set_operator


Description:

public void set_operator (Operator op)

Example: Layers:

public static int main (string[] args) {
// Layer 1:
Cairo.ImageSurface surface1 = new Cairo.ImageSurface (Cairo.Format.ARGB32, 200, 200);
Cairo.Context context1 = new Cairo.Context (surface1);

context1.set_source_rgba (1, 0, 0, 1);
context1.set_line_width (5);
context1.move_to (0, 0);
context1.line_to (200, 200);
context1.stroke ();

// Layer 2:
Cairo.ImageSurface surface2 = new Cairo.ImageSurface (Cairo.Format.ARGB32, 200, 200);
Cairo.Context context2 = new Cairo.Context (surface2);

context2.set_source_rgba (0, 0, 1, 1);
context2.set_line_width (5);
context2.move_to (200, 0);
context2.line_to (0, 200);
context2.stroke ();

// Joined:
Cairo.ImageSurface surface = new Cairo.ImageSurface (Cairo.Format.ARGB32, 200, 200);
Cairo.Context context = new Cairo.Context (surface);

context.set_operator (Cairo.Operator.OVER);
context.set_source_surface (context1.get_target (), 0, 1);
context.paint ();

context.set_operator (Cairo.Operator.OVER);
context.set_source_surface (context2.get_target (), 0, 1);
context.paint_with_alpha (0.5);

surface.write_to_png ("img.png");

return 0;
}

valac --pkg cairo layers.vala