Re: Re: externalfigure

[Vit Zyka <vit.zyka@seznam.cz>]

>>So I thing the case should work as expected. Could you send
>>complete-and-minimal example?
> 
> 
> \starttext
> \startMPcode
> externalfigure "hacker.jpg" scaled 300;
> \stopMPcode
> \stoptext

It seems to me the behaviour is perhaps not intuitive but correct. I try 
to explain:

Imagine externalfigure without scaling:
   externalfigure "hacker.jpg";
What we will obtain? One can imagine the image in its natural size. That 
  is not the case. We obtain the image of the size 1pt x 1pt. I thing 
there are two reasons for that:
1) Analogy. Imagine this example:
      draw origin--(1,0)--(1,1)--(0,1)--cycle;
    it is exactly the same as
      draw origin--(1pt,0)--(1pt,1pt)--(0,1pt)--cycle;
    and it is abbreviated to
      draw unitsquare;
    and im most cases it is used with scaling
      draw unitsquare xscaled 2cm yscaled 1cm;
    since
      scaled X = xscaled X yscaled X
    then
      unitsquare scaled 2cm
    is still square.

    If you do not specify the unit, the pt is deduced.
    So there is an analogy:
      "unitfigure" 1pt x 1pt = externalfigure "file"

2) Technician. The scaling dimensions are calculated by TeX engine.
    It is done by tricks in pt units, so image 1pt x 1pt simplifies
    the calculations.

If you want to use a bitmap in ConTeXt MP environment in its natural 
size, I suggest to precalculate (according to Hans macro \MPfigure) its 
dimmensions:

% ------------------------------------
\def\getMPfiguresize#1{%
    \getfiguredimensionsonly[#1]%
    \freezedimenmacro\naturalfigurewidth
    \freezedimenmacro\naturalfigureheight
}
\def\naturalMPfigure#1{%
   externalfigure "#1"
     xscaled \naturalfigurewidth\space
     yscaled \naturalfigureheight\space
}
\starttext
\getMPfiguresize{hacker.jpg}
\startMPcode
   \naturalMPfigure{hacker.jpg} ; % space in front of ; is important!!
\stopMPcode
\startMPcode
   \naturalMPfigure{hacker.jpg} scaled 2 slanted .3;
\stopMPcode
\stoptext
%-------------------------

Vit Zyka

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