ConTeXt meeting and the annotated cow

[Axel Kielhorn via ntg-context <ntg-context@ntg.nl>]

Hello,

last week I learned something about MetaPost at the context meeting.
Thanks Taco!

First a little background:

I write a lot of documentation and sometimes I need to include a picture with annotations.
Until now I used a drawing program to add text and arrows.
This has one disadvantage, these annotations are not translated.
I have to prepare a set of pictures for every language.

Well, that changed last week.
Here is my first try (actually the 4th iteration):

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\setupexternalfigures[location=default]
\starttext

\startMPinclusions
%draft := 0;
draft := 1;

color mycolor;

if draft = 1 :
	mycolor := red ;
else:
	mycolor := .4white ;
fi ;

% Draw a grid to count locations

def gridscaled =
pair ur;
ur = urcorner currentpicture;

width :=  xpart ur;
height := ypart ur;

xstep := ceiling(width / 10);
ystep := ceiling(height / 10);

if draft = 1:
counter := 1;
for i = xstep step xstep until width :
	draw (i, 0 ) -- (i, height);
	label.rt(counter, (i , 0.5 cm));
	counter := counter + 1 ;
endfor;

counter := 1;
for i = ystep step ystep until height :
	draw (0, i) -- (width, i);
	label.top(counter, (0.5 cm, i ));
	counter := counter + 1 ;
endfor;
fi;
enddef;
% Bottom: The annotation is at the bottom of the start point                              
def annotb (expr a,  b, c, d) (text t) =
label.bot (t, (a * xstep,  b * ystep));
	drawarrow (a * xstep, b * ystep) -- ( c * xstep, d * ystep)
		withpen pencircle scaled .8mm withcolor white;
	drawarrow (a * xstep, b * ystep) -- ( c * xstep, d * ystep)
		withpen pencircle scaled .5mm withcolor mycolor;
enddef ;
% Top: The annotation is on top of the start point                              
def annott (expr a,  b, c, d) (text t) =
label.top (t, (a * xstep,  b * ystep));
	drawarrow (a * xstep, b * ystep) -- ( c * xstep, d * ystep)
		withpen pencircle scaled .8mm withcolor white;
	drawarrow (a * xstep, b * ystep) -- ( c * xstep, d * ystep)
		withpen pencircle scaled .5mm withcolor mycolor;
enddef ;
% Right: The annotation is on the right of the start point                              
def annotr (expr a,  b, c, d) (text t) =
label.rt (t, (a * xstep,  b * ystep));
	drawarrow (a * xstep, b * ystep) -- ( c * xstep, d * ystep)
		withpen pencircle scaled .8mm withcolor white;
	drawarrow (a * xstep, b * ystep) -- ( c * xstep, d * ystep)
		withpen pencircle scaled .5mm withcolor mycolor;
enddef ;
% Left: The annotation is on the left of the start point                              
def annotl (expr a,  b, c, d) (text t) =
label.lft (t, (a * xstep,  b * ystep));
	drawarrow (a * xstep, b * ystep) -- ( c * xstep, d * ystep)
		withpen pencircle scaled .8mm withcolor white;
	drawarrow (a * xstep, b * ystep) -- ( c * xstep, d * ystep)
		withpen pencircle scaled .5mm withcolor mycolor;
enddef ;
\stopMPinclusions

\startMPpage
% Picture
draw externalfigure "cow.pdf" xsized 16cm;
% Grid
gridscaled;
% Text
annotb (1, 5, .8, 7.3, "Maul");
annotb (6, 2, 7, 3.2, "Euter");
annott (9.2, 9.5, 9.6, 3, "Schwanz");
annotb (3, -.5, 3.1, .9, "Huf");
annotb (3, -.5, 3.9, 1.1, "");

\stopMPpage

\startMPpage
% Picture
draw externalfigure "cow.pdf" xsized 10cm;
% Grid
gridscaled;
% Text
annotb (1, 5, .8, 7.3, "Maul");
annotb (6, 2, 7, 3.2, "Euter");
annott (9.2, 9.5, 9.6, 3, "Schwanz");
annotb (3, -.5, 3.1, .9, "Huf");
annotb (3, -.5, 3.9, 1.1, "");

\stopMPpage

\stoptext

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

There are still some further ideas and a lot to learn for me:
- multi line annotations
- a transparent white background
- a frame around the text
- a link to the section where the part is explained 
- moving to one command with the orientation as an argument

Comments and improvements are welcome.

Greetings
Axel
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