[NTG-context] Putting things over a figure

Hans Hagen pragma at wxs.nl
Sun Apr 23 20:32:06 CEST 2006


nico wrote:
> Hello,
>
> I need a mechanism with which I can put several things (text, image) at a  
> precise position over a figure. The position is expressed in percentage  
> (x,y) of the figure dimensions. The lower-left corner is (0,0).
>   
> I did the following that works for my own needs, but maybe a higher level  
> interface (layer?) could do the same. Any comment or improvement is  
>   
i'd go for layers
> welcome.
>
>
> \newdimen\overfigwd
> \newdimen\overfight
>
> % Put the figure and define the x/y percentage factor for the calspairs.
> \def\startoverfig
>    {\dodoubleempty\dostartoverfig}
>
> \def\dostartoverfig[#1][#2]%
>    {\bgroup
>     \setbox\scratchbox\hbox{\externalfigure[#1][#2]}%
>     \overfigwd=\wd\scratchbox
>     \overfight=\ht\scratchbox
>     \setuppositioning[unit=pt,
>                       xfactor=\withoutpt\the\dimexpr(\overfigwd/100),
>                       yfactor=\withoutpt\the\dimexpr(\overfight/100)]%
>     \startpositioning
>       \position(0,0){\box\scratchbox}}
>
> \def\stopoverfig
>    {\stoppositioning\egroup}
>
> % Put (centered) at the position (x%,y%) on the figure.
> % The lower-left corner is (0,0)
> \def\calspair(#1,#2)#3%
>    {\setbox0\hbox{#3}%
>     \position[xoffset=\dimexpr(-\wd0/2),
>               yoffset=\dimexpr(-\ht0/2)](#1,{\numexpr(100-#2)}){#3}}
>
> %%
>
> \setupcolors[state=start]
>
> \starttext
>
> \startoverfig[duck-small]
>    \calspair(0,0){A}
>    \calspair(100,100){B}
> \stopoverfig
>
> \startoverfig[duck-small][width=4cm,frame=on]
>    \calspair(0,0){A}
>    \calspair(100,100){B}
>    \calspair(50,50){\framed[background=color,backgroundcolor=green]{Hello}}
> \stopoverfig
>
> \startoverfig[unknown]
>    \calspair(30,0){A}
>    \calspair(100,100){B}
> \stopoverfig
>
> \stoptext
>
> Regards,
> BG
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> ntg-context at ntg.nl
> http://www.ntg.nl/mailman/listinfo/ntg-context
>   


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