drawoptions in \startMPinclusions

drawoptions in \startMPinclusions

[nicola]

Hi,
the following code

\startMPinclusions
drawoptions(withpen pencircle scaled 1mm);
u := 1cm;
\stopMPinclusions

\startreusableMPgraphic{foo}
draw origin--(u,u);
\stopreusableMPgraphic

\starttext
\midaligned{\reuseMPgraphic{foo}}
\stoptext

produces a line with default thickness, not 1mm wide. Is this a bug? Or 
do I misunderstand the purpose of \startMPinclusions (I have assumed 
that it inserts the text verbatim inside each figure definition)? I am 
using

ConTeXt  ver: 2007.01.12 15:56 MKII  fmt: 2007.6.8  int: english/english

Nicola

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Re: drawoptions in startMPinclusions

[Aditya Mahajan]

Quoting nicola <vitacolo@dimi.uniud.it>:

> Hi,
> the following code
>
> \startMPinclusions
> drawoptions(withpen pencircle scaled 1mm);
> u := 1cm;
> \stopMPinclusions
>
> \startreusableMPgraphic{foo}
> draw origin--(u,u);
> \stopreusableMPgraphic
>
> \starttext
> \midaligned{\reuseMPgraphic{foo}}
> \stoptext
>
> produces a line with default thickness, not 1mm wide. Is this a bug?

No a feature of metapost. beginfig resets drawoptions. Otherwise 
drawoptions from one figure will also affect the output of another 
figure.

> Or > do I misunderstand the purpose of \startMPinclusions (I have assumed
> that it inserts the text verbatim inside each figure definition)?

It inserts text *before* the figure definitions. Have a look at the 
resulting -mpgraph.mp file. The problem is that in metapost beginfig 
resets drawoptions. This is how beginfig is defined

def beginfig(expr c) =
  begingroup
  charcode:=c;
  clearxy; clearit; clearpen;
  pickup defaultpen;
  drawoptions();
  scantokens extra_beginfig;
enddef;

So, you can use
\startMPinclusions
extra_beginfig := "drawoptions(withpen pencircle scaled 1mm)" ;
u := 1cm;
\stopMPinclusions

to override beginfig's redefinitions. I hope that some day there will 
be a overhaul of plain.mp to something more flexible. Metafun provides 
some useful enhancements, but the metapost user interface is still very 
low level.

Aditya
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maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
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archive  : https://foundry.supelec.fr/projects/contextrev/
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