Re: [NTG-context] presentations in ConTeXt

Mojca Miklavec wrote:

On 5/23/05, 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?

What kind of picture do you have? If you have .jpg/.png/..., you can get (x,y) position of the pixel where the center of circle should be.

One possibility is to create a new metapost figure and draw the circle on it using the measured coordinates:

(This circles the blue tulip on http://contextgarden.net/images/6/65/Kochloewe_c.jpg.)

\setupcolors[state=start] \starttext \startuseMPgraphic{CircleBlueTulip} % center point pair size, c; % figure will be 10 cm wide scale := 10cm/400;

% center of the blue tulip is on (219,333), image is 400*460 size := (400,460) scaled scale; c := (222,460-330) scaled scale; % diameter of the circle should be 50 pixels d := 50scale;

pickup pencircle scaled 2pt;

externalfigure "Kochloewe_c.jpg" xyscaled size; draw fullcircle scaled d shifted c withcolor red; \stopuseMPgraphic

\useMPgraphic{CircleBlueTulip}

\stoptext

I believe there exists a more straightforward way if you make uniqueMPgraphic and specify coordinate fractions of the circle to be drawn, but if you say:

\framed[background=SomeGraphicWithACircle]{\externalfigure[Kochloewe_c][width=10cm]}, the circle (if any) is drawn behind the figure and cannot be used as such. Unless you specify the figure in a new layer and draw both layers in the proper order.

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,...} Vit