MetaFun - Pragma ADE

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p := fullcircle scaled (2*length(loc-ori)) shifted ori ;
q := freesquare xyscaled (urcorner s - llcorner s) ;
l := point (xpart (p intersectiontimes (ori--loc))) of q ;
draw q shifted loc withpen pencircle scaled .5pt ;
draw l shifted loc withcolor .625yellow ;
draw loc withcolor .625red ;
s
enddef ;
The macro xyscaled is part of METAFUN and scales in two directions at once. The METAPOST primitive
intersectiontimes returns a pair of time values of the point where two paths intersect. The
first part of the pair concerns the first path.
text text text
text text
text
text
text
text
text
text
textextext text
text
We are now a small step from the exact placement. If we change the last line of the macro into:
(s shifted -l)
we get the displacement we want. Although the final look and feel is also determined by the text
itself, the average result is quite acceptable.
text text text
text
text
text
text
text
text
text
text
text texttext text text
Because we also want to pass pictures, and add a bit of offset too, the final implementation is
slightly more complicated. The picture is handled with an additional condition, and the offset
with the METAFUN macro enlarged.
newinternal freelabeloffset ; freelabeloffset := 3pt ;
vardef thefreelabel (expr str, loc, ori) =
save s, p, q, l ; picture s ; path p, q ; pair l ;
interim labeloffset := freelabeloffset ;
s := if string str : thelabel(str,loc)
else : str shifted -center str shifted loc fi ;
setbounds s to boundingbox s enlarged freelabeloffset ;
A few applications Free labels