improper sizes with pixel unit in MPinitialisation

improper sizes with pixel unit in MPinitialisation

[Peter Rolf]

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Hi,

I started using 'MPinitialisation' to store some global variables. Much
easier than passing them over and over again to MP macros. Sadly this
way is inaccurate with the unit 'px' (no such problems with 'pt').
See attached example. The frame gives the exact size, showing that the
MP graphic is 'out of bounds'.

MTXrun | current version: 2010.10.22 16:46
same result for both marks


Peter



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\setuppagenumber[state=stop]

\pdfpxdimen49336sp

\startMPinitializations
    px:= .7528125;
    fooWidth  := 600px;
    fooHeight := 400px;
\stopMPinitializations

\startuniqueMPgraphic{foo}
    fill unitsquare xyscaled(fooWidth,fooHeight) withcolor transparent(1,0.2,blue);
\stopuniqueMPgraphic

\starttext
\framed[offset=overlay,width=600px,height=400px,framecolor=darkblue]{\uniqueMPgraphic{foo}}
\stoptext

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Re: improper sizes with pixel unit in MPinitialisation

[Taco Hoekwater]

On 10/28/2010 12:12 PM, Peter Rolf wrote:
> Hi,
>
> I started using 'MPinitialisation' to store some global variables. Much
> easier than passing them over and over again to MP macros. Sadly this
> way is inaccurate with the unit 'px' (no such problems with 'pt').
> See attached example. The frame gives the exact size, showing that the
> MP graphic is 'out of bounds'.

Probably because metapost calculates in printer points of 72pt/in,
instead of tex's 72.27pt/in. So your mp scale factor is likely to
be a little off.

Best wishes,
Taco
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