Re: Bug: \textext inside \*MPinclusions causes error

[Hans Hagen <pragma@wxs.nl>]

On 1/21/2017 10:13 PM, Sergey Slyusarev wrote:
 >
 > see below

It's a single tex run so you can do:

\starttext

\newbox\MyMpBox \setbox\MyMpBox\hbox{foo}

\startMPcode
     draw textext("\copy\MyMpBox") ;
\stopMPcode

\startMPcode
     draw textext("\copy\MyMpBox") rotated 45;
\stopMPcode

\stoptext

> On Tue, Jan 17, 2017 at 11:35 AM, Hans Hagen <pragma@wxs.nl
> <mailto:pragma@wxs.nl>> wrote:
>
>     On 1/16/2017 8:31 PM, Sergey Slyusarev wrote:
>
>             the (subtle) difference between the two [*MPinclusions and
>             */MPinitializations/] is not a bug but a feature
>
>
>         If I understood correctly, *MPinitializations affects everything
>         and can't be assigned to a specific instance (or can it?),
>         in some cases (like mine) this difference is not so subtle.
>
>         Look at the following example (not so minimal):
>
>         \startMPinitializations
>
>         picture p;
>
>         p := image(
>
>         draw fullsquare scaled 1cm;
>
>         draw textext("1");
>
>         );
>
>         \stopMPinitializations
>
>         \startMPinitializations
>
>         picture s;
>
>         s := image(
>
>         draw (fullsquare rotated 45) scaled 1cm;
>
>         draw textext("2");
>
>         );
>
>         \stopMPinitializations
>
>         \defineMPinstance[foo][initializations=yes]
>
>         \startMPcode{foo}
>
>         picture q;
>
>         q := image(
>
>         draw fullcircle scaled 1cm;
>
>         draw textext("3");
>
>         );
>
>         draw q;
>
>         \stopMPcode
>
>         \startMPcode{foo}
>
>         draw p;
>
>         draw q shifted (2cm, 0);
>
>         draw s shifted (4cm, 0);
>
>         \stopMPcode
>
>         \defineMPinstance[bar][initializations=yes]
>
>         \startMPcode{bar}
>
>         picture r;
>
>         r := image(
>
>         draw fullcircle scaled 1cm;
>
>         draw textext("4");
>
>         );
>
>         draw r;
>
>         \stopMPcode
>
>         \startMPcode{bar}
>
>         draw p;
>
>         draw r shifted (2cm, 0);
>
>         draw s shifted (4cm, 0);
>
>         \stopMPcode
>
>
>         First, it shows why *MPinitializations can't replace
>         *MPinclusions for
>         me (it affects all instances),
>
>         and second, it silently produces produces some really unexpected
>         results:
>
>         It looks like it should produce (by line)
>
>         A circle with "3" inside (yes)
>
>         A square with "1" inside (yes); A circle with "3" inside again (no,
>         instead it produces circle with "2" inside); A rhombus with "2"
>         inside
>         (no, instead it produces a rhombus with "1")
>
>         and so on.
>
>         (tested on http://live.contextgarden.net/)
>
>         In fact, I failed to declare picture variable inside with text
>         inside
>         one *MPcode environment and pass it to another safely
>
>         (text either disappears or changes to other text, and this time
>         ConTeXt
>         returns no error), that surely is a bug?
>
>
>     no, it's the way it works ... but keep in mind that textexts are
>     something bound to a specific code snippet so you can bets do
>     something like this:
>
>     \starttext
>
>     \defineMPinstance[foo][definitions=yes]
>     \defineMPinstance[bar][definitions=yes]
>
>     \startMPdefinitions{foo}
>         vardef p =
>             image(
>                 draw fullsquare scaled 1cm;
>                 draw textext("1");
>             )
>         enddef ;
>     \stopMPdefinitions
>
>     \startMPdefinitions{bar}
>         vardef p =
>             image(
>                 draw (fullsquare rotated 45) scaled 1cm;
>                 draw textext("2");
>             )
>         enddef;
>     \stopMPdefinitions
>
>     \startMPcode{foo}
>         draw p;
>         draw image(
>             draw fullcircle scaled 1cm;
>             draw textext("3");
>         );
>         draw p;
>     \stopMPcode
>
>     \startMPcode{bar}
>         draw p;
>         draw image(
>             draw fullcircle scaled 1cm;
>             draw textext("4");
>         );
>     \stopMPcode
>
>     \stoptext
>
>
>
>     -----------------------------------------------------------------
>                                               Hans Hagen | PRAGMA ADE
>                   Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
>            tel: 038 477 53 69 | www.pragma-ade.nl
>     <http://www.pragma-ade.nl> | www.pragma-pod.nl
>     <http://www.pragma-pod.nl>
>     -----------------------------------------------------------------
>
>
> Thank you, Hans!
> I thought of this solution too (
> http://tex.stackexchange.com/questions/347908/metapost-text-labels-inside-mpinclusions/348066#348066
> <http://tex.stackexchange.com/questions/347908/metapost-text-labels-inside-mpinclusions/348066#348066>
> ), but in my particular case it didn't work, because the code inside
> vardef is only executed when macro is called (while image(...) is
> processed immediately). It would help if the macro could be called
> within *MPdefinitions, like this:
>
> \starttext
> \startMPdefinitions
> picture tmp;
> vardef p =
> image(
> draw fullcircle scaled 5cm;
> draw textext("test");
> )
> enddef;
> tmp := image(draw p;);
> \stopMPdefinitions
> \startMPcode
> draw p;
> \stopMPcode
> \stoptext
>
> but that predictably generates the same error ("! Equation cannot be
> performed (color=vacuous).").
>
> Anyway, I solved my problem somehow (by running the code inside
> *reusableMPgraphic and reusing it for the first time inside \setbox that
> is never shown
> https://github.com/jemmybutton/byrne-euclid/commit/8c05cc96405f0ee33e6901a7fa66b2dffcda45ad#diff-6a58985423a46a2bb439cfdf26904e5fL30
> , at the cost of being unable to modify the image).
> Now I see that the fact that it's almost impossible to use images with
> text inside, outside of their environment of origin is not a bug, but a
> natural limitation of the system, and the first message should have been
> not about "bug", but more about something like "feature request". Sorry
> for being hasty.
>
> Sergey.


-- 

-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
        tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
-----------------------------------------------------------------
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