[NTG-context] Re: Clip an image with a svg

[Wolfgang Schuster <wolfgang.schuster.lists@gmail.com>]

Am 03.01.2025 um 16:53 schrieb juh+ntg-context--- via ntg-context:
> Dear all,
> 
> I found this example in the garden.
> 
> \startMPclip{circleclip}
>       clip currentpicture to fullcircle shifted (.5,.5)
>         xscaled \width yscaled \height ;
> \stopMPclip
> 
> \clip[nx=1,ny=1,mp=circleclip]{\externalfigure[hacker.png]}
> 
> Aside from the fact that I failed to understand the shifted argument by 
> playing around with values, I wonder if it is possible to use a SVG as 
> clip for an image.


In the following example the yellow square is your picture, when you use 
fullcircle without the shift you clipped image shows only the bottom 
left corner (the part where the red circle and yellow square overlap).

To get the center of the picture you can either ship fullcircle by .5 in 
the x and y direction or use unitcircle.

%%%% begin example
\startMPpage[offset=1cm]

fill unitsquare scaled 5cm withcolor "yellow" ;

draw hlingrid(0, 10, 1, 10cm, 10cm) shifted(-5cm,-5cm) ;
draw vlingrid(0, 10, 1, 10cm, 10cm) shifted(-5cm,-5cm) ;

draw origin withpen pencircle scaled 10 ;

draw fullcircle scaled 5cm withcolor "red"   withpen pencircle scaled 5;

draw unitcircle scaled 5cm withcolor "green" withpen pencircle scaled 5;

\stopMPpage
%%%% end example

Wolfgang

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