Re: Metafun: is it possible to redefine dotlabel to draw a square ?

[Hans Hagen <j.hagen@xs4all.nl>]

On 12/10/2020 6:44 PM, Aditya Mahajan wrote:
> On Thu, 10 Dec 2020, Otared Kavian wrote:
> 
>> Hi all,
>>
>> In Metafun when representing a point I woul dlike to have some dots represented by a square (or even by another scalable symbol): for instance in the following I would like the dot at the point B to be a square:
>>
>> \starttext
>> \startMPcode
>> draw (2cm,3cm) -- (3cm,5cm) ;
>> dotlabel(textext("\switchtobodyfont[8pt]" & "A"), (2cm,3cm))
>> 	withpen pencircle scaled 12pt
>> 	withcolor transparent("exclusion",.5,red) ;
>>
>> dotlabel(textext("\switchtobodyfont[8pt]" & "B"), (3cm,5cm))
>> 	withpen pencircle scaled 12pt
>> 	withcolor transparent("exclusion",.5,red) ;
>> \stopMPcode
>> \stoptext
>>
>> I wonder whether it is possible to define something like « drawsquaredot » or « squaredotlabel » in order to do this.
> 
> dotlabel uses a pen to draw the dot, and I am not sure why it uses that rather than a path. Here is a (to me) simpler definition, where you can change the shape:

just look in the pdf ... in your case the dot is a n point path while 
otherwise it uses the default postscript pen (which is a dot)

actually fullcircle is pencircle so you can ponder why that is the case -)

> \startMPdefinitions
> newpath dotlabelshape;
> 
> dotlabelshape := fullcircle;
> 
> vardef dotlabel@#(expr s,z) text t_ =
>      label@#(s,z) t_ ;
>      fill (dotlabelshape scaled 2dotlabeldiam) shifted z t_;
> enddef ;
> \stopMPdefinitions
> 
> \starttext
> \startMPcode
> newpath p ;
> p := (2cm, 3cm) -- (3cm, 5cm);
> dotlabeldiam := 12pt;
> 
> % Default
> draw p;
> dotlabel(textext("\switchtobodyfont[8pt]" & "A"), point 0 of p)
>          withcolor transparent("exclusion",.5,red) ;
> 
> dotlabel(textext("\switchtobodyfont[8pt]" & "B"), point 1 of p)
>          withcolor transparent("exclusion",.5,red) ;
> 
> % Using a square "dot"
> p := p shifted (5cm, 0);
> dotlabelshape := fullsquare;
> 
> draw p;
> dotlabel(textext("\switchtobodyfont[8pt]" & "A"), point 0 of p)
>          withcolor transparent("exclusion",.5,red) ;
> 
> dotlabel(textext("\switchtobodyfont[8pt]" & "B"), point 1 of p)
>          withcolor transparent("exclusion",.5,red) ;
> \stopMPcode
> \stoptext
> 
> These types of macros are also a good candidate for the new LMTX syntax, where we can make all components configurable via a key-value interface (labeldistance etc. as well).
it surprised me that a math guru like you doesn't do this:

vardef dotlabel@#(expr s,z) text t_ =
%     draw textext("$\bullet$") scaled (1/2) shifted z ;
%     draw textext("$\blacktriangle$") scaled (1/4) shifted z ;
     draw textext("$\blacksquare$") scaled (1/4) shifted z ;
     label@#(s,z) t_ ;
enddef ;
\stopMPdefinitions



-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
        tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
-----------------------------------------------------------------
___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://context.aanhet.net
archive  : https://bitbucket.org/phg/context-mirror/commits/
wiki     : http://contextgarden.net
___________________________________________________________________________________