[NTG-context] Clip an image with a svg

[NTG-context] Clip an image with a svg

[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.

The SVG is something like this:

<?xml version="1.0" encoding="UTF-8"?>
<!-- Created with Inkscape (http://www.inkscape.org/) -->
<svg width="20.887mm" height="17.613mm" version="1.1" viewBox="0 0 
20.887 17.613" xmlns="http://www.w3.org/2000/svg">
  <g transform="translate(152.66 -101.94)">
   <path d="m-150.94 114.93c-0.5424-1.3121-0.58209-2.9382 0.18256-5.2163 
2.3566-7.0175 11.139-8.7098 15.878-3.0594 7.6978 8.7032-11.506 
16.052-16.06 8.2756" fill="none" stroke="#dd4901" stroke-linecap="round" 
stroke-width="2"/>
  </g>
</svg>

I guess that there might be a way to translate this to Metafun or 
Metapost, if I can't use SVG directly.

In my real life use case I want to have a bleeding image at the top or 
the bottom of the page which can be clipped by the form while size and 
position of the form relative to the image and relative to the page 
shall be set by parameters either in \clip or in the definition of the 
MPclip.

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

[Wolfgang Schuster]

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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