# Clipping with PSTricks

Consider the following example.

Code

\documentclass{article}

\begin{document}

\begin{figure}
\psset{unit=0.05}
\begin{pspicture}(120,216)
\pnodes{P}(0,0)(0,120)(186,120)(216,120)(216,0)(186,0)(186,30)(186,90)
\pspolygon(P0)(P1)(P3)(P4)
\pcline[offset=12pt]{|<->|}(P1)(P3)
\ncput*[nrot=:U]{216}
\pcline[offset=12pt]{|<->|}(P3)(P4)
\ncput*[nrot=:U]{120}
\pspolygon[linestyle=none,fillstyle=vlines](P2)(P3)(P4)(P5)
\pswedge[linestyle=none,fillstyle=solid,fillcolor=white](P6){30}{270}{90}
\pswedge[linestyle=none,fillstyle=solid,fillcolor=white](P7){30}{270}{90}
\psarc(P6){30}{270}{90}
\psarc(P7){30}{270}{90}
\psdot(P6)
\psdot(P7)
\end{pspicture}
\end{figure}

\end{document}


Output

Question

The code above seems to be the wrong way of creating the figure. I guess \pscustom is the way to go, but I cannot figure out how to use it; how do I produce the figure in the "best" way using PSTricks? (I would very much like to see how it is done and not just get a comment about using this or that.)

-

Two frames and two arcs or \pscustom:

\documentclass{article}
\begin{document}

\psset{unit=1pt}
\begin{pspicture}(240,140)
\psframe[dimen=middle](216,120)
\psframe[fillstyle=vlines,linestyle=none](186,0)(216,120)
\psarc[fillstyle=solid,fillcolor=white](186,30){30}{-90}{90}
\psarc[fillstyle=solid,fillcolor=white](186,90){30}{-90}{90}
\psdots(186,30)(186,90)
\pcline[offset=12pt]{|<->|}(0,120)(216,120) \ncput*{216}
\pcline[offset=12pt]{|<->|}(216,120)(216,0) \ncput*[nrot=:U]{120}
\end{pspicture}

\begin{pspicture}(240,140)
\psframe[dimen=middle](216,120)
\pscustom[fillstyle=vlines,hatchcolor=red]{%
\psarc(186,30){30}{-90}{90}
\psarc(186,90){30}{-90}{90}
\psline(186,120)(216,120)(216,0)
}
\psdots(186,30)(186,90)
\pcline[offset=12pt]{|<->|}(0,120)(216,120) \ncput*{216}
\pcline[offset=12pt]{|<->|}(216,120)(216,0) \ncput*[nrot=:U]{120}
\end{pspicture}

\end{document}


Since \psframe draws a closed path (required for proper clipping), it can also be added as the last component in \pscustom if one uses the clipping function:

\documentclass{article}
\begin{document}

\begin{figure}
\psset{unit=1pt}
\begin{pspicture}(240,140)
\psclip{\psset{linestyle=solid}
\pscustom{
\psarc(186,30){30}{-90}{90}
\psarc(186,90){30}{-90}{90}
\psframe[dimen=middle](216,120)
}
}
\psframe[fillstyle=vlines,linestyle=none](186,0)(216,120)
\endpsclip
\psdots(186,30)(186,90)
\pcline[offset=12pt]{|<->|}(0,120)(216,120) \ncput*{216}% Top dimension
\pcline[offset=12pt]{|<->|}(216,120)(216,0) \ncput*[nrot=:U]{120}% Right dimension
\end{pspicture}
\end{figure}

\end{document}


This also works because of the structure and the way \psframe is drawn (counter-clockwise from middle-left.

-
Thank you, Herbert! (Any chance I can make you show how to use \pscustom?) –  Svend Tveskæg Apr 3 '13 at 16:49
@SvendMortensen: See my edited answer. –  Herbert Apr 3 '13 at 19:30
@Herbert Nice! Do you recommend one of the ideas over the other? –  Svend Tveskæg Apr 3 '13 at 19:37
@SvendMortensen: that depends ... ;-) if I have enough time then I'd use \pscustom ... –  Herbert Apr 3 '13 at 19:42
Okay. Thank you! –  Svend Tveskæg Apr 3 '13 at 19:43

I am trying to improve the existing answers.

• Arrow specifier |<->| should be changed to |<*->|* to make the |-like tips properly aligned.
• It is better to globally pass dimen=middle to \pscustom rather than locally specifying it to every single command which has dimen=outer by default.
• As the clipped region is drawn after stroking the clipper path, in general it is necessary to stroke again the clipper path after clipping.

If you want to understand what I mean, I have added hatchcolor=red,hatchsep=1pt to the clipped \psframe in Werner's edit. Originally Werner's setting is hatchcolor=black so it is unnoticeable but now with the color change, the "defect" is visually obvious as follows.

That is why restroking is needed after clipping.

• Using unit=1pt should be avoided because the navigation grid becomes messy.

\documentclass[pstricks,border=12pt]{standalone}
\usepackage{pst-node}
\def\Path[#1]{%
\pscustom[dimen=middle,#1]{
\psarc(186,30){30}{-90}{90}
\psarc(186,90){30}{-90}{90}
\psframe(216,120)
}\ignorespaces
}

\begin{document}

\psset{unit=1pt,linewidth=3pt}
\begin{pspicture}(240,140)
\psclip{\Path[linestyle=none]}
\psframe[fillstyle=vlines,hatchcolor=red,hatchsep=1pt,linestyle=none](186,0)(216,120)
\endpsclip
\Path[]
\psdots(186,30)(186,90)
\pcline[offset=12pt]{|<*->|*}(0,120)(216,120) \ncput*{216}% Top dimension
\pcline[offset=12pt]{|<*->|*}(216,120)(216,0) \ncput*[nrot=:U]{120}% Right dimension
\end{pspicture}

\end{document}

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Very nice! I will take a look at this and maybe/probably use this version! (I will ping @Herbert to let him know; he might be interested.) –  Svend Tveskæg Apr 6 '13 at 15:12