[cairo] Transparency
Jose Hevia
jose.francisco.hevia at gmail.com
Sat Jul 14 03:10:04 PDT 2007
Hello,
I just want to confirm if those are bugs:
I want to clear a surface with cairo,so the screen displays a color
background with transparency, so I do:
cairo_set_source_rgba (new->cr, 0,1,1,0.1);
cairo_set_source_surface (new->cr,new->surface, 0, 0);
cairo_set_operator (new->cr, CAIRO_OPERATOR_CLEAR);
cairo_paint(new->cr);
where new->suface is a "cairo_surface_t" and new->cr "cairo_t". Then I
paste little images with CAIRO_OPERATOR_OVER.
BUG: I can't change clearing color. Is always(0,0,0,0). Is this a bug?
I can clear the surface manually,without cairo, then dispay with
CAIRO_OPERATOR_SOURCE,but:
ANOTHER BUG:Transparency seems a function of the screen luminosity
((R+G+B)/3), instead of alpha--->(255,255.255,0) is always opaque
white, no matter what is behind the window.
Black (0,0,0,255) is opaque through.
System Info: Ubuntu FF with beryl, cairo 1.4.2
Bye
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