In the interest of archiving the answer I ended up simply redefining the
p_label function:
# Overwrite the point label function to allow specifying
# style and label level
layout custom_label
code metapost
# Set the maximum label level that will appear
max_level := 100;
vardef set_label_level (expr mylevel)=
max_level := scantokens(mylevel);
enddef;
vardef p_label@#(expr txt,pos,rot,mode_)=
# Allow specifiying the style on a single label
if known ATTR_style:
mode := scantokens(ATTR_style);
else:
mode := mode_;
fi;
# Specify the level at which this label should appear
if known ATTR_level:
level := scantokens(ATTR_level);
else:
level := 0;
fi;
if (level <= max_level):
if (mode=1) or (mode=7):
interim labeloffset:=(u/8);
fi;
lab:=thelabel@#(txt, pos);
if mode>1:
pickup PenD
fi;
if mode=1:
pickup pencircle scaled (u/6);
drawdot(pos);
process_label(pos,0);
elseif mode=2:
process_uplabel;
elseif mode=3:
process_downlabel;
elseif mode=4:
process_updownlabel;
elseif mode=5:
process_circledlabel;
elseif mode=6:
process_boxedlabel;
elseif mode=7:
process_label(pos,rot); % station name
elseif mode=8:
process_filledlabel(pos, rot);
else:
process_label(pos,rot);
fi;
else:
# Metapost is expecting some sort of drawing so
# we just draw an empty string
lab:=thelabel@#("", pos);
process_label(pos,rot);
fi;
enddef;
endcode
endlayout
This has the levels functionality as well as displaying all text using the
correct fonts and characters.
On Sun, 17 Apr 2022 at 22:00, Rhys Tyers <rhystye...@gmail.com> wrote:
> Just in case a simplification makes the question/answer clearer, I'll
> retry my question from above:
>
> I define a user label:
>
> def p_u_label (expr P,R,S,A)=
> lab:=thelabel(ATTR_text, P)
> process_label(P, R)
> enddef;
> initsymbol("p_u_label");
>
> This for example will not print a Č character, but the standard Therion
> label will.
>
> How do I make this display text the same way that a normal Therion label
> does?
>
> I’ve read through a lot of the Therion source trying to find out where
> this happens but in the relevant bit
> <https://github.com/therion/therion/blob/master/mpost/thText.mp> there
> seems to be no extra magic happening.
>
> Thanks,
> Rhys
>
> On Wed, 13 Apr 2022 at 21:18, Rhys Tyers <rhystye...@gmail.com> wrote:
>
>> Hello again,
>>
>> I’m hoping someone can help me work out a metapost problem. The code is
>> available here
>> <https://github.com/iccaving/migovec-survey-data/blob/master/layouts/metapost/user_label.thl>
>> and pasted below.
>>
>> None of us know anything about metapost so this is a copy/paste job of
>> this <https://www.mail-archive.com/therion@speleo.sk/msg07234.html> code
>> with some extensions. We want a label that can be turned displayed or
>> hidden depending on a level variable. In a system survey I turn off lots of
>> labels because there is lots of overlapping passage, but on more detailed
>> ones I turn them back on. This level thing works well.
>>
>> What does not work is new lines or any non-ascii character. I have played
>> around with this for a while and can’t work out how to make it work.
>>
>> I.e. this point:
>>
>> point 174.2178 755.6161 u:label_MY -attr lvl 1 -attr text "Hoover<br>Dam"
>> -align tr -scale l
>>
>> The <br> is not replaced by a new line and in fact the < and > are
>> rendered as question marks.
>> [image: image.png]
>>
>>
>> I think Therion does a substitution of <br> and it’s not real html or
>> tex but if I try to use tex in there like Hoover \\ Dam then it just errors
>> during compilation:
>>
>> [495] (./mptextmp.mp) [496] [497] [498] (./mptextmp.mpfatal: Command failed:
>> etex --parse-first-line --interaction=nonstopmode mpTXLjoJ.tex; see
>> mpxerr.log
>> >> mptextmp.mp
>> >> mptextmp.mpx
>> ! ! Unable to read mpx file.
>> l.2 btex
>> \mainfont \thframed {\thnormalsize Hoover \\ Dam} etex
>>
>> I think this is because we are somehow not rendering with tex, and only
>> rendering with metapost which has a limited character set, but I really
>> have no idea.
>>
>> Any help would be greatly appreciated!
>>
>> The metapost code:
>>
>> layout user_label
>>
>> code metapost
>>
>> def p_LABEL(expr pos)=
>> T:=identity shifted pos;
>> pickup PenD;
>> p:=fullcircle scaled .1u;
>> thclean p; thdraw p;
>>
>> if known ATTR_text:
>> text := scantokens(ATTR_text);
>> thdrawoptions(withcolor .8red + .4blue);
>> txtm:=image(
>> draw txt;
>> interim labeloffset:=0;
>> label.urt(btex text etex);
>> );
>> % draw label
>> lab:=thelabel@#(txtm, pos);
>> draw lab _thop_; % use color
>> thdrawoptions();
>> bboxmargin:=0.8bp;
>> write_circ_bbox((bbox lab) smoothed 2);
>>
>> enddef;
>>
>> def p_altitude(expr pos)=
>> T:=identity shifted pos;
>> pickup PenD;
>> p:=(-.3u,0)--(.3u,0);
>> thdraw p; thdraw p rotated 90;
>> p:=fullcircle scaled .2u;
>> thclean p; thdraw p;
>> enddef;
>>
>>
>> vardef p_label@#(expr txt,pos,rot,mode) =
>> if mode=1:
>> thdrawoptions(withcolor .8red + .4blue);
>> p_altitude(pos);
>> % append "m" to label
>> picture txtm;
>> txtm:=image(
>> draw txt;
>> interim labeloffset:=0;
>> label.urt(btex \thaltitude m etex, lrcorner txt);
>> );
>> % give extra offset in case of l/r/t/b alignment
>> pair ctmp;
>> ctmp:=center thelabel@#("x", (0,0));
>> if (xpart ctmp * ypart ctmp)=0:
>> interim labeloffset:=(.4u);
>> else: % diagonal alignment
>> interim labeloffset:=(.2u);
>> fi;
>> % draw label
>> lab:=thelabel@#(txtm, pos);
>> draw lab _thop_; % use color
>> thdrawoptions();
>> bboxmargin:=0.8bp;
>> write_circ_bbox((bbox lab) smoothed 2);
>> else:
>> if mode=7:
>> interim labeloffset:=(u/8);
>> fi;
>> lab:=thelabel@#(txt, pos);
>> if mode>1:
>> pickup PenD
>> fi;
>> if mode=2:
>> process_uplabel;
>> elseif mode=3:
>> process_downlabel;
>> elseif mode=4:
>> process_updownlabel;
>> elseif mode=5:
>> process_circledlabel;
>> elseif mode=6:
>> process_boxedlabel;
>> elseif mode=7:
>> process_label(pos,rot); % station name
>> elseif mode=8:
>> process_filledlabel(pos, rot);
>> else:
>> process_label(pos,rot);
>> fi;
>> fi;
>> enddef;
>>
>> vardef set_label_level (expr mylevel)=
>> maxl := scantokens(mylevel);
>> enddef;
>>
>>
>> def p_u_label_MY (expr P,R,S,A)=
>> T:=identity shifted P;
>> U:=(0,0);
>> save lvl;
>> save style;
>> if known ATTR_style:
>> style:= scantokens(ATTR_style);
>> else:
>> style :=0;
>> fi;
>> if known ATTR_text:
>> if known ATTR_lvl:
>> lvl := scantokens(ATTR_lvl);
>> else: lvl :=0;
>> fi;
>> if lvl < maxl+1:
>> U:=(S*u*(length ATTR_text)/4,S*u*(length
>> ATTR_text)/4);
>> create_styled_label(ATTR_text,P,R,S,A,style);
>> else:;
>> fi;
>> fi;
>> enddef;
>> initsymbol("p_u_label_MY");
>>
>>
>> % https://www.mail-archive.com/therion@speleo.sk/msg07234.html
>> % define a custom attribute called label_mode
>>
>> vardef create_styled_label (expr plaintext,P,R,S,A,defaultstyle)=
>> save textsize, style, thetext;
>> string textsize;
>> if S = 0.5:
>> textsize:="\thtinysize";
>> elseif S = 0.7:
>> textsize:="\thsmallsize";
>> elseif S = 1.4:
>> textsize:="\thlargesize";
>> elseif S = 2:
>> textsize:="\thhugesize";
>> else: % normal is 1
>> textsize:="\thnormalsize";
>> fi;
>> if known ATTR_labelstyle:
>> style:=scantokens(ATTR_labelstyle);
>> else:
>> style:=defaultstyle;
>> fi;
>> picture thetext;
>> thetext:=thTEX("\thframed {" & textsize & " " & plaintext &
>> "}");
>> if A = (-1,1):
>> p_label.ulft(thetext,P,R,style);
>>
>> elseif A = (0,1):
>> p_label.top(thetext,P,R,style);
>>
>> elseif A = (1,1):
>> p_label.urt(thetext,P,R,style);
>>
>> elseif A = (-1,0):
>> p_label.lft(thetext,P,R,style);
>>
>> elseif A = (1,0):
>> p_label.rt(thetext,P,R,style);
>>
>> elseif A = (-1,-1):
>> p_label.llft(thetext,P,R,style);
>>
>> elseif A = (0,-1):
>> p_label.bot(thetext,P,R,style);
>>
>> elseif A = (1,-1):
>> p_label.lrt(thetext,P,R,style);
>>
>> else:
>> p_label(thetext,P,R,style);
>>
>> fi;
>> enddef;
>>
>> endcode
>> endlayout
>>
>>
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