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

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

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

                    cache = new MementoTriple();
                    memento = cache;
                }
                else
                {
                    cache = (MementoTriple)memento;
                }

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

                // Reduce size on all but the upper edge
                ModifyRectByEdges(ref rect, 1, 0, 1, 1, orientation);

                // Draw the inside areas as a glass effect
                cache.second = DrawBackGlassRadial(rect, backColor1, backColor2,
                                                   _glassColorTopD, _glassColorBottomD,
                                                   5f, 1.2f, orientation, context.Graphics,
                                                   glassPercent, cache.second);

                // Widen back to original
                ModifyRectByEdges(ref rect, -1, 0, -1, 0, orientation);

                cache.third = DrawBackDarkEdge(rect, ControlPaint.Dark(backColor1),
                                               3, orientation, context.Graphics,
                                               cache.third);
            }

            return memento;
        }