[cairo] How to draw a inverted area?

[Carlos Garcia Campos]

Excerpts from Magicloud Magiclouds's message of lun jun 07 13:44:21 +0200 2010:
> I cannot find that operator. I think you meant cairo_operator_t?

Yes, you need cairo >= 1.9.2

> typedef enum _cairo_operator {
>     CAIRO_OPERATOR_CLEAR,
> 
>     CAIRO_OPERATOR_SOURCE,
>     CAIRO_OPERATOR_OVER,
>     CAIRO_OPERATOR_IN,
>     CAIRO_OPERATOR_OUT,
>     CAIRO_OPERATOR_ATOP,
> 
>     CAIRO_OPERATOR_DEST,
>     CAIRO_OPERATOR_DEST_OVER,
>     CAIRO_OPERATOR_DEST_IN,
>     CAIRO_OPERATOR_DEST_OUT,
>     CAIRO_OPERATOR_DEST_ATOP,
> 
>     CAIRO_OPERATOR_XOR,
>     CAIRO_OPERATOR_ADD,
>     CAIRO_OPERATOR_SATURATE
> } cairo_operator_t;
> 
> On Mon, Jun 7, 2010 at 6:03 PM, Carlos Garcia Campos <carlosgc at gnome.org> wrote:
> > Excerpts from Magicloud Magiclouds's message of lun jun 07 09:44:10 +0200 2010:
> >> Hi, sorry the subject is not clear.
> >> I mean that, first I draw something in the cairo context, then I draw
> >> a circle in it, which acts like a invert mask. All colors in its area
> >> are inverted.
> >
> > I think filling with white with the difference operator is what you
> > want
> >
> > cairo_set_source_rgb (cr, 1., 1., 1.);
> > cairo_set_operator (cr, CAIRO_OPERATOR_DIFFERENCE);
> > cairo_fill(cr);
> >
> >> I thought xor operator helped, but it did not....
> >> Thanks.
> >
> > Regards,
> >
> 
-- 
Carlos Garcia Campos
PGP key: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x523E6462
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