组合框上的绑定错误 4

Question

找不到原因。代码：

<ComboBox OverridesDefaultStyle="True" MinWidth="70" MinHeight="20"
            IsSynchronizedWithCurrentItem="True" ScrollViewer.CanContentScroll="True"
            ToolTip="{Binding Text, Mode=TwoWay, ElementName=UserControl}"
            IsEditable="{Binding IsEditable, Mode=OneWay, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=local:SmartMultiTypeListView}}"
            ItemsSource="{Binding ElementName=UserControl, Path=ItemsSource}"
            DataContext="{Binding ElementName=UserControl, Path=DataContext}"
            IsEnabledChanged="OnIsEnabledChanged">
  <ComboBox.ItemContainerStyle>
    <Style TargetType="{x:Type ComboBoxItem}">
      <Setter Property="HorizontalContentAlignment" Value="Left" />
      <Setter Property="VerticalContentAlignment" Value="Center" />
    </Style>
  </ComboBox.ItemContainerStyle>
</ComboBox>

已启用：

/// <summary>
/// Used to handle when the combobox is enabled/disabled
/// </summary>
private void OnIsEnabledChanged (object Sender, DependencyPropertyChangedEventArgs E)
  {
  if ((bool)E.NewValue == true)
    {
    ComboBox CBox = Sender as ComboBox;
    if (CBox != null)
      {
      IEnumerable LastBinding = CBox.ItemsSource; // Store old binding
      CBox.ItemsSource = null; // Forces refresh/rebinding
      CBox.ItemsSource = LastBinding; // Reset binding by rebinding the old value
      }
    }
  }

看起来相当无害，但我在构建过程中收到错误号 4，一个是 HorizontalContentAlignment，一个是 VerticalContentAlignment：

System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''. BindingExpression:Path=HorizontalContentAlignment; DataItem=null; target element is 'ListViewItem' (Name=''); target property is 'HorizontalContentAlignment' (type 'HorizontalAlignment')

找不到任何适用于 SO 的解决方案。我尝试过覆盖ListViewItem、ComboBoxItem 和ListBoxItem 样式，但它不起作用。错误本身只发生 20% 的时间，这使得跟踪变得更加困难。有时，错误似乎很少发生在程序结束时（很多次，20 多次）。以上是我可以从UserControl中提取的MVCE。

是什么原因造成的？

编辑

完整的 XAML：

  <ComboBox OverridesDefaultStyle="True" MinWidth="70" MinHeight="20"
            IsSynchronizedWithCurrentItem="True" ScrollViewer.CanContentScroll="True"
            ToolTip="{Binding Text, Mode=TwoWay, ElementName=UserControl}"
            IsEditable="{Binding IsEditable, Mode=OneWay, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=local:SmartMultiTypeListView}}"
            ItemsSource="{Binding ElementName=UserControl, Path=ItemsSource}"
            DataContext="{Binding ElementName=UserControl, Path=DataContext}"
            HorizontalContentAlignment="Left"
            VerticalContentAlignment="Center"
            IsEnabledChanged="OnIsEnabledChanged">
    <ComboBox.ItemContainerStyle>
      <Style TargetType="{x:Type ComboBoxItem}">
        <Setter Property="HorizontalAlignment" Value="Left" />
        <Setter Property="VerticalAlignment" Value="Center" />
      </Style>
    </ComboBox.ItemContainerStyle>

    <ComboBox.ItemTemplate>
      <HierarchicalDataTemplate>
        <CheckBox Content="{Binding Name}" Margin="2" IsChecked="{Binding IsChecked, Mode=TwoWay}"
                  IsEnabled="{Binding IsEnabled}" Tag="{RelativeSource FindAncestor, AncestorType={x:Type ComboBox}}" />
      </HierarchicalDataTemplate>
    </ComboBox.ItemTemplate>

    <ComboBox.Template>
      <ControlTemplate TargetType="ComboBox">
        <Grid>
          <ToggleButton Grid.Column="2" Focusable="False"
                        IsChecked="{Binding Path=IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}"
                        ClickMode="Press"/>

          <ContentPresenter x:Name="Presenter" IsHitTestVisible="False" Margin="3, 3, 23, 3" VerticalAlignment="Center" 
                            HorizontalAlignment="Left" >
            <ContentPresenter.Content>
              <TextBlock TextTrimming="CharacterEllipsis" Foreground="Black"
                         Text="{Binding Path=Text, Mode=TwoWay, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=UserControl}}" />
            </ContentPresenter.Content>
          </ContentPresenter>

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

          <Popup x:Name="Popup" Placement="Bottom" IsOpen="{TemplateBinding IsDropDownOpen}" AllowsTransparency="True"
                 Focusable="False" PopupAnimation="None">
            <Grid SnapsToDevicePixels="True" MinWidth="{TemplateBinding ActualWidth}" MaxHeight="{TemplateBinding MaxDropDownHeight}">
              <Border x:Name="DropDownBorder" Background="{StaticResource WindowBackgroundBrush}" BorderThickness="1" 
                      BorderBrush="#444" />
              <ScrollViewer Margin="4, 6, 4, 6" SnapsToDevicePixels="True" DataContext="{Binding}">
                <StackPanel IsItemsHost="True" KeyboardNavigation.DirectionalNavigation="Contained" />
              </ScrollViewer>
            </Grid>
          </Popup>
        </Grid>

        <ControlTemplate.Triggers>
          <Trigger Property="HasItems" Value="false">
            <Setter TargetName="DropDownBorder" Property="MinHeight" Value="95" />
          </Trigger>
          <Trigger Property="IsEnabled" Value="false">
            <Setter Property="Foreground" Value="{StaticResource DisabledForegroundBrush}" />
          </Trigger>
          <Trigger Property="IsGrouping" Value="true">
            <Setter Property="ScrollViewer.CanContentScroll" Value="false" />
          </Trigger>
          <Trigger SourceName="Popup" Property="Popup.AllowsTransparency" Value="true">
            <Setter TargetName="DropDownBorder" Property="Margin" Value="0, 2, 0, 0" />
          </Trigger>
          <Trigger Property="IsEditable" Value="False">
            <Setter Property="IsEnabled" Value="False" />
            <Setter Property="IsTabStop" Value="False" />
            <Setter TargetName="EditableTextBox" Property="Visibility" Value="Visible" />
            <Setter TargetName="Presenter" Property="Visibility" Value="Hidden" />
          </Trigger>
        </ControlTemplate.Triggers>
      </ControlTemplate>
    </ComboBox.Template>
  </ComboBox>

编辑

最新错误：

System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''. BindingExpression:Path=HorizontalContentAlignment; DataItem=null; target element is 'ListViewItem' (Name=''); target property is 'HorizontalContentAlignment' (type 'HorizontalAlignment')

System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''. BindingExpression:Path=VerticalContentAlignment; DataItem=null; target element is 'ListViewItem' (Name=''); target property is 'VerticalContentAlignment' (type 'VerticalAlignment')

System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''. BindingExpression:Path=HorizontalContentAlignment; DataItem=null; target element is 'ListBoxItem' (Name=''); target property is 'HorizontalContentAlignment' (type 'HorizontalAlignment')

System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''. BindingExpression:Path=VerticalContentAlignment; DataItem=null; target element is 'ListBoxItem' (Name=''); target property is 'VerticalContentAlignment' (type 'VerticalAlignment')

我省略了重复的错误（我得到了大约 20 个，都与上面的后 2 个相似）。

Answer 1

HorizontalContentAlignment 和 VerticalContentAlignment 属性在 ComboBoxItem 或 ListViewItem 上不存在。你有两个选择：

1. 在ComboBox 上设置对齐

尝试删除这些：

<Setter Property="HorizontalContentAlignment" Value="Left" />
<Setter Property="VerticalContentAlignment" Value="Center" />

并将以下内容放入 ComboBox 元素中（例如）：

<ComboBox OverridesDefaultStyle="True" MinWidth="70" MinHeight="20"
        IsSynchronizedWithCurrentItem="True" ScrollViewer.CanContentScroll="True"
        ToolTip="{Binding Text, Mode=TwoWay, ElementName=UserControl}"
        IsEditable="{Binding IsEditable, Mode=OneWay, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=local:SmartMultiTypeListView}}"
        ItemsSource="{Binding ElementName=UserControl, Path=ItemsSource}"
        DataContext="{Binding ElementName=UserControl, Path=DataContext}"
        IsEnabledChanged="OnIsEnabledChanged"

        HorizontalContentAlignment="Left"
        VerticalContentAlignment="Center">

1. 按照您原来的方法设置对齐方式：

改变这个：

<Setter Property="HorizontalContentAlignment" Value="Left" />
<Setter Property="VerticalContentAlignment" Value="Center" />

收件人：

<Setter Property="HorizontalAlignment" Value="Left" />
<Setter Property="VerticalAlignment" Value="Center" />