我已阅读@ How to stop Wpf Tabcontrol to unload Visual tree on Tab change的帖子，但我无法使其发挥作用，我一定错过了一些东西。请帮忙。谢谢
中的类TabControlEx<Window x:Class="MyMainwindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:sharedC="clr-namespace:myShared.Converter;assembly=myShared"
xmlns:mainTab="clr-namespace:MyWPFLib.View" Title="{Binding Title}"
Height="600" Width="850" Top="223" Left="164" ResizeMode="CanResize" Closing="WindowClosing"
WindowStyle="ToolWindow">
<Grid>
<mainTab:TabControlEx IsSynchronizedWithCurrentItem="True"
Grid.Row="0"
Margin="10 0 5 5"
x:Name="MainTabRegion"
TabStripPlacement="Top"
SelectedIndex="{Binding Tabs.SelectedIndex}"
ItemsSource="{Binding Tabs.TabItems}"
>
<TabControl.ItemContainerStyle>
<Style TargetType="{x:Type TabItem}">
<Setter Property="Header">
<Setter.Value>
<Binding Path="Header"/>
</Setter.Value>
</Setter>
<Setter Property="Visibility"
Value="{Binding IsVisible, Mode=OneWay, Converter={StaticResource boolToVis}}"/>
</Style>
</TabControl.ItemContainerStyle>
</mainTab:TabControlEx>
</Grid>
</Window>
Datasource for the maintab is Tabs.TabItems
public ObservableCollection<ITabControl> TabItems
{
get
{
return _items;
}
}
每个TabItem都是用
构建的<DataTemplate DataType="{x:Type vm:Item1ViewModel}">
<vw:View1 />
</DataTemplate>
答案 0 :(得分：5)
我一直使用该链接中的代码而没有任何问题，尽管我注意到自从我第一次获得代码以来网站已经发生了变化。您可能想要检查我拥有的内容与网站内容之间的任何代码差异。
以下是我们在更改网站之前获得的代码：
// Extended TabControl which saves the displayed item so you don't get the performance hit of
// unloading and reloading the VisualTree when switching tabs
// Obtained from http://www.pluralsight-training.net/community/blogs/eburke/archive/2009/04/30/keeping-the-wpf-tab-control-from-destroying-its-children.aspx
// and made a some modifications so it reuses a TabItem's ContentPresenter when doing drag/drop operations
[TemplatePart(Name = "PART_ItemsHolder", Type = typeof(Panel))]
public class TabControlEx : System.Windows.Controls.TabControl
{
// Holds all items, but only marks the current tab's item as visible
private Panel _itemsHolder = null;
// Temporaily holds deleted item in case this was a drag/drop operation
private object _deletedObject = null;
public TabControlEx()
: base()
{
// this is necessary so that we get the initial databound selected item
this.ItemContainerGenerator.StatusChanged += ItemContainerGenerator_StatusChanged;
}
/// <summary>
/// if containers are done, generate the selected item
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
void ItemContainerGenerator_StatusChanged(object sender, EventArgs e)
{
if (this.ItemContainerGenerator.Status == GeneratorStatus.ContainersGenerated)
{
this.ItemContainerGenerator.StatusChanged -= ItemContainerGenerator_StatusChanged;
UpdateSelectedItem();
}
}
/// <summary>
/// get the ItemsHolder and generate any children
/// </summary>
public override void OnApplyTemplate()
{
base.OnApplyTemplate();
_itemsHolder = GetTemplateChild("PART_ItemsHolder") as Panel;
UpdateSelectedItem();
}
/// <summary>
/// when the items change we remove any generated panel children and add any new ones as necessary
/// </summary>
/// <param name="e"></param>
protected override void OnItemsChanged(NotifyCollectionChangedEventArgs e)
{
base.OnItemsChanged(e);
if (_itemsHolder == null)
{
return;
}
switch (e.Action)
{
case NotifyCollectionChangedAction.Reset:
_itemsHolder.Children.Clear();
if (base.Items.Count > 0)
{
base.SelectedItem = base.Items[0];
UpdateSelectedItem();
}
break;
case NotifyCollectionChangedAction.Add:
case NotifyCollectionChangedAction.Remove:
// Search for recently deleted items caused by a Drag/Drop operation
if (e.NewItems != null && _deletedObject != null)
{
foreach (var item in e.NewItems)
{
if (_deletedObject == item)
{
// If the new item is the same as the recently deleted one (i.e. a drag/drop event)
// then cancel the deletion and reuse the ContentPresenter so it doesn't have to be
// redrawn. We do need to link the presenter to the new item though (using the Tag)
ContentPresenter cp = FindChildContentPresenter(_deletedObject);
if (cp != null)
{
int index = _itemsHolder.Children.IndexOf(cp);
(_itemsHolder.Children[index] as ContentPresenter).Tag =
(item is TabItem) ? item : (this.ItemContainerGenerator.ContainerFromItem(item));
}
_deletedObject = null;
}
}
}
if (e.OldItems != null)
{
foreach (var item in e.OldItems)
{
_deletedObject = item;
// We want to run this at a slightly later priority in case this
// is a drag/drop operation so that we can reuse the template
this.Dispatcher.BeginInvoke(DispatcherPriority.DataBind,
new Action(delegate()
{
if (_deletedObject != null)
{
ContentPresenter cp = FindChildContentPresenter(_deletedObject);
if (cp != null)
{
this._itemsHolder.Children.Remove(cp);
}
}
}
));
}
}
UpdateSelectedItem();
break;
case NotifyCollectionChangedAction.Replace:
throw new NotImplementedException("Replace not implemented yet");
}
}
/// <summary>
/// update the visible child in the ItemsHolder
/// </summary>
/// <param name="e"></param>
protected override void OnSelectionChanged(SelectionChangedEventArgs e)
{
base.OnSelectionChanged(e);
UpdateSelectedItem();
}
/// <summary>
/// generate a ContentPresenter for the selected item
/// </summary>
void UpdateSelectedItem()
{
if (_itemsHolder == null)
{
return;
}
// generate a ContentPresenter if necessary
TabItem item = GetSelectedTabItem();
if (item != null)
{
CreateChildContentPresenter(item);
}
// show the right child
foreach (ContentPresenter child in _itemsHolder.Children)
{
child.Visibility = ((child.Tag as TabItem).IsSelected) ? Visibility.Visible : Visibility.Collapsed;
}
}
/// <summary>
/// create the child ContentPresenter for the given item (could be data or a TabItem)
/// </summary>
/// <param name="item"></param>
/// <returns></returns>
ContentPresenter CreateChildContentPresenter(object item)
{
if (item == null)
{
return null;
}
ContentPresenter cp = FindChildContentPresenter(item);
if (cp != null)
{
return cp;
}
// the actual child to be added. cp.Tag is a reference to the TabItem
cp = new ContentPresenter();
cp.Content = (item is TabItem) ? (item as TabItem).Content : item;
cp.ContentTemplate = this.SelectedContentTemplate;
cp.ContentTemplateSelector = this.SelectedContentTemplateSelector;
cp.ContentStringFormat = this.SelectedContentStringFormat;
cp.Visibility = Visibility.Collapsed;
cp.Tag = (item is TabItem) ? item : (this.ItemContainerGenerator.ContainerFromItem(item));
_itemsHolder.Children.Add(cp);
return cp;
}
/// <summary>
/// Find the CP for the given object. data could be a TabItem or a piece of data
/// </summary>
/// <param name="data"></param>
/// <returns></returns>
ContentPresenter FindChildContentPresenter(object data)
{
if (data is TabItem)
{
data = (data as TabItem).Content;
}
if (data == null)
{
return null;
}
if (_itemsHolder == null)
{
return null;
}
foreach (ContentPresenter cp in _itemsHolder.Children)
{
if (cp.Content == data)
{
return cp;
}
}
return null;
}
/// <summary>
/// copied from TabControl; wish it were protected in that class instead of private
/// </summary>
/// <returns></returns>
protected TabItem GetSelectedTabItem()
{
object selectedItem = base.SelectedItem;
if (selectedItem == null)
{
return null;
}
if (_deletedObject == selectedItem)
{
}
TabItem item = selectedItem as TabItem;
if (item == null)
{
item = base.ItemContainerGenerator.ContainerFromIndex(base.SelectedIndex) as TabItem;
}
return item;
}
}
我确实对原始代码进行了一些更改，因为我拖放了标签，并且在删除项目并重新添加标签时不想重新创建标签，但老实说它已经很久了我忘记了什么部分是我的，什么不是。
我做了一个快速测试来仔细检查，是的，它确实保留了您的非约束值，例如选定值或扩展值。
修改
在回复下面的评论时，将DataTemplates放在Resources某处，定义哪个UserControl用于每个Tab。当TabControl尝试绘制每个Tab的内容时，它将使用您为该数据类型定义的任何DataTemplate
<Window.Resources>
<DataTemplate TargetType="{x:Type local:TabAViewModel}">
<local:TabAView />
</DataTemplate>
<DataTemplate TargetType="{x:Type local:TabBViewModel}">
<local:TabBView />
</DataTemplate>
</Window.Resources>
<TabControl ItemsSource="{Binding TabItems}">
<TabControl.ItemContainerStyle>
<Style TargetType="{x:Type TabItem}">
<Setter Property="Header" Value="{Binding Header}" />
</Style>
</TabControl.ItemContainerStyle>
</TabControl>
...视图模型
public MyViewModelConstructor()
{
TabItems.Add(New TabAViewModel { Header = "Tab A" });
TabItems.Add(New TabBViewModel { Header = "Tab B" });
}
编辑＃2
文字XAML，如您所要求的那样
<local:TabControlEx>
<TabItem Header="Test1">
<DataGrid ItemsSource="{Binding Test}">
<DataGrid.Columns>
<DataGridTextColumn Binding="{Binding TestValue}" Header="Test" />
</DataGrid.Columns>
</DataGrid>
</TabItem>
<TabItem Header="Test2">
<DataGrid ItemsSource="{Binding Test}">
<DataGrid.Columns>
<DataGridTextColumn Binding="{Binding TestValue}" Header="Test" />
</DataGrid.Columns>
</DataGrid>
</TabItem>
</local:TabControlEx>
答案 1 :(得分：2)
我放弃了解决方法，它只是在我的情况下不起作用。我购买了第三方WPF库（DevExpress WPF）来解决这个问题。感谢