Thanks for the pointer, Aditya.  I had not seen this, but I couldn't get it to do what I wanted.

I don't fully understand what nofill does and how it interacts with fill and eofill.  I get strange results sometimes.  One complication, though, is that the picture I get from lmt_outline seems to cover some part (small area around the joining part) twice, so that messes up the even/odd logic of eofill.

Here is one of the things I tried:

\starttext
\definedfont[dejavusansmono*arabic]
\setupalign[r2l]
\startMPcode
picture op; op := lmt_outline [
  text = "سلام",
  kind = "fillup",
  align = "r2l",
] scaled 6mm;
for i within op:
  nofill pathpart i;
endfor;
for i within op:
eofill pathpart i withpen pencircle scaled 1mm;
endfor;
\stopMPcode
\stoptext


On Wed, Mar 10, 2021 at 11:09 PM Aditya Mahajan <adityam@umich.edu> wrote:
On Wed, 10 Mar 2021, Mohammad Hossein Bateni wrote:

> Hello,
>
> Hans said he's in the metapost mode now :)
>
> I have used lmt_outline in the following example and it is really an
> improvement over the previous outline "effect" because one can set the
> fillcolor and drawcolor separately.  (that was not possible before, right?)
>
> \starttext
> \definedfont[dejavusansmono*arabic]
> \setupalign[r2l]
> \startMPcode
> draw lmt_outline [
>   text = "سلام",
>   drawcolor = "red",
>   fillcolor = "white",
>   kind = "reverse",
>   align = "r2l",
> ] scaled 3mm;
> \stopMPcode
> \stoptext
>
> 1. This works well on a plain background.  I can specify the background
> color in fillcolor and get the outline effect.  When the background is an
> image, this does not work too well.  Can we use some clip trickery to allow
> for "transparent" fill?  Ideally I want to set the fillcolor to a special
> value that would lead to only the outlines drawn.

Have you seen this example on the wiki which uses nofill:

https://wiki.contextgarden.net/Cover_Pages#Empty_or_Transparent_letters

Aditya___________________________________________________________________________________
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