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

        private static IDisposable DrawBackGlassCenter(RectangleF drawRect,
                                                       Color color1,
                                                       Color color2,
                                                       Color glassColor1,
                                                       Color glassColor2,
                                                       float factorX,
                                                       float factorY,
                                                       VisualOrientation orientation,
                                                       Graphics g,
                                                       float glassPercent,
                                                       IDisposable memento)
        {
            // Cannot draw a path that contains a zero sized element
            if ((drawRect.Width > 0) && (drawRect.Height > 0))
            {
                MementoDouble cache;

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

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

                // Draw the gradient effect background
                DrawBackGlassBasic(drawRect, color1, color2,
                                   glassColor1, glassColor2,
                                   factorX, factorY,
                                   orientation, g,
                                   glassPercent,
                                   ref cache.first);

                bool generate = true;
                MementoBackGlassCenter cacheThis;

                // Access a cache instance and decide if cache resources need generating
                if ((cache.second == null) || !(cache.second is MementoBackGlassCenter))
                {
                    if (cache.second != null)
                        cache.second.Dispose();

                    cacheThis = new MementoBackGlassCenter(drawRect, color2);
                    cache.second = cacheThis;
                }
                else
                {
                    cacheThis = (MementoBackGlassCenter)cache.second;
                    generate = !cacheThis.UseCachedValues(drawRect, color2);
                }

                // Do we need to generate the contents of the cache?
                if (generate)
                {
                    // Dispose of existing values
                    cacheThis.Dispose();

                    cacheThis.path = new GraphicsPath();
                    cacheThis.path.AddEllipse(drawRect);
                    cacheThis.bottomBrush = new PathGradientBrush(cacheThis.path);
                    cacheThis.bottomBrush.CenterColor = color2;
                    cacheThis.bottomBrush.CenterPoint = new PointF(drawRect.X + (drawRect.Width / 2), drawRect.Y + (drawRect.Height / 2));
                    cacheThis.bottomBrush.SurroundColors = new Color[] { Color.Transparent };
                }

                g.FillRectangle(cacheThis.bottomBrush, drawRect);
            }

            return memento;
        }