控件（集合类）: ItemsControl 的布局控件

/* * ItemsWrapGrid - 虚拟化布局控件，GridView 的默认布局控件（继承自 Panel, 请参见 /Controls/LayoutControl/PanelDemo.xaml） * FirstCacheIndex - 缓存中的第一项在全部数据中的索引位置 * FirstVisibleIndex - 屏幕上显示的第一项在全部数据中的索引位置 * LastCacheIndex - 缓存中的最后一项在全部数据中的索引位置 * LastVisibleIndex - 屏幕上显示的最后一项在全部数据中的索引位置 * CacheLength - 可见区外的需要缓存的数据的大小（以可见区条数大小的倍数为单位），默认值为 4.0 * 比如当可见区可以显示 10 条数据，CacheLength 为 4 时，可见区外的需要缓存的数据的大小则为 4 * 10 = 40，，也就是说整个缓存数据的大小为 10 + 4 * 10 = 50 * 实际测试发现，可能会有一定的偏差，但是大体是准确的 */ using System; using System.Collections.Generic; using System.Linq; using System.Xml.Linq; using Windows.UI.Xaml; using Windows.UI.Xaml.Controls; using Windows.UI.Xaml.Controls.Primitives; using Windows.UI.Xaml.Data; using Windows10.Common; namespace Windows10.Controls.CollectionControl.ItemsControlDemo.LayoutControl { public sealed partial class ItemsWrapGridDemo : Page { public CollectionViewSource MyData { get { XElement root = XElement.Load("SiteMap.xml"); var items = LoadData(root); // 构造数据源 CollectionViewSource source = new CollectionViewSource(); source.IsSourceGrouped = true; source.Source = items; source.ItemsPath = new PropertyPath("Items"); return source; } } private ItemsWrapGrid _itemsWrapGrid1 = null; private ItemsWrapGrid _itemsWrapGrid2 = null; public ItemsWrapGridDemo() { this.InitializeComponent(); this.Loaded += ItemsWrapGridDemo_Loaded; } private void ItemsWrapGridDemo_Loaded(object sender, RoutedEventArgs e) { DispatcherTimer dTimer = new DispatcherTimer(); dTimer.Interval = TimeSpan.Zero; dTimer.Tick += DTimer_Tick; dTimer.Start(); // 获取 GridView 中的 ItemsWrapGrid 控件 _itemsWrapGrid1 = gridView1.ItemsPanelRoot as ItemsWrapGrid; _itemsWrapGrid2 = gridView2.ItemsPanelRoot as ItemsWrapGrid; // 获取 GridView 中的 ItemsWrapGrid 控件 // _itemsWrapGrid1 = Helper.GetVisualChild<ItemsWrapGrid>(gridView1); // _itemsWrapGrid2 = Helper.GetVisualChild<ItemsWrapGrid>(gridView2); } private void DTimer_Tick(object sender, object e) { lblMsg1.Text = "FirstCacheIndex: " + _itemsWrapGrid1.FirstCacheIndex.ToString(); lblMsg1.Text += Environment.NewLine; lblMsg1.Text += "FirstVisibleIndex: " + _itemsWrapGrid1.FirstVisibleIndex.ToString(); lblMsg1.Text += Environment.NewLine; lblMsg1.Text += "LastCacheIndex: " + _itemsWrapGrid1.LastCacheIndex.ToString(); lblMsg1.Text += Environment.NewLine; lblMsg1.Text += "LastVisibleIndex: " + _itemsWrapGrid1.LastVisibleIndex.ToString(); lblMsg1.Text += Environment.NewLine; lblMsg1.Text += "CacheLength: " + _itemsWrapGrid1.CacheLength.ToString(); } private void cmbGroupHeaderPlacement_SelectionChanged(object sender, SelectionChangedEventArgs e) { _itemsWrapGrid2.GroupHeaderPlacement = (GroupHeaderPlacement)Enum.Parse(typeof(GroupHeaderPlacement), (e.AddedItems[0] as ComboBoxItem).Content.ToString()); } // 解析 xml 数据 private List<NavigationModel> LoadData(XElement root) { if (root == null) return null; var items = from n in root.Elements("node") select new NavigationModel { Title = (string)n.Attribute("title"), Url = (string)n.Attribute("url"), Items = LoadData(n) }; return items.ToList(); } } }