Re: presentations in ConTeXt

[Mojca Miklavec <mojca.miklavec.lists@gmail.com>]

Vit Zyka wrote:
> Mojca Miklavec wrote:
> > Thomas A. Schmitz wrote:
> >
> >>I am still at a loss how to achieve one thing in ConTeXt that was
> >>pretty easy in Keynote or (shudder) Powerpoint: When I wanted to
> >>highlight something on a map or a picture, I would just draw a red
> >>circle around it. What would be the proper way to do this in ConTeXt?
> >>Adding a layer with a red circle drawn in Metapost, then positioning
> >>it by trial and error? Or can anyone point to a better solution?
> >
...
> > In this case it would be fine to have a \framed[...foreground=...] command :)
> 
> Use
> 
> \framed
>    [background={foreground,BgFront}]
>    {\externalfigure[Kochloewe_c][width=10cm]}}
> 
> Define your picture as BgFront. 'foreground' is fixed word that
> identifies layer 0 (text). So you can stack bacground as follow:
>    background={...,MyLayer-2,MyLayer-1,foreground,MyLayer1,MyLayer2,...}

Uau! Thanks a lot for a very nice hint. So you can make something like that:

\setupcolors[state=start]
\starttext
\setupMPvariables[CircleSomething][dimension={(100,100)},center={(50,50)},r=10]
\startuseMPgraphic{CircleSomething}
	pair dimension, center;
	% TODO: this also has to be passed as parameter!!!
	%       now it stands for: width=10cm
	scale := 10cm/(xpart \MPvar{dimension});
	picture bboxpicture;

	dimension := \MPvar{dimension} scaled scale;
	center := \MPvar{center} scaled scale;
	r := \MPvar{r}*scale;

	pickup pencircle scaled 2pt;

	% proper bounding box
	fill unitsquare xyscaled dimension;
	bboxpicture := currentpicture;
	currentpicture := nullpicture;
	
	draw fullcircle scaled (2*r) shifted center withcolor red;
	setbounds currentpicture to boundingbox bboxpicture;
\stopuseMPgraphic

\defineoverlay[CircleBlueTulip][\uniqueMPgraphic{CircleSomething}{dimension={(400,460)},center={(222,460-330)},r=25}]
\defineoverlay[CircleRedTulip][\useMPgraphic{CircleSomething}{dimension={(400,460)},center={(148,460-330)},r=25}]

\framed[background={foreground,CircleBlueTulip},offset=0pt,strut=no]{\externalfigure[Kochloewe_c][width=10cm]}
\framed[background={foreground,CircleRedTulip},offset=0pt,strut=no]{\externalfigure[Kochloewe_c][width=10cm]}

\stoptext

Mojca