Cairo.Context.Mask C# (CSharp) Метод

        public void Mask(Pattern pattern)
        {
            CheckDisposed ();
            NativeMethods.cairo_mask (handle, pattern.Handle);
        }

		public bool OnExpose (Context ctx, Gdk.Rectangle allocation)
		{
			if (frames == 0)
				start = DateTime.UtcNow;
			
			frames ++;
			TimeSpan elapsed = DateTime.UtcNow - start;
			double fraction = elapsed.Ticks / (double) duration.Ticks; 
			double opacity = Math.Sin (Math.Min (fraction, 1.0) * Math.PI * 0.5);
			
			ctx.Operator = Operator.Source;
			
			SurfacePattern p = new SurfacePattern (begin_buffer.Surface);
			ctx.Matrix = begin_buffer.Fill (allocation);
			p.Filter = Filter.Fast;
			ctx.Source = p;
			ctx.Paint ();
			
			ctx.Operator = Operator.Over;
			ctx.Matrix = end_buffer.Fill (allocation);
			SurfacePattern sur = new SurfacePattern (end_buffer.Surface);
#if MONO_1_2_5
			Pattern black = new SolidPattern (new Cairo.Color (0.0, 0.0, 0.0, opacity));
#else
			Pattern black = new SolidPattern (new Cairo.Color (0.0, 0.0, 0.0, opacity), true);
#endif
			//ctx.Source = black;
			//ctx.Fill ();
			sur.Filter = Filter.Fast;
			ctx.Source = sur;
			ctx.Mask (black);
			//ctx.Paint ();
			
			ctx.Matrix = new Matrix ();
			
			ctx.MoveTo (allocation.Width / 2.0, allocation.Height / 2.0);
			ctx.Source = new SolidPattern (1.0, 0, 0);	
			#if debug
			ctx.ShowText (String.Format ("{0} {1} {2} {3} {4} {5} {6} {7}", 
						     frames,
						     sur.Status,
						     p.Status,
						     opacity, fraction, elapsed, start, DateTime.UtcNow));
			#endif
			sur.Destroy ();
			p.Destroy ();
			return fraction < 1.0;
		}