On = 3 May 2020, at 15:01, Gerben Wierda <gerben.wierda@rna.nl> wrote:

Am 01.05.2020 um 10:26 schrieb Gerben Wierda <gerben.wierda@rna.nl>:

I = have been looking at lmt_followtext and followtext to get typesetting = done along a path. That works fine, except that in my case, I need the = text to not be exactly on that path, I need it to hover slightly above = tor below he path. Given that the path may have an unpredictable form, = that means that all the glyphs need to be shifted a bit, there is no = generic transfrom of the entire text string that will work,

Can=E2=80=99t you duplicate and = shift the path, i.e. keep the original visible and make the copy that = carries the text invisible? That=E2=80=99s what I would do in a = graphical application, but I would be surprised if MP wouldn=E2=80=99t = know a transformation for this purpose.

No, that is what I did in the example, fiddling, but there is = no transformation that will work in all cases. E.g. on the left side of = the bump, I need to go to the upper left, on the right side to the upper = right. There is no single shift that helps me. Nor a scale rotation or = shift combination. That could be managed by only going up (though the = distance to the path would vary, on the sides the text would be very = close or on the top it would be too far.)

There is an example, at the link below, of creating a = parallel path that claims to cope with sharp bends in the original path. = You might be able to adapt it?
<https://therion.speleo.sk/wiki/metapost#shuttering_two_parallel= _lines>

That looks great. I=E2=80=99m going to = investigate.

That approach works fine. Example trial = code:

\starttext

\startMPpage
vardef parallelpath (expr P, gap)=3D
% = adapted from https://therion.speleo.sk/wiki/metapost#shuttering_two_parallel= _lines
save pathlength, linegap, testdiameter, = testpath, innerpath, newpoint, curlength, intersections, samplepoint, = sampledir, accuracy;
% work out a parallel path
% the easy way is to sample direction every few units, = and add a parallel point into a new path
% however, = this causes weird loops at sharp corners, so check if a sharp corner is = coming up within
% the length of the gap between = lines, and ignore that point if so
= pathlength:=3Darclength P;
linegap:=3Dgap;
accuracy:=3D2;
= testdiameter:=3Dlinegap;
path testpath;
testpath:=3D(halfcircle rotated 180) scaled = testdiameter;
pair newpoint;
= pair sampledir;
path innerpath;
= pair intersections;
curlength:=3D0;
forever:
= samplepoint:=3Darctime curlength of P;
= sampledir:=3Ddirection samplepoint of P;
= newpoint:=3D((point samplepoint of P) shifted (linegap * = unitvector(sampledir rotated -90)));
if = curlength =3D 0:
= innerpath:=3Dnewpoint{sampledir};
fi
% every now and then along the line, place a = semicircle, rotated to face away from the line, offset by the thickness = of the line,
% with a radius the same as the = gap between the lines - if its ends touch the main line's centre, the = corner is too sharp to use
% this point
save truetestpath; path truetestpath; = truetestpath :=3D (testpath rotated (angle sampledir) shifted (point = samplepoint of P));
intersections:=3DP = intersectiontimes truetestpath;
% if there = are no intersections, intersectiontimes returns (-1,-1), otherwise it = returns the distance along each path (P,testpath)
= % where the intersection happened >=3D0
= if (xpart intersections) =3D -1:
= show "ADDED", newpoint{sampledir};
= innerpath:=3Dinnerpath .. newpoint{sampledir};
= else:
show "REJECTED", = newpoint{sampledir};
draw = truetestpath withcolor green withtransparency (1,0.1);
fi;
exitif = curlength =3D pathlength;
% move in small = steps, to take account of tight backwards curves, and to get points near = a corner
curlength:=3Dcurlength + = testdiameter/accuracy;
if curlength > = pathlength:
curlength:=3Dpathlength; fi;
endfor;
if known innerpath:
if = cycle P:
innerpath:=3Dinnerpath .. = cycle;
fi;
fi;
innerpath
enddef;

path testIn, testOut;

testIn :=3D = (0,0)..(100,50)..(50,100)..(130,0);
testOut :=3D = parallelpath( testIn, 2);

draw testIn = withpen pencircle scaled 1;
%draw testOut withpen = pencircle scaled 1 withcolor red;
draw lmt_followtext [
text =3D "How well does it work? {\it It works very = well!} {\bf It looks good enough.}",
path =3D = reverse testOut,
spread =3D false,
];

Going to = work with it. Thanks again.