> Fabrice Couvreur <mailto:fabrice1.couvreur@gmail.com>
> 9. Juli 2016 um 12:17
> Hi Wolfgang,
>
> In the first example, so I do not need the command \currentheadnumber 
> but just do:
>
> \setuphead
>    [chapter]
>    [command=\HeadTitle,
>     headstyle=\ss,
>     numbercommand=\Headed]
ConTeXt passes the section number to the argument of the \Headed command.
> But in this second example, using the command 
> \determineheadnumber[chapter], the chapter number is always 0
You need \determineheadnumber[...] each time when the value for 
\currentheadnumber should change.
> \setuppagenumbering[location=footer]
>
> \startusableMPgraphic{NumberHead}
>       picture r ;
>       r := image ( graphictext
>         \MPstring{chapter}
>         scaled 4pt
>         withfillcolor \MPcolor{lightgray}
>         withpen pencircle scaled 1pt ; ) ;
>       draw r ;
>     \stopusableMPgraphic
>
> \defineoverlay[NumberHead][\uniqueMPgraphic{NumberHead}]
>
> \def\processMPheadnumber#1%
>   {\setMPtext{chapter}{\bf#1}
>    \useMPgraphic{NumberHead}}
>
> \setuphead
>    [chapter]
>    [command=\HeadTitle,
>     headstyle=\ss,
>     numbercommand=\processMPheadnumber{\currentheadnumber}]
The following works here.

\startusableMPgraphic{NumberHead}
       picture r ;
       r := image ( graphictext
         "\bf\namedheadnumber{chapter}"
         scaled 4pt
         withfillcolor \MPcolor{lightgray}
         withpen pencircle scaled 1pt ; ) ;
       draw r ;
\stopusableMPgraphic

\def\processMPheadnumber#1%
   {\useMPgraphic{NumberHead}}

\setuphead
    [chapter]
    [command=\HeadTitle,
     headstyle=\ss,
     numbercommand=\processMPheadnumber]

Wolfgang