Re: [LAD] OT: gtk rectangle with opacity

gboolean box_expose(GtkWidget *wi, GdkEventExpose *ev, gpointer data)
    {
      cairo_t *cr;
      // create a cairo context //
      cr = gdk_cairo_create(wi->window);

      double x0 = wi->allocation.x;
      double y0 = wi->allocation.y;
      double rect_width = wi->allocation.width;
      double rect_height = wi->allocation.height;

      cairo_rectangle (cr, x0,y0,rect_width,rect_height+3);
      cairo_set_source_rgba (cr, 0, 0, 0, 0.5); // a set the opacity
level
      cairo_fill (cr);
      cairo_destroy(cr);
     }
draw a transparent black rectangle to the calling widget.
You can connect it with to make sure it will redraw when needed.

g_signal_connect(widget, "expose-event", G_CALLBACK(box_expose), NULL);

more examples you could found here
 http://cairographics.org/samples/

regards hermann

Am Montag, den 28.12.2009, 04:30 +1100 schrieb Patrick Shirkey:
> Hi,
>
> Does anyone have an example in c of drawing a gdk_rectangle with opacity
> in the foreground color?
>
> There's several examples in python floating around that use the cairo
> but I can't find a nice example in c.
>
>
>
>
> Cheers.
>

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Received on Mon Dec 28 00:15:02 2009