Microsoft.Phone.Controls.Primitives.LoopingSelectorItem.InsertAfter C# (CSharp) Метод

        internal void InsertAfter(LoopingSelectorItem after)
        {
            Next = after.Next;
            Previous = after;

            if (after.Next != null)
            {
                after.Next.Previous = this;
            }

            after.Next = this;
        }

        /// <summary>
        /// Balances the items.
        /// </summary>
        private void Balance()
        {
            if (!IsReady)
            {
                return;
            }

            double actualItemWidth  = ActualItemWidth;
            double actualItemHeight = ActualItemHeight;

            _additionalItemsCount = (int)Math.Round((ActualHeight * 1.5) / actualItemHeight);

            LoopingSelectorItem closestToMiddle = null;
            int closestToMiddleIndex            = -1;

            if (_itemsPanel.Children.Count == 0)
            {
                // We need to get the selection and start from there
                closestToMiddleIndex        = 0;
                _selectedItem               = closestToMiddle = CreateAndAddItem(_itemsPanel, DataSource.SelectedItem);
                closestToMiddle.Transform.Y = -actualItemHeight / 2;
                closestToMiddle.Transform.X = (ActualWidth - actualItemWidth) / 2;
                closestToMiddle.SetState(LoopingSelectorItem.State.Selected, false);
            }
            else
            {
                closestToMiddleIndex = GetClosestItem();
                closestToMiddle      = (LoopingSelectorItem)_itemsPanel.Children[closestToMiddleIndex];
            }

            if (IsExpanded)
            {
                int itemsBeforeCount;
                LoopingSelectorItem firstItem = GetFirstItem(closestToMiddle, out itemsBeforeCount);

                int itemsAfterCount;
                LoopingSelectorItem lastItem = GetLastItem(closestToMiddle, out itemsAfterCount);

                // Does the top need items?
                if (itemsBeforeCount < itemsAfterCount || itemsBeforeCount < _additionalItemsCount)
                {
                    while (itemsBeforeCount < _additionalItemsCount)
                    {
                        object newData = DataSource.GetPrevious(firstItem.DataContext);
                        if (newData == null)
                        {
                            // There may be room to display more items, but there is no more data.
                            _maximumPanelScroll = -firstItem.Transform.Y - actualItemHeight / 2;
                            if (_isAnimating && _panelAnimation.To.Value > _maximumPanelScroll)
                            {
                                Brake(_maximumPanelScroll);
                            }
                            break;
                        }

                        LoopingSelectorItem newItem = null;

                        // Can an item from the bottom be re-used?
                        if (itemsAfterCount > _additionalItemsCount)
                        {
                            newItem  = lastItem;
                            lastItem = lastItem.Previous;
                            newItem.Remove();
                            newItem.Content = newItem.DataContext = newData;
                        }
                        else
                        {
                            // Make a new item
                            newItem             = CreateAndAddItem(_itemsPanel, newData);
                            newItem.Transform.X = (ActualWidth - actualItemWidth) / 2;
                        }

                        // Put the new item on the top
                        newItem.Transform.Y = firstItem.Transform.Y - actualItemHeight;
                        newItem.InsertBefore(firstItem);
                        firstItem = newItem;

                        ++itemsBeforeCount;
                    }
                }

                // Does the bottom need items?
                if (itemsAfterCount < itemsBeforeCount || itemsAfterCount < _additionalItemsCount)
                {
                    while (itemsAfterCount < _additionalItemsCount)
                    {
                        object newData = DataSource.GetNext(lastItem.DataContext);
                        if (newData == null)
                        {
                            // There may be room to display more items, but there is no more data.
                            _minimumPanelScroll = -lastItem.Transform.Y - actualItemHeight / 2;
                            if (_isAnimating && _panelAnimation.To.Value < _minimumPanelScroll)
                            {
                                Brake(_minimumPanelScroll);
                            }
                            break;
                        }

                        LoopingSelectorItem newItem = null;

                        // Can an item from the top be re-used?
                        if (itemsBeforeCount > _additionalItemsCount)
                        {
                            newItem   = firstItem;
                            firstItem = firstItem.Next;
                            newItem.Remove();
                            newItem.Content = newItem.DataContext = newData;
                        }
                        else
                        {
                            // Make a new item
                            newItem             = CreateAndAddItem(_itemsPanel, newData);
                            newItem.Transform.X = (ActualWidth - actualItemWidth) / 2;
                        }

                        // Put the new item on the bottom
                        newItem.Transform.Y = lastItem.Transform.Y + actualItemHeight;
                        newItem.InsertAfter(lastItem);
                        lastItem = newItem;

                        ++itemsAfterCount;
                    }
                }

                _temporaryItemsPool = null;
            }
        }