pstricks and calc (A2)

[Denis Girou]

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>>>>> "Werenfried.Spit" == Werenfried Spit <w.spit at witbo.nl> writes:

    Werenfried.Spit> This is precisely one of the things I find so valuable about pstricks. 
    Werenfried.Spit> Maybe it is wanting a bit too much to try to combine this power with 
    Werenfried.Spit> the ease of directly inputting simple arithmetics. Things like
    Werenfried.Spit>  \setcounter{left}{-10}
    Werenfried.Spit>  \setcounter{right}{10}
    Werenfried.Spit>  \setcounter{xa}{10}
    Werenfried.Spit>  \setcounter{xb}{50}
    Werenfried.Spit>  \setcounter{x}{\c at xa}\addtocounter{x}{\c at left}\rput(\c at x,0){a left}
    Werenfried.Spit>  \setcounter{x}{\c at xa}\addtocounter{x}{\c at right}\rput(\c at x,0){a right}
    Werenfried.Spit>  \setcounter{x}{\c at xb}\addtocounter{x}{\c at left}\rput(\c at x,0){b left}
    Werenfried.Spit>  \setcounter{x}{\c at xb}\addtocounter{x}{\c at right}\rput(\c at x,0){b right}
    Werenfried.Spit> do the job well. I was `only' looking for a way to make the input a bit
    Werenfried.Spit> less clumsy, maybe the way calc does.

  If you want to use counters rather than dimension registers, we must do
otherwise that I did yesterday (anyway, there was a serious bug in it that
I see tonigh, and coordinates like 12 or 2.3 did work any more... So, just
forget this solution.

  Here is a better one (I hope...). It manage transparentely counters and
dimensions. Nevertheless there are some pitfalls when using length variables.
And I don't test it a lot too...

D.G.

\documentclass{article}

\usepackage{calc}
\usepackage{pstricks}
\usepackage{pst-plot}

\makeatletter

% Interface between `calc' and PSTricks.
% We redefine the \pssetlength, \pssetxlength, \pssetylength and
% \psaddtolength macros to use \setlength if we detect that the coordinate
% is a formula (a formula is a string which contain an operation using
% "+", "-", "*" or "/".
% One value can contain integers only or dimensions only (real numbers follow
% by the ``pt'' string, as it must be TeX dimensions), but you can't mix
% integers and real values.

% Take care that there are pitfalls when using length variables.
%   - don't forget that the "string" pt must appear in there is a computation,
%     so add "+ 0pt" if needed
%   - if you use length variables, you must set locally "xunit=1pt" before
%     because in this case the unit will not be correct
%   - some complicated computations with length variables seems to doesn't work

% Take care also that it is a LaTeX solution only and that it obviously
% doesn't work in plain.

% Not heavily tested, take care!

% D.G. - August 7, 1998

\ifx\setlength\@undefined
% We are in plain, so we keep original versions and do nothing
\else
% We are in LaTeX
\newif\ifPst at Boolean
\newcounter{Pst at CounterA}

\def\pssetlength#1#2{%
\Pst at ComputeLength{#2}{\@tempa}%
\let\@psunit\psunit
\afterassignment\pstunit at off
#1 \@tempa\@psunit}

\def\psaddtolength#1#2{%
\Pst at ComputeLength{#2}{\@tempa}%
\let\@psunit\psunit
\afterassignment\pstunit at off
\advance#1 \@tempa\@psunit}

\def\pssetxlength#1#2{%
\Pst at ComputeLength{#2}{\@tempa}%
\let\@psunit\psxunit
\afterassignment\pstunit at off
#1 \@tempa\@psunit}

\def\pssetylength#1#2{%
\Pst at ComputeLength{#2}{\@tempa}%
\let\@psunit\psyunit
\afterassignment\pstunit at off
#1 \@tempa\@psunit}
\fi                             % End LaTeX test

% Return in #2 the length to use, allowing `calc' doing his job
% if #1 is a formula containing integers or real values (lengths)
\def\Pst at ComputeLength#1#2{%
\Pst at IsFormula{#1}%
\ifPst at Boolean
  % Formula detected: let `calc' do his job...
  % Do formula use integer values (counters) or real values (lengths)?
  \Pst at IsContainDimensions{#1}%
  \ifPst at Boolean
    % Lengths (dimensions)
    \setlength\pst at dima{#1}%
    \pst at dimtonum\pst at dima{#2}%
  \else
    % Counters
    \setcounter{Pst at CounterA}{#1}%
    \edef#2{\value{Pst at CounterA}}%
  \fi
\else
  % No formula: "normal" way
  \edef#2{#1}%
\fi}

\def\Pst at IsFormula#1{%
\Pst at Booleanfalse
\Pst at IsFormula@i#1+\@nil}

\def\Pst at IsFormula@i#1+#2\@nil{%
\edef\@tempa{#2}%
\ifx\@tempa\@empty
  \Pst at IsFormula@ii#1-\@nil%
\else
  % Formula: contain a "+"
  \Pst at Booleantrue
\fi}

\def\Pst at IsFormula@ii#1-#2\@nil{%
\edef\@tempa{#2}%
\ifx\@tempa\@empty
  \Pst at IsFormula@iii#1*\@nil%
\else
  % Formula: contain a "-"
  \Pst at Booleantrue
\fi}

\def\Pst at IsFormula@iii#1*#2\@nil{%
\edef\@tempa{#2}%
\ifx\@tempa\@empty
  \Pst at IsFormula@iv#1/\@nil%
\else
  % Formula: contain a "*"
  \Pst at Booleantrue
\fi}

\def\Pst at IsFormula@iv#1/#2\@nil{%
\edef\@tempa{#2}%
\ifx\@tempa\@empty
  % No "+", "-", "*" or "/": not a formula
\else
  % Formula: contain a "/"
  \Pst at Booleantrue
\fi}

\def\Pst at IsContainDimensions#1{%
\Pst at Booleanfalse
\Pst at IsContainDimensions@i#1pt\@nil}

\def\Pst at IsContainDimensions@i#1pt#2\@nil{%
\edef\@tempa{#2}%
\ifx\@tempa\@empty
\else
  % The argument contains the "pt" string, so we suppose that is contains
  % dimension values
  \Pst at Booleantrue
\fi}

\makeatother

\pagestyle{empty}

\Huge

\begin{document}

\newcommand{\LeftShift}{-1}
\newcommand{\RightShift}{1}

\newlength{\MyLengthA}
\newlength{\MyLengthB}

\setlength{\MyLengthA}{7.3cm}
\setlength{\MyLengthB}{1.7cm}

\begin{pspicture}(5,5)\psgrid[subgriddiv=0]
  \rput(1+\LeftShift,0){left}
  \rput(1+\RightShift,0){right}
  \rput(1+\LeftShift,1){once more}
  \rput(1+\RightShift,1){and again}
  %
  \rput(1,3.4){\pscirclebox{A}}
  %
  \rput(1,1 + 1){\pscirclebox{B}}
  % (3.44,4.56)
  \rput(2.1pt + 4.3pt / \real{3.2},1.2pt + 1.6pt * \real{2.1}){\pscirclebox{C}}
  \rput(6.3pt - 4pt,3 - \LeftShift){\pscirclebox{D}} % (2.3,4)
  \begingroup
   \psset{xunit=1pt} % Required as we will use length variables
   % (3.58,2)
   \rput(\textheight - \textwidth * \real{1.3} + 0pt,2){\pscirclebox{E}}
   \rput(\MyLengthA - \MyLengthB * \real{2} + 0pt,1){\pscirclebox{F}} % (3.9,1)
  \endgroup
\end{pspicture}

\vspace{1cm}

\newcommand{\Left}{-10}
\newcommand{\Right}{10}

\newcounter{xa}
\newcounter{xb}
\setcounter{xa}{10}
\setcounter{xb}{50}

\psset{unit=0.1}

\begin{pspicture}(80,10)
 \psaxes[Dx=10](80,0)
 \rput(\value{xa} + \Left,0){a left}
 \rput(\value{xa} + \Right,0){a right}
 \rput(\value{xb} + \Left,0){b left}
 \rput(\value{xb} + \Right,0){b right}
\end{pspicture}

\end{document}


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