[NTG-context] alignment of marginal material

[Hans Hagen]

At 21:40 22/02/2004, Jonathan Nicholl wrote:
>I am trying to write a macro which places a picture in the margin. I would=
=20
>like the centre of the picture to be aligned vertically with the centre of=
=20
>the paragraph in which I call the macro. The following works in simple=
 cases:
>
>\def\hazard#1{%                         The argument is the text of the=20
>paragraph
>         \setbox0=3D\vbox{#1}%             I do this to work out the height=
=20
> of the paragraph
>         \inleft [low] {%
>                 \framed%
>                         [height=3D\ht0,%  This makes the height of the=20
> frame equal to the height of the paragraph
>                         top=3D\vss,%
>                         bottom=3D\vss,%   These two lines centre the=20
> picture in the frame
>                         frame=3Doff]%
>                         {\externalfigure [sharp turn sign]}%
>                 }%
>         #1}%                                            It goes wrong if=
=20
> you replace #1 with \box0
>
>If I type something like
>
>\hazard{=85paragraph text=85}
>
>this produces what I want. But it breaks down with mathematics.
>
>\hazard{%
>         \startformula
>                 =85mathematics=85
>         \stopformula
>}
>
>produces the picture aligned with the bottom of the mathematics.
>
>A solution to this problem escapes me. Can anyone suggest an improved=
 macro?

Here is my 10 minute solution ... if i'm in the mood i can make an option=20
of it

\newcounter\CurrentFigPar

\def\StartFigPar#1%
   {\doglobal\increment\CurrentFigPar
    \placefigure
      [leftmargin,line,none]{}
      {\setbox\scratchbox\hbox{#1}%
      =
 \ifnum\MPp{figpar:b:\CurrentFigPar}=3D\MPp{figpar:e:\CurrentFigPar}\relax
         \scratchdimen\MPy{figpar:b:\CurrentFigPar}%
         \advance\scratchdimen-\MPy{figpar:e:\CurrentFigPar}%
         \advance\scratchdimen-\ht\scratchbox
         \advance\scratchdimen\lineheight
       \else
         \scratchdimen\zeropoint
       \fi
       \vbox{\vskip.5\scratchdimen\box\scratchbox}}%
    \indent\hpos{figpar:b:\CurrentFigPar}{\strut}\ignorespaces}

\def\StopFigPar
   {\removeunwantedspaces\hpos{figpar:e:\CurrentFigPar}{\strut}\endgraf}

\starttext

\input tufte

\StartFigPar{\externalfigure[cow.pdf][width=3D1cm]} \input tufte \StopFigPar

\input tufte

\stoptext=20