3/29/2024 0 Comments Wpf dynamic treeview example![]() ![]() When a user clicks a TreeViewItem control to select it, the Selected event occurs, and its IsSelected property is set to true. If a TreeViewItem is not visible or partially visible, the TreeView scrolls to make it visible. When the BringIntoView method is called on a TreeViewItem control, the TreeViewItem and its parent TreeViewItem controls expand. When this property changes, an Expanded or Collapsed event occurs. ![]() You can also expand or collapse a TreeViewItem without any direct user action by setting the IsExpanded property to true (expand) or false (collapse). If the user expands a TreeViewItem, the IsExpanded property is set to true. ![]() If an item is not a TreeViewItem control, it is automatically enclosed by a TreeViewItem control when the TreeView control is displayed. For more information and an example, see Use SelectedValue, SelectedValuePath, and SelectedItem. To define the layout of a TreeViewItem control, you can also use HierarchicalDataTemplate objects. You can also specify an ItemsSource as a data source and then specify a HeaderTemplate and ItemTemplate to define the TreeViewItem content. The previous illustration demonstrates this method. If you are defining a TreeView by using Extensible Application Markup Language (XAML), you can explicitly define the Header content of a TreeViewItem control and the items that make up its collection. A TreeViewItem control is a HeaderedItemsControl that has a Header and an Items collection. The TreeView control contains a hierarchy of TreeViewItem controls. The following example creates a TreeView. TreeView is an ItemsControl that nests the items by using TreeViewItem controls. This topic introduces the TreeView and TreeViewItem controls, and provides simple examples of their use. SecondLevelItems.Add("Second Level " & i.The TreeView control provides a way to display information in a hierarchical structure by using collapsible nodes. Level2Items = New ObservableCollection(Of String)() Public ReadOnly Property SecondLevelItems() As ObservableCollection(Of String) Private level2Items As ObservableCollection(Of String) Item.TopLevelName = "item " & i.ToString() Inherits ObservableCollection(Of ItemsForTreeView) SecondLevelItems.Add("Second Level " + i.ToString()) Level2Items ?= new ObservableCollection() Public ObservableCollection SecondLevelItems public class TreeViewData : ObservableCollection The following example shows the data that the previous example uses. The following example creates a TreeView that sets the VirtualizingStackPanel.IsVirtualizing attached property to true and the VirtualizingStackPanel.VirtualizationMode attached property to VirtualizationMode.Recycling to optimize its performance. ![]() You can improve the performance of the TreeView when the user scrolls by setting the VirtualizingStackPanel.VirtualizationMode attached property to VirtualizationMode.Recycling. The UI might also be slow to react when a user scrolls the TreeView by using the mouse wheel or dragging the thumb of a scrollbar. You can improve the load time by setting the VirtualizingStackPanel.IsVirtualizing attached property to true. If a TreeView contains many items, the amount of time it takes to load may cause a significant delay in the user interface. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |