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WPF:什么会导致 ComboBox 无法虚拟化?

转载 作者:行者123 更新时间:2023-12-04 20:15:48 25 4
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这是我的组合框。它似乎没有虚拟化,但我不明白为什么。您知道会导致这种情况的任何事情吗?

<ComboBox Grid.Row="0" Grid.Column="2" 
SelectedValuePath="PrimaryKey"
SelectedValue="{Binding CustomerKey}"
ItemsSource="{Binding CustomerCanidates}">
<ComboBox.ItemsPanel>
<ItemsPanelTemplate>
<VirtualizingStackPanel/>
</ItemsPanelTemplate>
</ComboBox.ItemsPanel>
</ComboBox>

最佳答案

检查应用于控件的样式。例如,Microsoft 的“ Shiny 蓝色”样式是这样定义的:

<ControlTemplate x:Key="ComboBoxTextBox" TargetType="{x:Type TextBox}">
<Border x:Name="PART_ContentHost" Focusable="False" Background="{TemplateBinding Background}"/>
</ControlTemplate>


<Style TargetType="{x:Type ComboBox}">
<Setter Property="SnapsToDevicePixels" Value="true"/>
<Setter Property="Template" Value="{DynamicResource ComboBoxTemplate}" />
</Style>

<ControlTemplate x:Key="ComboBoxTemplate" TargetType="{x:Type ComboBox}">
<Grid>
<ToggleButton Grid.Column="2" Template="{DynamicResource ComboBoxToggleButton}" x:Name="ToggleButton" Focusable="false" IsChecked="{Binding Path=IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" ClickMode="Press"/>
<ContentPresenter HorizontalAlignment="Left" Margin="3,3,23,3" x:Name="ContentSite" VerticalAlignment="Center" Content="{TemplateBinding SelectionBoxItem}" ContentTemplate="{TemplateBinding SelectionBoxItemTemplate}" ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}" IsHitTestVisible="False"/>

<TextBox Visibility="Hidden" Template="{DynamicResource ComboBoxTextBox}" HorizontalAlignment="Left" Margin="3,3,23,3" x:Name="PART_EditableTextBox" Style="{x:Null}" VerticalAlignment="Center" Focusable="True" Background="Transparent" IsReadOnly="{TemplateBinding IsReadOnly}"/>

<Popup IsOpen="{TemplateBinding IsDropDownOpen}" Placement="Bottom" x:Name="Popup" Focusable="False" AllowsTransparency="True" PopupAnimation="Slide">
<Grid MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{TemplateBinding ActualWidth}" x:Name="DropDown" SnapsToDevicePixels="True">
<Border x:Name="DropDownBorder" Background="{DynamicResource ShadeBrush}" BorderBrush="{DynamicResource SolidBorderBrush}" BorderThickness="1"/>
<ScrollViewer Margin="4,6,4,6" SnapsToDevicePixels="True" HorizontalScrollBarVisibility="Auto" VerticalScrollBarVisibility="Auto" CanContentScroll="True">

<StackPanel IsItemsHost="True" KeyboardNavigation.DirectionalNavigation="Contained"/>

</ScrollViewer>
</Grid>
</Popup>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="HasItems" Value="false">
<Setter Property="MinHeight" Value="95" TargetName="DropDownBorder"/>
</Trigger>
<Trigger Property="IsEnabled" Value="false">
<Setter Property="Foreground" Value="{DynamicResource DisabledForegroundBrush}"/>
</Trigger>
<Trigger Property="IsGrouping" Value="true">
<Setter Property="ScrollViewer.CanContentScroll" Value="false"/>
</Trigger>
<Trigger Property="AllowsTransparency" SourceName="Popup" Value="true">
<Setter Property="Margin" Value="0,0,0,0" TargetName="DropDownBorder"/>
<Setter Property="CornerRadius" TargetName="DropDownBorder" Value="3,3,3,3"/>
</Trigger>
<Trigger Property="IsEditable" Value="true">
<Setter Property="IsTabStop" Value="false"/>
<Setter Property="Visibility" Value="Visible" TargetName="PART_EditableTextBox"/>
<Setter Property="Visibility" Value="Hidden" TargetName="ContentSite"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>

仅仅将它从 StackPanel 更改为 VirtualizingStackPanel 就解决了我的问题。

关于WPF:什么会导致 ComboBox 无法虚拟化?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/3835472/

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