You should use something like:
cairo_set_source_surface(cr, surface, 0, 0);
cairo_paint(cr).
cairo_set_source_rgb(cr, 0, 0, 1);
cairo_rectangle(cr, 300,300, 200, 200);
cairo_stroke(cr);
This will paint the window with surface as source and then draw a blue
rectangle.
Le vendredi 10 août 2012 à 14:09 +0530, Prasanta Sadhukhan a écrit :
>
>
> On Fri, Aug 10, 2012 at 1:22 PM, Jean Brefort
> <jean.brefort@xxxxxxxxxxxxxx> wrote:
> This code is quite strange. Your call to
> cairo_set_source_surface() is
> not useful since you use cairo_set_source_rgb() just after.
> You should
> call cairo_paint() just after cairo_set_source_surface() if
> you want it
> to have any effect.
>
> If I do not call cairo_set_source_rgb(cr, 0, 0, 1); how will get a
> blue rectangle?
> Just having these is giving me a window with black background.
> cairo_set_source_surface(cr, surface, 0, 0);
> cairo_rectangle(cr, 300,300, 200, 200);
> cairo_stroke(cr);
> cairo_paint(cr).
>
> Can you please clarify?
> As I told, I would like to get a blue rectangle in offscreen surface
> and a green rectangle in main visible surface so after final rendering
> of offscreen contents on main window, I would get both rectangles on
> main window.
>
> Regards
> Prasanta
>
> Hope it helps,
> Jean
>
> Le vendredi 10 août 2012 à 13:07 +0530, Prasanta Sadhukhan a
> écrit :
> > expose_event (GtkWidget *widget,GdkEventExpose *event,
> gpointer
> > data)
> > {
> > g_print("draw event main\n");
> >
> > cairo_t *cr = gdk_cairo_create(widget->window);
> > // draw blue rectangle into offscreen
> > cairo_set_source_surface(cr, surface, 0, 0);
> > cairo_set_source_rgb(cr, 0, 0, 1);
> > cairo_rectangle(cr, 300, 300, 200, 200);
> > cairo_stroke(cr);
> > cairo_paint(cr);
> >
> > //draw green rectangle onto main window
> > cairo_set_source_rgb(cr, 0, 1, 0);
> > cairo_rectangle(cr, 100, 100, 200, 200);
> > cairo_stroke(cr)
> > }
> >
> >
> >
>
>
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