自定义DataGrid WinRT渲染大小0

Question

我正在尝试在WinRT中构建一个DataGrid。当我开始这个时，DataGrid有它的全尺寸。 但是当我用WinRTXamlToolkit.Debugging工具检查时，我看到我的_itemsPanel的渲染大小为0。 我认为找到问题的最简单方法是将整个代码粘贴到此处^^

        <local:DataGrid ItemsSource="{Binding Material}">
            <local:DataGrid.ItemTemplate>
                <DataTemplate>
                    <Grid Background="White">
                        <TextBlock Text="{Binding Name}" Margin="5" />
                    </Grid>
                </DataTemplate>
            </local:DataGrid.ItemTemplate>
        </local:DataGrid>

这是我的DataGrid类：

    public class DataGrid : Panel
    {
        private StackPanel _itemsPanel;

        public DataTemplate ItemTemplate { get; set; }

        public static readonly DependencyProperty ItemsSourceProperty =
            DependencyProperty.Register("ItemsSource",
                                        typeof(IEnumerable<Object>),
                                        typeof(DataGrid),
                                        new PropertyMetadata(0, ItemsSourceChangedCallback));

        private static void ItemsSourceChangedCallback(DependencyObject d, DependencyPropertyChangedEventArgs args)
        {
            if (args.NewValue == null)
                return;

            if (args.NewValue == args.OldValue)
                return;

            DataGrid dataGrid = d as DataGrid;

            if (dataGrid == null)
                return;

            var obsList = args.NewValue as INotifyCollectionChanged;

            if (obsList != null)
            {
                dataGrid.Render();
            }
        }

        public IEnumerable<Object> ItemsSource
        {
            get { return (IEnumerable<Object>)GetValue(ItemsSourceProperty); }
            set { SetValue(ItemsSourceProperty, value); }
        }

        public DataGrid()
        {
            _itemsPanel = new StackPanel();
            _itemsPanel.Height = 800;
            _itemsPanel.Width = 400;
            _itemsPanel.Margin = new Thickness(10, 10, 10, 10);

            _itemsPanel.Background = new SolidColorBrush(Colors.White);
            Children.Add(_itemsPanel);
        }

        public void Render()
        {
            _itemsPanel.Children.Clear();

            foreach (object item in ItemsSource)
            {
                FrameworkElement element = ItemTemplate.LoadContent() as FrameworkElement;

                if (element == null)
                    return;

                element.DataContext = item;

                _itemsPanel.Children.Add(element);
            }
        }

        protected override Size ArrangeOverride(Size finalSize)
        {
            return base.ArrangeOverride(finalSize);
        }

        protected override Size MeasureOverride(Size availableSize)
        {
            this.Clip = new RectangleGeometry { Rect = new Rect(0, 0, availableSize.Width, availableSize.Height) };

            foreach (FrameworkElement container in Children)
            {
                container.Measure(new Size(Double.PositiveInfinity, Double.PositiveInfinity));
            }

            return availableSize;
        }
    }

希望你能帮助我:)。