System.Windows.Forms.XplatUIX11.GetReversibleControlGC C# (CSharp) Method

		IntPtr GetReversibleControlGC (Control control, int line_width)
		{
			XGCValues	gc_values;
			IntPtr		gc;

			gc_values = new XGCValues();

			gc_values.subwindow_mode = GCSubwindowMode.IncludeInferiors;
			gc_values.line_width = line_width;
			gc_values.foreground = XBlackPixel(DisplayHandle, ScreenNo);

			// This logic will give us true rubber bands: (libsx, SANE_XOR)
			//mask = foreground ^ background; 
			//XSetForeground(DisplayHandle, gc, 0xffffffff);
			//XSetBackground(DisplayHandle, gc, background);
			//XSetFunction(DisplayHandle,   gc, GXxor);
			//XSetPlaneMask(DisplayHandle,  gc, mask);


			gc = XCreateGC(DisplayHandle, control.Handle, new IntPtr ((int) (GCFunction.GCSubwindowMode | GCFunction.GCLineWidth | GCFunction.GCForeground)), ref gc_values);
			uint foreground;
			uint background;

			XColor xcolor = new XColor();

			xcolor.red = (ushort)(control.ForeColor.R * 257);
			xcolor.green = (ushort)(control.ForeColor.G * 257);
			xcolor.blue = (ushort)(control.ForeColor.B * 257);
			XAllocColor(DisplayHandle, DefaultColormap, ref xcolor);
			foreground = (uint)xcolor.pixel.ToInt32();

			xcolor.red = (ushort)(control.BackColor.R * 257);
			xcolor.green = (ushort)(control.BackColor.G * 257);
			xcolor.blue = (ushort)(control.BackColor.B * 257);
			XAllocColor(DisplayHandle, DefaultColormap, ref xcolor);
			background = (uint)xcolor.pixel.ToInt32();

			uint mask = foreground ^ background; 

			XSetForeground(DisplayHandle, gc, (UIntPtr)0xffffffff);
			XSetBackground(DisplayHandle, gc, (UIntPtr)background);
			XSetFunction(DisplayHandle,   gc, GXFunction.GXxor);
			XSetPlaneMask(DisplayHandle,  gc, (IntPtr)mask);

			return gc;
		}