[Therion] My map-connection symbol has broken recently

Sat Apr 24 11:21:36 CEST 2021

Somewhere between Therion 5.5.7+67fffb0 (2021-02-22) and Therion
5.5.7+c43b32a (2021-03-08) (hope those are the right versions - I might have
got confused) the behaviour of my line arrows and map-connections has
changed.

I use some modified/customised code for these, which I last edited in 2018,
so while this recent change in behaviour might be a consequence of my clumsy
coding, the change is triggered somewhere between those two development
releases.

Therion calls the metapost definition l_arrow to draw both arrows and map
connections, so to some extent the appearance of each is tied together.

I'm just wondering if I should tidy up my symbol definition code (I know I
should) or whether something has been broken slightly in the recent Therion
versions?

This is what I used to have, with Therion 5.5.7+67fffb0 (2021-02-22) and
earlier.

And for arrows, these small filled heads are what I used to get

With Therion 5.5.7+c43b32a (2021-03-08) this is what I now get

 Same is happening with Therion 5.5.7+f94faef (2021-04-23)

Looks like the arrow heads on a line arrow now are drawn wider, such that a
gap appears inside of the arrow head, dependant on the arc of the line on
which it is drawn.

And somehow the arrow head on the map-connection line has become fat and
blobby.  The pen width appears to have grown very wide.

As though my custom code is no longer being used for arrow heads?

My custom code for map-connections, last edited in May 2018 as below.

Aside from the problem I have described above, I would like the arrow lines
to be narrower than the map connection lines, and the arrow heads for line
arrows to be small and the arrow heads for map connections to be large.

Three years ago when I tried I could not make it work, but maybe as a result
of this someone can give some guidance.  

Having mapconnection call l_arrow brings about a nice degree of consistency,
but can be frustrating where discrete differences are desired.

If anyone knows how to morph the arrow heads to follow the curve of the
line, that would be great as well.  To avoid the disjointed examples on the
left above.

Bruce

#ARROW and MAP-CONNECTION REDEFINITIONS

#--------------------------

code metapost

% Q = 0 -- no arrows

% 1 -- end

% 2 -- begin

% 3 -- both

def l_arrow (expr P, Q) =

T:=identity;

pickup PenB;

thdraw P;

p := (-.1u,-.5u)--(0,0)--(.1u,-.5u)--cycle; 

% 0.25 changed to .5 and close end to get nicer arrowhead

if odd Q:

thfilldraw p rotated (angle(thdir(P,0))+90) 

shifted (point 0 of P);

fi;

if Q>1:

thfilldraw p rotated (angle(thdir(P,length P))-90) 

shifted (point infinity of P);

fi;

enddef;

def l_mapconnection (expr P) =

thdrawoptions(dashed dashpattern(on 1bp off 2bp on 1bp off 2bp) 

scaled (2 * optical_zoom) withpen PenB);

%draw map-connection line with arrowhead at end

l_arrow(P,1); %How to double or triple arrowhead size with this call?

%draw dot at start of map-connection line

thdraw point infinity of P withpen pencircle scaled 0.3u; 

%Why infinity and not 0 for dot at start of line?? 

%If point before arrow head, then point does not render in legend but does
on map?? 

thdrawoptions();

enddef;

endcode

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