LayoutFarm.RenderBoxes.HitChain.SetStartTestPoint C# (CSharp) Method

        public void SetStartTestPoint(int x, int y)
        {
            testPointX = x;
            testPointY = y;
            startTestX = x;
            startTestY = y;
        }

        static RenderElement HitTestOnPreviousChain(HitChain hitPointChain, HitChain previousChain, int x, int y)
        {
#if DEBUG
            if (hitPointChain == previousChain)
            {
                throw new NotSupportedException();
            }
#endif

            if (previousChain.Count > 0)
            {
                previousChain.SetStartTestPoint(x, y);
                //test on prev chain top to bottom
                int j = previousChain.Count;
                for (int i = 0; i < j; ++i)
                {
                    HitInfo hitInfo = previousChain.GetHitInfo(i);
                    RenderElement elem = hitInfo.hitElement;
                    if (elem != null && elem.VisibleAndHasParent)
                    {
                        if (elem.Contains(hitInfo.point))
                        {
                            RenderElement found = elem.FindUnderlyingSiblingAtPoint(hitInfo.point);
                            if (found == null)
                            {
                                Point leftTop = elem.Location;
                                hitPointChain.OffsetTestPoint(leftTop.X, leftTop.Y);
                                hitPointChain.AddHitObject(elem);
                                //add to chain
                            }
                            else
                            {
                                break;
                            }
                        }
                    }
                    else
                    {
                        break;
                    }
                }
            }
            //---------------------------------
            if (hitPointChain.Count > 0)
            {
                var commonElement = hitPointChain.GetHitInfo(hitPointChain.Count - 1).hitElement;
                hitPointChain.RemoveCurrentHit();
                return commonElement;
            }
            else
            {
                return null;
            }
        }