PSTricks arrowheads

[Denis Girou]

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The following message is a courtesy copy of an article
that has been posted to comp.text.tex as well.

>>>>> "Torben.Hoffmann" == Torben Hoffmann <toho at it.dtu.dk> writes:

    Torben.Hoffmann> Hi there,
    Torben.Hoffmann> I would like to know how I can get arrowheads in PSTricks which are
    Torben.Hoffmann> _not_ filled  out as the default ones, ie, I want a triangle that is
    Torben.Hoffmann> white inside!

    Torben.Hoffmann> I have looked at the code in the 'pstricks.tex' file as well as finding
    Torben.Hoffmann> a message about how to make new arrowheads on the PSTricks mailing list,
    Torben.Hoffmann> but I cannot help thinging that someone has done this allready.

  This is not a functionality provided by PSTricks, which define only solid
arrows, but basically this is only a one line change (in the PostScript macro 
Arrow from pstricks.pro).

  Nevertheless there is a pitfall, because the current linewidth must be restored,
as it is temporary modified by a scaling mechanism during arrow drawing. It is 
also better to add a new parameter ("arrowfill" here) to choice between
filling or no filling, and to manage also double arrows (this require some
changes in their respective definitions).

  Here is a solution, but I do not test it extensively, so you must verify
that it has no side effect when using it in a more general context.

\documentclass[a4paper]{article}

\usepackage{pstricks}

% "arrowfill" parameter defined, to implement no filled arrows - D.G. (07/29/99)
\makeatletter

% Redefininition of \psset at arrowscale to store value of X scale factor
\def\psset at arrowscale#1{%
% D.G. modification begin - Jul. 29, 1999
\psset at arrowscale@i#1 \@nil
% D.G. modification end
\pst at getscale{#1}\psk at arrowscale}

\def\psset at arrowscale@i#1 #2\@nil{\edef\pst at arrowscale{#1}}

% Initialization of \pst at arrowscale with "arrowscale" default value (1)
\def\pst at arrowscale{1}

% New parameter "arrowfill", with default as "true"
\newif\ifpsarrowfill
\def\psset at arrowfill#1{\@nameuse{psarrowfill#1}}
\psset at arrowfill{true}

% Modification of the PostScript macro Arrow to choose to fill or not the arrow
% (it require to restore the current linewidth, despite of the scaling)
\pst at def{Arrow}<{%
CLW mul add dup 2 div
/w ED mul dup
/h ED mul
/a ED
{ 0 h T 1 -1 scale } if
% D.G. modification begin - Jul. 29, 1999
gsave
\ifpsarrowfill
\else
  \pst at number\pslinewidth \pst at arrowscale\space div SLW
\fi
% D.G. modification end
w neg h moveto
0 0 L w h L w neg a neg rlineto
% D.G. modification begin - Jul. 29, 1999
% gsave fill grestore
\ifpsarrowfill
  gsave fill grestore
\else
  gsave closepath stroke grestore
\fi
grestore
0 h a sub moveto
% D.G. modification end
}>

\@namedef{psas@>>}{%
false \psk at arrowinset \psk at arrowlength \psk at arrowsize \tx at Arrow
% D.G. modification begin - Jul. 30, 1999
% We suppress also the gap between the two arrows
% 0 h T
0 h a sub T
% D.G. modification end
gsave
newpath
false \psk at arrowinset \psk at arrowlength \psk at arrowsize \tx at Arrow
CP
grestore
% D.G. modification begin - Jul. 30, 1999
% CP newpath moveto 2 copy L stroke
% D.G. modification end
moveto
}

\@namedef{psas@<<}{%
true \psk at arrowinset \psk at arrowlength \psk at arrowsize \tx at Arrow
% D.G. modification begin - Jul. 30, 1999
% We suppress also the gap between the two arrows
% CP newpath moveto 0 a neg L stroke 0 h neg T
0 h neg a add T
% D.G. modification end
false \psk at arrowinset \psk at arrowlength \psk at arrowsize \tx at Arrow
% D.G. modification begin - Jul. 30, 1999
0 h a 5 mul 2 div sub moveto
% D.G. modification end
}

\makeatother

\pagestyle{empty}

\begin{document}

\psset{subgriddiv=0,arrowscale=3}

\begin{pspicture}(3,3)\psgrid
  \psline{->}(2,2)
  \parabola[linestyle=dotted,linecolor=red,arrowinset=0]{<->}(0.5,0)(1.5,3)
\end{pspicture}
\hfill
\psset{arrowfill=false}
\begin{pspicture}(3,3)\psgrid
  \psline{->}(2,2)
  \parabola[linestyle=dotted,linecolor=red,arrowinset=0]{<->}(0.5,0)(1.5,3)
\end{pspicture}
\hfill
\begin{pspicture}(3,3)\psgrid
  \psset{arrowsize=0.2}
  \psline{->}(2,2)
  \parabola[linecolor=red,arrowinset=0]{<->}(0.5,0)(1.5,3)
\end{pspicture}

\psset{arrowscale=6}

\vspace{2cm}
\begin{pspicture}(3,3)\psgrid
  \parabola[arrowfill=true]{>>->>}(0.5,0)(1.5,3)
\end{pspicture}
\hfill
\begin{pspicture}(3,3)\psgrid
  \parabola[arrowfill=false]{>>->>}(0.5,0)(1.5,3)
\end{pspicture}

\vspace{2cm}
\begin{pspicture}(3,3)\psgrid
  \parabola[arrowfill=true]{>|->|}(0.5,0)(1.5,3)
\end{pspicture}
\hfill
\begin{pspicture}(3,3)\psgrid
  \parabola[arrowfill=false]{>|->|}(0.5,0)(1.5,3)
\end{pspicture}

\end{document}


Denis Girou
-- 
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