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%%
%% This is file `bckwrdexample.tex',
%% generated with the docstrip utility.
%%
%% The original source files were:
%%
%% texpower-doc.dtx (with options: `bckwrdexample,bckwrdexample-src,end')
%%
%% --------------------------------------------------------------
%% TeXPower bundle - dynamic online presentations with LaTeX
%% Copyright (C) 1999-2004 Stephan Lehmke
%% Copyright (C) 2003-2005 Hans Fredrik Nordhaug
%%
%% This program is free software; you can redistribute it and/or
%% modify it under the terms of the GNU General Public License
%% as published by the Free Software Foundation; either version 2
%% of the License, or (at your option) any later version.
%%
%% This program is distributed in the hope that it will be useful,
%% but WITHOUT ANY WARRANTY; without even the implied warranty of
%% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
%% GNU General Public License for more details.
%% --------------------------------------------------------------
%%
%% The list of all files belonging to the TeXPower bundle is
%% given in the file `00readme.txt'.
%%
\ProvidesFile{bckwrdexample.tex}%
[2005/04/07 TeXPower example file]
%-----------------------------------------------------------------------------------------------------------------
%
% Backwards writing example for the package texpower.sty.
%
%-----------------------------------------------------------------------------------------------------------------
% Set background color to black and use slifonts.
\PassOptionsToPackage{blackbackground}{texpower}
\RequirePackage{tpslifonts}
% Input the generic preamble.
\input{__TPpreamble}
\hypersetup{pdftitle={texpower backwards writing example}}
% Define \includegraphics for including an mps (metapost postscript) image.
\usepackage{graphicx}
% The mps extension isn't supported out-of-the-box for latex+dvips
\ifthenelse{\boolean{psspecialsallowed}}{%
\DeclareGraphicsExtensions{.mps}}{}
%-----------------------------------------------------------------------------------------------------------------
% Finally, everything is set up. Here we go...
%
\begin{document}
\begin{slide}
%-----------------------------------------------------------------------------------------------------------------
%
\makeslidetitle{\macroname{stepwise} Example: Writing Backwards}\label{Sec:ExBackwards}
%
% The following example doesn't really demonstrate a useful application. Its purpose is twofold:
% a) Show how the functionality of \stepwise can be extended by the user by referring to the macros provided by the
% package.
% b) Show that \steps can appear in any order, and can be made to appear simultaneously in several places (and mention
% the problems this raises).
% We define a new macro \backstep which will call \step, but the steps will be executed in _reverse_ order.
% This is achieved as follows:
% * We refer to the counter totalsteps, which gives the total number of steps occurring in this argument of
% \stepwise.
% * From this, we subtract the value of the counter stepcommand, which gives the number of this \step command (in the
% order of appearance).
% * The result is compared with the counter step, which gives the number of the current step.
% (the default for `triggering' a \step is the condition \value{step}=\value{stepcommand})
%
% Note that if the ifthen Package would support this syntax, we could use the bracketed optional argument of \step (as
% in the previous example), defining \backstep like this:
%
% \newcommand{\backstep}{\step[\value{totalsteps}-\value{stepcommand}+1=\value{step}]}
%
% As \ifthenelse doesn't offer this syntax, we have to calculate \value{totalsteps}-\value{stepcommand}+1 in a separate
% counter. This doesn't fit the intended use of \step's optional argument. But hey, there is another syntax ;-)
% If the optional argument is specified with braces (...), then it can contain an arbitrary test which takes two
% arguments and selects the first if it succeeds and the second if it fails. We use this variant here.
%
\newcounter{reversestepno}%
\newcommand{\backstep}{\step(\setcounter{reversestepno}{\value{totalsteps}-\value{stepcommand}+1}\ifthenelse{\value{step}=\value{reversestepno}})}%
%
% We use the custom command \parstepwise which not only wraps the whole argument of \stepwise into a minipage (because
% otherwise vertical spacing goes haywire, don't ask me why), but also gives substance to steps.
%
% If the following \stepwise command would only contain the calls to \backstep, everything would be fine.
% But we _had_ to add something else....
% In the second part of this application of \stepwise, several steps are executed simultaneously with those executed
% backwards in the first part. This means the value of the counter totalsteps is 14, i.e. the calls to \backstep
% correspond to steps 8...14. To remedy this, we decree that the first step performed shall be number 7, by setting
% the counter firststep accordingly in the optional argument of \stepwise.
%
\parstepwise[\setcounter{firststep}{\value{totalsteps}/2+\value{firststep}}]
{%
\begin{quote}
\Huge
\backstep{Is} \backstep{now} \backstep{it}
\backstep{backwards} \backstep{write} \backstep{to}
\backstep{possible\,!}
\bigskip
% By determining explicitly the times at which the following steps are executed, we make them appear
% simultaneously with the preceding flock of \backsteps. As we have set the counter firststep to 7, we start
% counting with 8.
%
\step[\value{step}=8]{\includegraphics[width=2cm]{fig-1}}
\step[\value{step}=9]{\includegraphics[width=2cm]{fig-1}}
\step[\value{step}=10]{\includegraphics[width=2cm]{fig-1}}
\step[\value{step}=11]{\includegraphics[width=2cm]{fig-1}}
\step[\value{step}=12]{\includegraphics[width=2cm]{fig-1}}
\step[\value{step}=13]{\includegraphics[width=2cm]{fig-1}}
\step[\value{step}=14]{\includegraphics[width=2cm]{fig-1}}%
\end{quote}
}%
\newslide
\end{slide}
\end{document}
\endinput
%%
%% End of file `bckwrdexample.tex'.
|
