
%     A form that does not specify a video ID. It is useful for more general actions, such as
%     searches, for example,
%     \begin{flushleft}
%       |\ytLink{\embed{listType=search&list=Adobe Acrobat DC}}|\\
%       \qquad|{Search for Adobe Acrobat DC}|
%     \end{flushleft}
%     This form does not have a \cs{params} optional argument as all the parameters are built into the
%     argument of \cs{embed}.
%
%    \item |\ytLink{|\ameta{spec}|}{|\ameta{text}|}|\\[3pt] The most general form. The action of this
%    link is |\URI{\ytURL/|\ameta{spec}|}|; for example,
%     \begin{flushleft}
%       |\ytLink{embed?listType=search&list=Adobe Acrobat DC}|\\
%       \qquad|{Search for Adobe Acrobat DC}|
%     \end{flushleft}
%     Here you are free to build whatever URL you can imagine.
%
%    \item |\ytLink{\channel{|\ameta{name}|}}{|\ameta{text}|}|\\[3pt]
%    Such a link displays the channel \ameta{name}. For example,
%     \begin{flushleft}
%       |\ytLink{\channel{rocketjump}}{The RocketJump Channel}|
%     \end{flushleft}
%     This link opens the YouTube channel named \texttt{rocketjump}.
%    \end{itemize}
%   \paragraph*{Passing Player Parameters.}
%   As was illustrated above, the custom link \cs{ytLink} can pass various recognizable
%   parameters to YouTube. After reviewing,
%   \begin{flushleft}
%   \url{https://developers.google.com/youtube/player_parameters#Parameters}
%   \end{flushleft}
%   the following parameters are recommended, some of them are illustrated in the
%   sample document \texttt{ltx4yt-1.tex}:
%   \begin{itemize}
%     \item \texttt{autoplay=\ameta{\upshape{0\string|1}}} (default \texttt{0})
%     \item \texttt{controls=\ameta{\upshape{0\string|1}}} (default \texttt{1})
%     \item \texttt{fs=\ameta{\upshape{0\string|1}}} (default \texttt{1})
%     \item \texttt{modestbranding=\ameta{\upshape{0\string|0}}}
%     \item \texttt{playlist=\ameta{list}}
%     \item \texttt{listType=search\&list=\ameta{query}}
%   \end{itemize}
%   The specialized needs of the document author is most easily accommodated through the use
%   of the \cs{ytLink} command, for example,
%   \begin{flushleft}\obeylines
%     |\ytLink{\embedId{5y9-EVmreU4}\params{autoplay=1&modestbranding=1}}|
%     \qquad|{Lori's Corner: Episode \#1}|
%   \end{flushleft}
%    \begin{macrocode}
\newif\ifytwatch \ytwatchfalse
%    \end{macrocode}
%    \paragraph*{The \cs{ytLink} command.} Before getting to \cs{ytLink} an d\cs{ytLinkML},
%    there is a long stream of commands to parse the \ameta{spec} argument of \cs{ytLink}.
%    It goes through looking for \cs{watchId}, \cs{embedId}, \cs{embed}, and \cs{params}.
%    As it progresses, it adds code to the macro \cs{ytspec}, which at the end of things
%    will hold the fully formed \ameta{spec} for insertion into the URL.
%    \begin{macrocode}
\def\yt@@parse{\let\ytspec\@empty\yt@parse}
\def\yt@parse{\@ifnextchar\@nil{\@gobble}{\yt@parsei}}
\def\yt@parsei{\@ifnextchar\watchId{% check for \watchId
  \ytwatchtrue\yt@parse@watch}{\yt@parseii}}
\def\yt@parse@watch\watchId#1{\g@addto@macro
  \ytspec{\watchId{#1}}\yt@parse}
\def\yt@parseii{\@ifnextchar\embedId{% check for \embedId
  \yt@parse@embedId}{\yt@parseiii}}
\def\yt@parse@embedId\embedId#1{\g@addto@macro
  \ytspec{\embedId{#1}}\yt@parse}
\def\yt@parseiii{\@ifnextchar\embed{% check for \embed
  \yt@parse@embed}{\yt@parseiv}}
\def\yt@parse@embed\embed#1{\g@addto@macro
  \ytspec{\embed{#1}}\yt@parse}
\def\yt@parseiv{\@ifnextchar\params{% check for \params
  \yt@parse@params}{\yt@parsev}}
\def\yt@parse@params\params#1{\ifytwatch
  \g@addto@macro\ytspec{&#1}\else
  \g@addto@macro\ytspec{?#1}\fi
  \yt@parse}
%    \end{macrocode}
%    If we get this far, \ameta{spec} is raw, has none
%    of the helper commands. So we just insert the
%    entire argument into \cs{ytspec}.
%    \begin{macrocode}
\def\yt@parsev#1\@nil{\g@addto@macro\ytspec{#1}}
%    \end{macrocode}
%    All preliminaries done, we define \cs{ytLink}
%    \begin{macrocode}
\newcommand{\ytLink}[3][]{\begingroup
  \def\embedId##1{embed/##1}%
  \def\params##1{##1}\def\embed##1{embed?##1}%
  \def\watchId##1{watch?v=##1}\def\channel##1{c/##1}%
  \def\user##1{user/##1}%
  \yt@@parse#2\@nil % returns arg in \ytspec
  \def\URLArg{\ytURL/\ytspec}%
  \setLink[\presets{\yt@vIdPresets}#1\A{\URI{\URLArg}}
  ]{#3}\endgroup
}
%    \end{macrocode}
%    \end{macro}
%    \begin{macro}{\ytLinkML}\nmpsep{[\ameta{opts}]\darg{\ameta{spec}}\darg{\ameta{text}}}
%    is the multi-line version of \cs{ytLink}. It requires a \app{dvips\,\texttt{->}\,distiller} workflow
%    as well as the \pkg{aeb\_mlink} package.
%    \begin{macrocode}
\newcommand{\ytLinkML}[3][]{\begingroup
  \def\embedId##1{embed/##1}%
  \def\params##1{##1}\def\embed##1{embed?##1}%
  \def\watchId##1{watch?v=##1}\def\channel##1{c/##1}%
  \def\user##1{user/##1}%
  \yt@@parse#2\@nil % returns arg in \ytspec
  \def\URLArg{\ytURL/\ytspec}%
  \mlsetLink[\presets{\yt@vIdPresets}#1
    \A{\URI{\URLArg}}
  ]{#3}\endgroup
}
%    \end{macrocode}
%    \end{macro}
% \subsubsection{Using a Combobox}
%   All commands associate with a combo box play list.
%    \begin{macro}{\ytComboList}\nmpsep{[\ameta{opts}]\darg{\ameta{name}}\darg{\ameta{wd}}\darg{\ameta{ht}}}
% The \cs{ytComboList} command produces a combo box (dropdown menu) of video Ids and titles. The user selects a
% video based on its title, then presses the PLAY button. The two commands
% \cs{ytComboListPresets} and \cs{ytComboBtnPresets} are used to set the appearances
% of the combo box and the PLAY button.
%\begin{quote}
%\begin{itemize}
%   \item[\ameta{opts}:] eforms key-value pairs
%   \item[\ameta{name}:] A unique name (ASCII letters and numbers)
%   \item[\ameta{wd}:] The width of the combo box
%   \item[\ameta{ht}:] The height of the combo box
%\end{itemize}
%\end{quote}
% Now we have the code for \cs{ytComboList}
%    \begin{macrocode}
\newcommand{\ytComboList}[4][]{%
  \comboBox[\Ff{\FfCommitOnSelChange}\DV{\yt@pl@def}\V{\yt@pl@def}
    \presets{\yt@ComboListPresets}#1]{ytSelect#2}
  {#3}{#4}{*\yt@pl@pl}% 2020/07/22 v0.4
}
%    \end{macrocode}
%    \end{macro}
%    \begin{macro}{\ytComboBtn}\nmpsep{[\ameta{opts}]\darg{\ameta{name}}\darg{\ameta{wd}}\darg{\ameta{ht}}}
% A button to play the selection made in the combo box. The caption of the push button
% is determined by the command \DescribeMacro\ytStrPLAY\cs{ytStrPlay}.
% The parameters for \cs{ytComboBtn} are,
% \begin{quote}
%\begin{itemize}
%   \item[\ameta{opts}:] The KV-pairs to pass to the underlying push button.
%   \item[\ameta{name}:] A unique name (ASCII letters and numbers)
%   \item[\ameta{wd}:] The width of the combo box
%   \item[\ameta{ht}:] The height of the combo box
%\end{itemize}
%\end{quote}
%    \begin{macrocode}
\newcommand{\ytStrPLAY}{PLAY}
\newcommand{\ytComboBtn}[4][]{%
  \pushButton[\TU{Click to play}\CA{\ytStrPLAY}
    \presets{\yt@ComboBtnPresets}#1
    \A{\JS{var f=this.getField("ytSelect#2");\r
    var ytID=f.value;\r
    var i=f.currentValueIndices;\r
    var ytFV=f.getItemAt(i,false);\r
    var i=ytFV.indexOf("*");\r
    if ( i == -1 )\r\t
      app.launchURL("\ytURL/embed/"+ytID,\ytNF);\r
    else\r\t
      app.launchURL("\ytURL/watch?v="+ytID,\ytNF);
  }}]{ytSelectBtn#2}{#3}{#4}%
}
%    \end{macrocode}
%    \end{macro}
%    \begin{macro}{\ytPlayList}\nmpsep{\darg{\ameta{ytvID}}\darg{\ameta{\cs{cmd}}}}
% This command is executed before \cs{ytComboList} to set the initial/default value (\ameta{ytvID}) of the
% combo box and the play list (\ameta{\cs{cmd}}). Here \ameta{\cs{cmd}} is a command defined by the
% \cs{declarePlayList} command. Use the \cs{ytPlayList} to pass the play list to the next combo box.
%    \begin{macrocode}
\newcommand{\ytPlayList}{\begingroup\@makeother\_\@makeother\'
    \ytPlayList@i}
\def\ytPlayList@i#1#2{\gdef\yt@pl@def{#1}\xdef\yt@pl@pl{#2}\endgroup}
%    \end{macrocode}
%    \end{macro}
%    \begin{macro}{\ytComboListPresets}\nmpsep{\darg{\ameta{opts}}} The KV-pairs
%    for \cs{ytComboList}.
%    \begin{macrocode}
\newcommand{\ytComboListPresets}[1]{\def\yt@ComboListPresets{#1}}
\let\yt@ComboListPresets\@empty
%    \end{macrocode}
%    \end{macro}
%    \begin{macro}{\ytComboBtnPresets}\nmpsep{\darg{\ameta{opts}}} The KV-pairs
%    for \cs{ytComboBtn}.
%    \begin{macrocode}
\newcommand{\ytComboBtnPresets}[1]{\def\yt@ComboBtnPresets{#1}}
\let\yt@ComboBtnPresets\@empty
%    \end{macrocode}
%    \end{macro}
%    \leavevmode\DescribeMacro{\ytIdTitle}\nmpsep{\darg{\ameta{text}}\darg{\ameta{VidID}}}
%     A convenience command to lay out the playlist.
%    \begin{macrocode}
\newcommand{\ytIdTitle}[2]{[(#2)(#1)]}
%    \end{macrocode}
%    \begin{macro}{\declarePlayList}
%    A video ID may contain characters {\LaTeX} considers special, so we sanitize these
%    special characters before reading in the video ID. Near as I can determine, a video
%    id consists of 11 characters comprising combinations of letters (A-Z,a-z) numbers
%    (0-9) and special characters underscore and hyphen (\_ and -). We sanitize the last two.
%\begin{Verbatim}[xleftmargin=\parindent,codes={\catcode`\%=9},commandchars={!()}]
%\declarePlayList{!ameta(\cmd)}{
%   \ytIdTitle{!ameta(text)}{!ameta(VidID)}
%   ...
%   \ytIdTitle{!ameta(text)}{!ameta(VidID)}
% }
%\end{Verbatim}
%The entries may also be in raw form `|[(\ameta{VidID})(\ameta{text})]|'. Note that the two arguments are
%enclosed in parentheses, there is a problem with parsing if \ameta{text} itself contains
%parentheses. Within \ameta{text} enclose matching parentheses in braces, for example,
%\begin{flushleft}|\ytIdTitle{Kung-Fu Fighting {(Bruce Lee version)}}{GZ9e3Dy7obA}|\end{flushleft}
%\paragraph*{The role of \texttt* in the title.} If an \texttt{*} appears in the title, this means
%that the video cannot be embedded. Viewing the video will come with advertisements and other information
%that YouTube generates.
%\begin{flushleft}|\ytIdTitle{Kung-Fu Fighting* {(Original version)}}{jhUkGIsKvn0}|\end{flushleft}
%\changes{v0.4}{2020/07/22}{Changed parsing of \string\cs{declarePlayList} to accomodate
%\string\cs{pdfstringdef}}
%    \begin{macrocode}
\newcommand{\declarePlayList}[1]{\bgroup
  \Hy@unicodefalse
  \let\pl@yList\@empty
  \ifpdfmarkup
    \def\Esc{\eqbs}\else\def\Esc{}\fi
  \def\cs##1{\eqbs\eqbs##1}\relax
  \@makeother\_\@makeother\-
  \yt@declarePlayList{#1}%
}
\def\yt@declarePlayList#1#2{%
  \yt@declarePlayList@i#2\@nil\relax\relax
  \toks@=\expandafter{\pl@yList}\relax
  \xdef#1{\pl@yList}\egroup
}
\def\yt@declarePlayList@i{\@ifnextchar\@nil
  {\expandafter\@gobbletwo\@gobble}
  {\yt@declarePlayList@ii}%
}
\def\yt@declarePlayList@ii\ytIdTitle#1#2{%
  \pdfstringdef\yt@PLTitle{#1}%
  \edef\y{[(#2)(\yt@PLTitle)]}%
  \expandafter\g@addto@macro\expandafter
    \pl@yList\expandafter{\y}%
  \yt@declarePlayList@i
}
%    \end{macrocode}
%    \end{macro}
%An example of use of \cs{declarePlayList}:
%\begin{Verbatim}[xleftmargin=\parindent,codes={\catcode`\%=9},commandchars={!()}]
%\declarePlayList{\playListii}{%
%  \ytIdTitle{Elfego Baca}{gRwa0MdeqVs}
%  \ytIdTitle{Texas John Slaughter}{7yrk1BvtLE8}
%  \ytIdTitle{Swamp Fox}{-SBPnw5riLM&NR}
%  \ytIdTitle{Zorro Promo}{cKludhxEoJ0}
%}
%\end{Verbatim}
%    \begin{macrocode}
%</package>
%<*pujs>
%    \end{macrocode}
% \subsubsection{Using a popup menu}
%    These code lines (including the document JavaScript) are only included
%    when the \opt{usepopup} option is taken.
%    \begin{macro}{\ytUseMenus}\nmpsep{\darg{\ameta{menu-names}}}
% A command used to list popupmenu data. It defines a command
% \cs{ytPopupData} that is used in the JS support for popup menus. The argument
% \ameta{menu-names} is a comma-delimited list of menu names defined by a \env{popupmenu} environment. The command
% needs to be in the preamble.
%    \begin{macrocode}
\def\ytPopupAllMenuData{// ltx4yt: Begin popup menu data^^J}%
\let\ytMenuNames\@gobble
\newcommand{\ytUseMenus}[1]{\bgroup
  \@for\yt@menu:=#1\do{%
    \edef\x{\noexpand\g@addto@macro\noexpand
      \ytMenuNames{,"\yt@menu"}}\x
    \edef\x{\expandafter\noexpand\@nameuse{\yt@menu}}%
    \toks@=\expandafter{\x^^J}%
    \expandafter\g@addto@macro\expandafter
      \ytPopupAllMenuData\expandafter{\the\toks@}%
  }\g@addto@macro\ytPopupAllMenuData
    {// ltx4yt: End of popup menu data}%
  \egroup
}
\@onlypreamble\ytUseMenus
%    \end{macrocode}
%    \end{macro}
%    \begin{macro}{\puIdTitle}
% A convenience macro for entering popupmenu data for youtube videos.
%\begin{Verbatim}[xleftmargin=\parindent,fontsize=\small,codes={\catcode`\%=9},commandchars={!()}]
%\begin{popupmenu}{YTMenu}
%  \puIdTitle{Select a YouTube Video}{} % A title has no yt Id
%  \begin{submenu}{title=Music Videos}
%     \puIdTitle{Kung-Fu Fighting (Bruce Lee version)}{GZ9e3Dy7obA}
%     \puIdTitle{\string\"Sea Hunt\string\" TV serie}{MW-IZ67iADU}
%     ...
%   \end{submenu}
%\end{popupmenu}
%\end{Verbatim}
% Note that we must protect the double quote.
%    \begin{macrocode}
%\newcommand{\puIdTitle}[2]{\item{title={#1},%
%  return={[\itemindex,'#2']}}}
\newcommand{\puIdTitle}[2]{\Hy@unicodefalse\pdfstringdef\x@YT{#1}%
  \edef\y@YT{\noexpand\item{title={\x@YT},%
  return={[\noexpand\itemindex,'#2']}}}\y@YT}
%    \end{macrocode}
%    \end{macro}
%    Some convenience commands for setting up a push button to display the popupmenu
%    on rollover.
%    \begin{macrocode}
\def\ytpubtnCnt{0}
\newcommand{\ytPopupBtn}[4][]{\bgroup
  \@tempcnta\ytpubtnCnt\relax
  \advance\@tempcnta\@ne
  \xdef\ytpubtnCnt{\the\@tempcnta}%
  \pushButton[\cmd{\pmpvCAOff}\CA{YT Menu}
  \textColor{0 0 1}\W1\BC{}\textSize{0}
    \H{N}\S{S}\presets{\yt@PopupPresets}#1
    \AAmouseenter{ytPopupMenu("#2");} % dps
    ]{ytPopup\ytpubtnCnt}{#3}{#4}\egroup
}
\newcommand{\ytPopupPresets}[1]{\def\yt@PopupPresets{#1}}
\let\yt@PopupPresets\@empty
%    \end{macrocode}
%    \begin{macrocode}
%</pujs>
%<*package>
%    \end{macrocode}
% \subsection{Search YouTube interactively}
%    \begin{macro}{\ytInputQuery}\nmpsep{[\ameta{opts}]\darg{\ameta{wd}}\darg{\ameta{ht}}}
%    Provides a text field to enter a query string.
%    \begin{macrocode}
\newcommand{\ytInputQuery}[3][]{%
  \textField[\TU{Enter a query text string}#1]{ytSearchTxt}{#2}{#3}}
%    \end{macrocode}
%    \end{macro}
%    \begin{macro}{\ytSearch}\nmpsep{[\ameta{opts}]\darg{\ameta{wd}}\darg{\ameta{ht}}}
%    A push button what will search YouTube based on the query string.
%    \begin{macrocode}
\newcommand{\ytSearch}[3][]{%
  \pushButton[\CA{Search}#1\AAmouseup{%
    var f=this.getField("ytSearchTxt");\r
    var v=f.value;\r
    if ( v.replace(/\string\s/g,"") != "" )\r\t
      app.launchURL("\ytURL/embed?listType=search&list="+v);}
  ]{ytSearchBtn}{#2}{#3}}
%    \end{macrocode}
%    \end{macro}
%    \begin{macro}{\ytClearQuery}\nmpsep{[\ameta{opts}]\darg{\ameta{wd}}\darg{\ameta{ht}}}
%    A button to clear the query string.
%    \begin{macrocode}
\newcommand{\ytClearQuery}[3][]{%
  \pushButton[\CA{Clear}#1
    \AAmouseup{this.resetForm("ytSearchTxt");}
  ]{ytSearchClr}{#2}{#3}%
}
%    \end{macrocode}
%    \end{macro}
%    \begin{macrocode}
%</package>
%<*pujs>
%    \end{macrocode}
%\subsection{Document JavaScript}
%    Some JavaScript to process the user's choice and to launch the browser
%    to view the selected video.
%    \changes{v0.5}{2020/07/24}{Manage multiple menus}
%    \begin{macrocode}
\begin{insDLJS*}{yt}
\begin{newsegment}{ltx4yt: %
Popup Menu Data and JavaScript support functions}
var YTdebug=false;
var aYTLastChoice=new Array;
var bYTLastChoice=false;
\ytPopupAllMenuData
var aChoice; // make local
function ytProcessMenu(cMenu) { // aMenu->cMenu now a string
  var aMenu=eval(cMenu);
  var cChoice = app.popUpMenuEx.apply( app, aMenu );
  ytProcessMenu.cChoice=cChoice;
  if ( cChoice != null ) {
    aChoice=eval(cChoice);
    if (aChoice[1]=="") return null;
    var thisChoice=aChoice[0];
    eval(cMenu+thisChoice).bMarked=true;
    if (!bYTLastChoice) {
      eval(cMenu+aChoice[0]).bMarked=true;
    } else {
		  var structLoc=eval(aYTLastChoice[1])[0]
		  eval(aYTLastChoice[0]+structLoc).bMarked=false;	
      eval(cMenu+aChoice[0]).bMarked=true;
    }
    return aChoice;
  } else return null;
}
function ytPopupMenu(cMenu) { // cMenu now a string
  var aChoice=ytProcessMenu(cMenu);
  var cChoice=ytProcessMenu.cChoice;
  var aMenu=eval(cMenu);
  if (aChoice!=null) {
    var title=eval(cMenu+aChoice[0]).cName;
    var i=title.indexOf("*");
    var _hash=(i == -1)?"embed/"+aChoice[1]:"watch?v="+aChoice[1];
    if (!bYTLastChoice) {
      if(YTdebug) %
console.println("launching url https://www.youtube.com/"+_hash);
      else app.launchURL("https://www.youtube.com/"+_hash,false);
      aYTLastChoice=[cMenu,cChoice];
      bYTLastChoice=true;
    } else {
		var cLastMenu=eval(aYTLastChoice[1])[0]
      aYTLastChoice=[cMenu,cChoice];
      if (cLastMenu!=aChoice[0]) {
        if (YTdebug) %
console.println("will launch url: https://www.youtube.com/"+_hash);
        else app.launchURL("https://www.youtube.com/"+_hash,false);
      } else {
        if (YTdebug) console.println("will NOT launch url");
        // choice is the same, uncheck this item
        eval(cMenu+aChoice[0]).bMarked=false;
        bYTLastChoice=false;
      }
    }
  }
}
\end{newsegment}
\end{insDLJS*}
%    \end{macrocode}
%    \begin{macrocode}
%<*pujs>
%<*package>
%</package>
%    \end{macrocode}
%  \Finale
\endinput

https://developers.google.com/youtube/iframe_api_reference?csw=1
