path: root/macros/latex/contrib/tasks/tasks-manual.tex

% --------------------------------------------------------------------------
% the TASKS package
% 
%   lists with columns filled horizontally
% 
% --------------------------------------------------------------------------
% Clemens Niederberger
% Web:    https://github.com/cgnieder/tasks/
% E-Mail: contact@mychemistry.eu
% --------------------------------------------------------------------------
% Copyright 2013--2021 Clemens Niederberger
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% This work may be distributed and/or modified under the
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% The Current Maintainer of this work is Clemens Niederberger.
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% If you have any ideas, questions, suggestions or bugs to report, please
% feel free to contact me.
% --------------------------------------------------------------------------
\documentclass{tasks-manual}

\begin{document}

\section{Preface}
\subsection{Motivation \& History}
Originally \Tasks\ has been an integral part of the
\ExSheets\changedversion{0.7} package~\cite{pkg:exsheets}.  However, users
told me that it indeed could be useful to have it as a stand-alone package not
having to load the whole \ExSheets\ beast just for having the \env{tasks}
environment available.  Since I agree with this the environment has been
extracted into a package if its own, \Tasks.  Since then \Tasks\ has been
distributed as a package of its own but as part of the \ExSheets\
bundle\changedversion{0.10}.  With v0.10 I decided to make it a completely
independent package.  So the relation to \ExSheets\ only is a historical one.

The reason for the \env{tasks} environment is an unwritten agreement in German
maths textbooks (exspecially in (junior) high school textbooks) to organize
exercises in columns counting horizontally rather than vertically.  That is
what \code{tasks} primarily is for. If you don't need this feature you're
better off using traditional \LaTeX\ lists and the \pkg{enumitem} package for
customization.

\subsection{Changes}
The \sinceversion{1.0} step to version~1.0 brought some significant changes:
\begin{itemize}
  \item the option \option{counter-format} is deprecated.  Labels can now be
    set quite similar to the way they are set in \pkg{enumitem}.  This also
    made the \code{enumerate} option of the list template superfluous which has
    been removed accordingly.
  \item The commands \cs{NewTasks} and \cs{RenewTasks} have been renamed.
  \item The multiple choice lists have been removed.
  \item Custom definitions can be put in a \code{tasks.cfg} file which is
    automatically loaded if available.
\end{itemize}

\section{License and Requirements}\label{sec:license}
\license

\Tasks\ requires the \bnd{l3kernel}~\cite{bnd:l3kernel} bundle,
\needpackage{xparse} and \pkg{xtemplate}.

\section{How it works}
\subsection{Background}
The \env{tasks} environment is similar to a list like \env{enumerate} but not
the same.  Here are some of the differences:
\begin{tasks}[style=enumerate]
  \task there is no pagebreak possible inside an item but only between items.
  \task the enumeration default is a), b), c) \ldots
  \task the body of the \env{tasks} environment is split at \emph{every}
    occurrence of the item separator.  For this reason the default separator
    is not \cs*{item} but \cs{task} so it is unique to this environment only.
    This directly leads to\ldots
  \task \ldots\ the fact that the \env{tasks} environment cannot be nested.
    You can, however, use an \env*{itemize} environment or another
    \enquote{real} list in it.
  \task A fifth difference: verbatim material cannot be used in it.  You'll
    have to use \cs*{string}, \cs*{texttt} or \cs*{detokenize}.  If this
    won't suffice then don't use \env{tasks}.
\end{tasks}

\begin{bewareofthedog}
  The environments of \Tasks\ are what I like to call
  \enquote{pseudo-environments}.  This means like environments defined by the
  package \pkg{environ}~\cite{pkg:environ} the body of the environment is read
  as argument before it is processed.  This is why verbatim material cannot be
  used in \Tasks' lists.
\end{bewareofthedog}

\subsection{The Basics}
\begin{environments}
  \environment{tasks}[\oarg{options}\darg{num of columns}]
    List like environment where the single items are introduced with
    \cs{task}.
\end{environments}
Let's see an example:
\begin{example}
  % \Sample is defined to contain some sample text:
  % \def\sample{This is some sample text we will use to create a somewhat
  %   longer text spanning a few lines.}
  % \def\Sample{\sample\ \sample\par\sample}
  Some text before the list.
  \begin{tasks}
    \task \Sample
    \task \Sample
    \task \Sample
  \end{tasks}
  And also some text after it.
\end{example}

The environment takes the optional argument \darg{num of columns} with which
the number of columns used by the environment is specified.
\begin{example}
  \begin{tasks}(2)
    \task \Sample
    \task \sample\ \sample
    \task \sample
    \task \Sample
    \task \sample\par\sample
  \end{tasks}
\end{example}

\subsection{Items Spanning More Than One Column}
Sometimes it may come in handy if an item is allowed to span more than one
column.  \Tasks\sinceversion{0.10} supports items using the remaining space by
adding an optional\label{optional-star} star to \cs{task}:
\begin{example}
  \begin{tasks}(3)
    \task \sample
    \task* \sample
    \task* \sample
    \task \sample
    \task \sample
  \end{tasks}
\end{example}

\Tasks\sinceversion{0.10} also supports items that span \emph{all} columns in
any case by adding an optional bang\label{optional-bang} to \cs{task}.
\begin{example}
  \begin{tasks}(3)
    \task \sample
    \task! \sample
    \task! \sample
    \task \sample
    \task \sample
  \end{tasks}
\end{example}

The optional star has itself an optional argument with parentheses where you
can specify the number of columns the item is supposed to span:\label{debug}
\begin{example}
  \settasks{debug}
  \begin{tasks}(4)
    \task the first
    \task the second
    \task the third
    \task the fourth
    \task*(3) the fifth item is way too long for this and needs three columns
    \task the sixth
    \task the seventh
    \task*(2) the eighth item is way too long for this and needs two columns
    \task the nineth
    \task the tenth
  \end{tasks}
\end{example}
If there are not enough columns left (say two columns but you said
\cs{task}\sarg\Darg{3}) the argument is ignored and the maximum number of
remaining columns is used (two in case of our example).

Both optional star and optional bang can be combined with the optional
argument for a custom label:
\begin{example}
  \begin{tasks}(3)
    \task \sample
    \task* \sample
    \task*[(x)] \sample
    \task \sample
    \task \sample
  \end{tasks}
\end{example}

Forcing a new item line manually is also possible\sinceversion{0.9} using the
following command:
\begin{commands}
  \command{startnewitemline}
    Introduce a new line in a \env{tasks} environment.
\end{commands}
While this works it also needs a bit of care since the width of the items
doesn't change which means in order to use the full width you'd have to use
trickery like \cs*{rlap} which then means the danger of the item text sticking
into the margin.

\begin{example}
  \begin{tasks}(4)
    \task the first
    \task the second
    \task the third
    \task the fourth
    \task \rlap{the fifth item is way too long for this so we start a new row}
      \startnewitemline 
    \task the sixth
    \task the seventh
    \task \rlap{the eighth item also is too long} \startnewitemline
    \task the nineth
    \task the tenth
  \end{tasks}
\end{example}

\section{Available Options}\label{sec:tasks:options}

The \Tasks\ package does not have any package options\changedversion{0.10}.

The environment \env{tasks} has a number of options, though, namely the
following ones that can be set using a setup command:
\begin{commands}
  \command{settasks}[\marg{options}]
    Setup command for \Tasks.
\end{commands}
\begin{options}
  \keyval{style}{instance}\Default
     Choose the instance to be used.  Read more on this in
     section~\ref{sec:tasks}.
  \keyval{label-format}{code}\Default
    \changedversion{1.1a}Can be used to apply a formatting like, \eg,
    \cs*{bfseries} to the labels.  This may be code accepting the item as
    mandatory argument.
  \keyval{label}{code}\Default{\cs*{alph}\code{*)}}
    \changedversion{1.0}Sets a custom label.  The \code{*} is replaced by
    \Marg{task}.  This is heavily inspired by
    \pkg{enumitem}'s~\cite{pkg:enumitem} \code{label} option.
  \keyval{ref}{code}\Default
    \sinceversion{1.3}Works like \option{label} but sets the output of the
    reference by setting \cs*{the\meta{counter}} (\cs{thetask} in the default
    setting).
  \keyval{label-width}{dim}\Default{1em}
    Sets the width of the item labels.
  \keyval{label-offset}{dim}\Default{.3333em}
    \sinceversion{0.7}Sets the offset, \ie, the distance between label and
    item.
  \keyval{item-format}{code}\Default
    \sinceversion{0.11}Can be used to apply a formatting like, \eg,
    \cs*{bfseries} to the items. This may be code accepting the item as
    mandatory argument.
  \keyval{item-indent}{dim}\Default{2.5em}
    \sinceversion{0.9a}The indent of an item, \ie, the horizontal space
    available for both label and label-offset.  If
    \[
      \text{\code{indent}} =
      \text{\code{label-width}} + \text{\code{label-offset}}
    \]
    the label will align with the textblock above (if
    \keyis{label-align}{left} is set).  Please see figure~\ref{fig:lengths}
    for a sketch of the available lengths and how they are set.
  \keyval{column-sep}{dim}\Default{0pt}
    \sinceversion{0.10}A horizontal length that is inserted between columns ot
    items.
  \keychoice{label-align}{left,right,center}\Default{left}
    \sinceversion{0.7}Determines how the labels are aligned within the
    label-box whose width is set with \option{label-width}.
  \keyval{before-skip}{skip}\Default{0pt}
    Sets the skip before the list.
  \keyval{after-skip}{skip}\Default{0pt}
    Sets the skip after the list.
  \keyval{after-item-skip}{skip}\Default{1ex plus 1ex minus 1ex}
    \sinceversion{0.9}This vertical skip is inserted between rows of items.
  \keybool{resume}\Default{false}
    The enumeration will resume from a previous \env{tasks} environment.  In
    order to use this option properly you shouldn't mix different \env{tasks}
    environments that both count their items.
  \keyval{start}{integer}\Default{1}
    \sinceversion{1.1}Set the starting value with which the list starts
    counting.
  \keyval{counter}{counter}\Default{task}
    \sinceversion{1.2}The counter to be used to count the items.
  \keybool{debug}\Default{false}
    \sinceversion{0.10}If set to true \cs*{fboxsep} is set to \code{0pt}
    inside the \env{tasks} environment and \cs*{fbox} is used to draw a frame
    around the label boxes and the item boxes.
\end{options}

\begin{figure}
  \centering
  \begin{tikzpicture}[every node/.style={font=\footnotesize},scale=.5]
    \coordinate (itemedge1) at (2,2) ;
    \coordinate (itemedge2) at (13,2) ;
    \draw
      (itemedge1) -- ++(8,0) -- ++(0,-2) -- ++(-8,0) -- cycle ;
    \draw
      (itemedge1) ++(-.5,0) coordinate(labeledge1)
      -- ++(-1,0) --++ (0,-1) --++(1,0) --++(0,1) ;
    \draw (itemedge1) ++(-2,0) -- ++(0,-2) ;
    \draw
      (itemedge2) -- ++(8,0) -- ++(0,-2) -- ++(-8,0) -- cycle ;
    \draw
      (itemedge2) ++(-.3,0) coordinate(labeledge2)
      -- ++(-1,0) --++ (0,-1) --++(1,0) --++(0,1) ;
    \draw (itemedge2) ++(-2,0) -- ++(0,-2) ;
    \draw[<->] (itemedge2) ++(-2,0) --node[above]{column sep} ++(-1,0) ;
    \draw[<->] (0,-.5) --node[below]{item indent} (2,-.5) ;
    \draw[<->] (2,-.5) --node[below]{item width} (10,-.5) ;
    \draw[<->] (labeledge1) ++(0,1) --node[above]{label width} ++(-1,0) ;
    \draw[<->] (labeledge1) --node[above]{label offset} ++(.5,0) ;
  \end{tikzpicture}
  \caption{A visual representation of the used lengths.}
  \label{fig:lengths}
\end{figure}

Now the same list as above but with three columns and a different label:
\begin{example}
  \begin{tasks}[label=(\roman*),label-width=4ex](2)
    \task \Sample
    \task \sample\ \sample
    \task \sample
    \task \Sample
    \task \sample\par\sample
  \end{tasks}
\end{example}

Let's use it inside a question, \ie, inside \pkg{xsim}'s \env{exercise}
environment~\cite{pkg:xsim}:
\begin{example}
  % since settings are local the following ones will be lost
  % outside this example;
  \settasks{
    label        = \theexercise.\arabic* ,
    item-indent  = 2em ,
    label-width  = 2em ,
    label-offset = 0pt
  }
  \begin{exercise}
    I have these two tasks for you. Shall we begin?
    \begin{tasks}(2)
      \task The first task: easy!
      \task The second task: even more so!
    \end{tasks}
  \end{exercise}
  \begin{solution}[print]
    Now, let's see\ldots\ ah, yes:
    \begin{tasks}
      \task This is the first solution. Told you it was easy.
      \task This is the second solution. And of course you knew that!
    \end{tasks}
  \end{solution}
\end{example}

Finally let's see what the \option{debug} option does (you could see it
already on page~\pageref{debug}):
\begin{example}
  \settasks{debug}
  \begin{tasks}(2)
    \task \Sample
    \task \Sample
  \end{tasks}
\end{example}

\section{Available Instances}\label{sec:tasks:instances}
There are currently three additional instances for the \code{tasks} object
available:
\begin{description}
  \item[itemize] uses \cs*{labelitemi} as labels.
  \item[enumerate] enumerates the items with 1., 2., \ldots
  % \item[multiplechoice] a --~well~-- `multiple choice' list.
\end{description}
\begin{example}
  \begin{tasks}[style=itemize](2)
    \task that's just how\ldots
    \task \ldots we expected
  \end{tasks}
  \begin{tasks}[style=enumerate](2)
    \task that's just how\ldots
    \task \ldots we expected
  \end{tasks}
\end{example}
  % \begin{tasks}[style=multiplechoice](2)
  %   \task that's just how\ldots
  %   \task \ldots we expected
  % \end{tasks}

\section{Custom Labels}
If you want to change a single label inside a list, you can use the optional
argument of \cs{task}. This will temporarily overwrite the default label.
\begin{example}[side-by-side]
  \begin{tasks}[style=itemize]
    \task a standard item
    \task another one
    \task[+] a different one
    \task and another one
  \end{tasks}
\end{example}

You've already seen examples for the \option{label} option.
\begin{options}
  \keyval{label}{code}\Default{\cs*{alph}\code{*)}}
    It can be used to set the label for a list.  A \code{*} inside is always
    replaced by the current counter name inside braces.  It can contain
    formatting instructions like \cs*{bfseries} but it can be cleaner to use
  \keyval{label-format}{code}\Default
    instead.  This is especially true since the \option{label} also sets
    \cs*{the\meta{counter}} where you usually don't want to have formatting
    instructions.  Another way to deal with this issue is the option
  \keyval{ref}{code}\Default
    which sets \cs*{the\meta{counter}} (\cs{thetask} in the default setting).
\end{options}

\begin{example}[side-by-side]
  \begin{tasks}[label=\arabic*.,ref=\arabic*]
    \task first item
    \task second item \label{foo}
  \end{tasks}
  See item~\ref{foo} without dot.
\end{example}

Two additional commands are defined which in some circumstances might prove
useful:
\begin{commands}
  \command{tasksifmeasuringTF}[\marg{true}\marg{false}]
    \sinceversion{1.2}This command used inside a label checks if the label is
    typeset for measuring its width or if it is typeset \enquote{for
      real}.  There are also the variants \cs{tasksifmeasuringT} and
    \cs{tasksifmeasuringF}.
  \command{tasklabel}
    \sinceversion{1.3}Holds the current label text.
\end{commands}

\section{New \code{tasks}-like Environments}
It is possible to add custom environments that work like the \code{tasks}
environment.
\begin{commands}
  \command{NewTasksEnvironment}[\oarg{options}\marg{name}\oarg{separator}\darg{cols}]
    Define environment \meta{name} that uses \meta{separator} to introduce a
    new item.  Default for \meta{separator} is \cs{task}, default for
    \meta{cols} is \code{1}.  The \meta{options} are the ones described in
    section~\ref{sec:tasks:options}.
  \command{RenewTasksEnvironment}[\oarg{options}\marg{name}\oarg{separator}\darg{cols}]
    Renew environment previously defined with \cs{NewTasksEnvironment}.
\end{commands}
The \env{tasks} environment is defined as follows:
\begin{sourcecode}
  \NewTasksEnvironment{tasks}
\end{sourcecode}

The separator does not have to be a control sequence:
\begin{example}
  % preamble:
  % \usepackage{fontawesome}
  \NewTasksEnvironment[label=\faThumbsOUp,label-width=15pt]{done}[*]
  \begin{done}
    * First task
    * Second task
  \end{done}
\end{example}
Although this might seem handy or even nice I strongly advice against using
something different than a command sequence. Remember that the items will be
split at \emph{every} occurrence of the separator.  So in order to use the
separator (here for example for a starred variant of a command) within an item
it has to be hidden in braces.  This is avoided of you use a command sequence
which even doesn't have to be defined.

Please also keep in mind that the separator still has an optional star
argument (see~\pageref{optional-star}), an optional bang argument and the
standard optional argument.  Using \code{*} will prevent the optional star
argument.

\begin{example}
  % preamble:
  % \usepackage{fontawesome}
  \NewTasksEnvironment[label=\faThumbsOUp,label-width=15pt]{done}[*]
  \begin{done}(3)
    * First task
    * Second task
    *! Third task spanning the full width available
    * Fourth task
  \end{done}
\end{example}

\section{Styling \Tasks}
\Tasks\ uses \pkg{xtemplate} to declare additional instances for the lists.

\subsection{The \code{tasks} Object}\label{sec:tasks}
The object that's defined by \Tasks\ is the `tasks' object.  This time there
are four instances available for the one template (again `default') that was
defined.

\subsubsection{Available Options}
This section only lists the options that can be used when defining an instance
of the `default' template.  The following subsections will give some examples
of their usage.

\begin{sourcecode}
  \DeclareTemplateInterface{tasks}{default}{3}
    {
      % option        : type      = default
      label           : tokenlist = \alph*) ,
      indent          : length    = 2.5em   ,
      label-format    : tokenlist           ,
      label-width     : length    = 1em     ,
      label-offset    : length    = .3333em ,
      after-item-skip : skip      = 1ex plus 1ex minus 1ex
    }
\end{sourcecode}

\subsubsection{Predefined Instances}
This is rather brief this time:
\begin{sourcecode}
  % alphabetize: a) b) c)
  \DeclareInstance{tasks}{alphabetize}{default}{}
  % itemize
  \DeclareInstance {tasks} {itemize} {default}
    {
      label-width  = 1.125em ,
      label        = \labelitemi
    }
  % enumerate:
  \DeclareInstance {tasks} {enumerate} {default}
    { label = \arabic*. }
\end{sourcecode}

\clearpage
\printbibliography

\end{document}