ComponentFactory.Krypton.Toolkit.RenderGlassHelpers.DrawBackGlassTrackingPercent C# (CSharp) Method

        private static IDisposable DrawBackGlassTrackingPercent(RenderContext context,
                                                                Rectangle rect,
                                                                Color backColor1,
                                                                Color backColor2,
                                                                VisualOrientation orientation,
                                                                GraphicsPath path,
                                                                float glassPercent,
                                                                IDisposable memento)
        {
            using (Clipping clip = new Clipping(context.Graphics, path))
            {
                MementoDouble cache;

                if ((memento == null) || !(memento is MementoDouble))
                {
                    if (memento != null)
                        memento.Dispose();

                    cache = new MementoDouble();
                    memento = cache;
                }
                else
                    cache = (MementoDouble)memento;

                // Draw the one pixel border around the area
                cache.first = DrawBackLinearRadial(rect, false,
                                                   ControlPaint.LightLight(backColor2),
                                                   ControlPaint.Light(backColor2),
                                                   ControlPaint.LightLight(backColor2),
                                                   orientation, context.Graphics,
                                                   cache.first);

                // Reduce size of the inside area
                rect.Inflate(-1, -1);

                // Draw the inside area as a glass effect
                cache.second = DrawBackGlassRadial(rect, backColor1, backColor2,
                                                   _glassColorTopL, _glassColorBottomL,
                                                   2f, 1f, orientation, context.Graphics,
                                                   glassPercent, cache.second);
            }

            return memento;
        }