WPF：为什么使用多个 WindowsFormsHost 时 UI 会变得缓慢？
我有一个数据绑定的 TreeView，其项目的数据模板中有一个 WindowsFormsHost 。 TreeView 中的项目越多，其中的 WindowsFormsHost 就越多，UI 就会变得越慢。
TreeView 位于 TabItem 中，而 TabItem 本身位于 TabControl 中。每当选择 TabItem 时（即当我从另一个 TabItem 切换到带有 TreeView 的 TabItem 时），这种迟缓现象最为明显。
为了简化，我使用 ListBox 而不是 TreeView 制作了一个更简单的应用程序：
<Window x:Class="WpfApplication1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<TabControl>
<TabItem Header="Tab 1">
<StackPanel>
<Button Content="Add 50 WindowsFormsHost controls"
Click="Button_Click" />
<ListBox Name="lst" Height="300">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel>
<TextBlock Text="{Binding Path=Bar}" />
<WindowsFormsHost />
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</StackPanel>
</TabItem>
<TabItem Header="Tab 2" />
</TabControl>
</Window>
在表单代码中使用此内容：
class Foo { public string Bar { get { return DateTime.Now.Ticks.ToString(); } } }
void Button_Click(object sender, RoutedEventArgs e)
{
if (lst.ItemsSource == null)
lst.ItemsSource = new ObservableCollection<Foo>();
for (int j = 0; j < 50; j++)
(lst.ItemsSource as IList<Foo>).Add(new Foo());
}
单击按钮后，滚动 ListBox 的内容变得不那么流畅，并且切换回选项卡 1 时会出现延迟。
任何想法为什么会发生这种情况，以及是否有什么办法可以解决？
I have a data-bound TreeView with a WindowsFormsHost in the data template of its items. The more items in the TreeView, and so the more WindowsFormsHost in it, the slower the UI becomes.
The TreeView is in a TabItem, itself in a TabControl. The sluggishness is most obvious whenever the TabItem is selected (ie when I switch from another TabItem to the TabItem with the TreeView).
To simplify, I made a simpler app with a ListBox instead of a TreeView:
<Window x:Class="WpfApplication1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<TabControl>
<TabItem Header="Tab 1">
<StackPanel>
<Button Content="Add 50 WindowsFormsHost controls"
Click="Button_Click" />
<ListBox Name="lst" Height="300">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel>
<TextBlock Text="{Binding Path=Bar}" />
<WindowsFormsHost />
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</StackPanel>
</TabItem>
<TabItem Header="Tab 2" />
</TabControl>
</Window>
With this in the form's code:
class Foo { public string Bar { get { return DateTime.Now.Ticks.ToString(); } } }
void Button_Click(object sender, RoutedEventArgs e)
{
if (lst.ItemsSource == null)
lst.ItemsSource = new ObservableCollection<Foo>();
for (int j = 0; j < 50; j++)
(lst.ItemsSource as IList<Foo>).Add(new Foo());
}
After clicking the button, scrolling the ListBox's content becomes less fluid, and there is a delay when switching back to Tab 1.
Any ideas on why this is happening, and on if there is anything to do about it?
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为什么不能在单个 WindowsFormsHost 中托管一个具有上述项目的 WinForm ListBox，而不是在 WPF ListBox 的项目中托管多个 WindowsFormsHost？这不仅使滚动变得容易（由于完全在 WinForms UI 上下文中），而且还使您的 WPF 应用程序内存高效（由于单个 WindowsFormsHost）。
如果这不是您想要的，那么请尝试松开列表框项目面板的虚拟化（默认情况下是 VirtualizedStackPanel）。
让我知道这是否有帮助？
Instead of hosting multiple WindowsFormsHost in a WPF ListBox's items, why cant you host one WinForm ListBox having above items in a single WindowsFormsHost? This would not only make the scrolling easy (due to entirely in WinForms UI context) but also make your WPF app memory efficient (due to single WindowsFormsHost).
If this is not what you are for, then try to loose the Virtualisation of your ListBox's Items Panel (which by default is a VirtualizedStackPanel).
Let me know if this helps?