Xaml 使用依赖属性（UWP）从用户控件检索值_Xaml_Uwp_Uwp Xaml

Xaml 使用依赖属性（UWP）从用户控件检索值

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Xaml 使用依赖属性（UWP）从用户控件检索值,xaml,uwp,uwp-xaml,Xaml,Uwp,Uwp Xaml,我有一个这样的自定义用户控件 <Grid> <ListView x:Name="LView" SelectedIndex="{Binding SelectedIndex}" ItemsSource="{x:Bind ItemsSource, Mode=OneWay}" Width="{x:Bind Width}" Height="{x:Bind Height}" VerticalAlignment="Stretch" SelectionMode

我有一个这样的自定义用户控件

     <Grid>
        <ListView x:Name="LView" SelectedIndex="{Binding SelectedIndex}" ItemsSource="{x:Bind 
ItemsSource, Mode=OneWay}" Width="{x:Bind Width}" Height="{x:Bind Height}"  VerticalAlignment="Stretch"   SelectionMode="Multiple"  />
    </Grid>

        <local:CustomControl Grid.Column="0" Grid.Row="0"  Width="400"    Loaded="EditTextControl_Loaded"
                         x:Name="MultiCombo"     ></local:CustomControl>

在我的主页中，我像这样访问依赖属性

     <Grid>
        <ListView x:Name="LView" SelectedIndex="{Binding SelectedIndex}" ItemsSource="{x:Bind 
ItemsSource, Mode=OneWay}" Width="{x:Bind Width}" Height="{x:Bind Height}"  VerticalAlignment="Stretch"   SelectionMode="Multiple"  />
    </Grid>

        <local:CustomControl Grid.Column="0" Grid.Row="0"  Width="400"    Loaded="EditTextControl_Loaded"
                         x:Name="MultiCombo"     ></local:CustomControl>

但是，在selectedIndexChange（主页面中）上既没有触发事件，也没有在主页面上获取任何值。我怎样才能做到这一点？

注意：我已上载完整的代码

我认为问题在于您没有正确绑定所选的

索引。
您不需要绑定到self/列表视图的SelectedIndex
，而是需要将其绑定到CustomControl的SelectedIndex
DependencyProperty

<ListView ... SelectedIndex="{Binding
   Path=SelectedIndex,
   Mode=TwoWay,
   RelativeSource={RelativeSource
      Mode=FindAncestor,
      AncestorType={x:Type UserControl}}}" .../>



您可能需要根据需要将类型更改为CustomControl的类型（如果它不是UserControl
）。
我认为问题在于您没有正确绑定SelectedIndex。
您不需要绑定到self/列表视图的SelectedIndex
，而是需要将其绑定到CustomControl的SelectedIndex
DependencyProperty

<ListView ... SelectedIndex="{Binding
   Path=SelectedIndex,
   Mode=TwoWay,
   RelativeSource={RelativeSource
      Mode=FindAncestor,
      AncestorType={x:Type UserControl}}}" .../>



您可能需要根据需要将类型更改为CustomControl的类型（如果它不是UserControl
）。
在CustomControl页面中，当您在ListView中选择其他项时，将ListView的SelectedIndex属性与SelectedIndex依赖项属性绑定的模式是单向的，SelectedIndex dependency属性不会更改，因此主页面中multicmbo.SelectedIndex的值不会更改。在这种情况下，需要将模式设置为双向
CustomControl.xaml:
<ListView x:Name="LView" SelectedIndex="{x:Bind SelectedIndex,Mode=TwoWay}" ItemsSource="{x:Bind ItemsSource, Mode=OneWay}" Width="{x:Bind Width}" Height="{x:Bind Height}"  VerticalAlignment="Stretch" SelectionMode="Multiple"  />

public int MPSelectedIndex
{
    get { return (int)GetValue(MPSelectedIndexProperty); }
    set { SetValue(MPSelectedIndexProperty, value); }
}
public static readonly DependencyProperty MPSelectedIndexProperty =
        DependencyProperty.Register("MPSelectedIndex", typeof(int), typeof(MainPage), new PropertyMetadata(0, new PropertyChangedCallback(OnDataChanged)));

private static void OnDataChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
    MainPage currentPage = d as MainPage;
    int count = currentPage.MultiCombo.SelectedIndex;
}

<local:CustomControl Grid.Column="0" Grid.Row="0"  Width="400" Loaded="EditTextControl_Loaded" x:Name="MultiCombo"  SelectedIndex="{x:Bind MPSelectedIndex,Mode=TwoWay}" >
</local:CustomControl>

MainPage.xaml:
<ListView x:Name="LView" SelectedIndex="{x:Bind SelectedIndex,Mode=TwoWay}" ItemsSource="{x:Bind ItemsSource, Mode=OneWay}" Width="{x:Bind Width}" Height="{x:Bind Height}"  VerticalAlignment="Stretch" SelectionMode="Multiple"  />

public int MPSelectedIndex
{
    get { return (int)GetValue(MPSelectedIndexProperty); }
    set { SetValue(MPSelectedIndexProperty, value); }
}
public static readonly DependencyProperty MPSelectedIndexProperty =
        DependencyProperty.Register("MPSelectedIndex", typeof(int), typeof(MainPage), new PropertyMetadata(0, new PropertyChangedCallback(OnDataChanged)));

private static void OnDataChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
    MainPage currentPage = d as MainPage;
    int count = currentPage.MultiCombo.SelectedIndex;
}

<local:CustomControl Grid.Column="0" Grid.Row="0"  Width="400" Loaded="EditTextControl_Loaded" x:Name="MultiCombo"  SelectedIndex="{x:Bind MPSelectedIndex,Mode=TwoWay}" >
</local:CustomControl>



注意：
由于您将ListView的SelectionMode
设置为Multiple
，因此当您选择第一项时，SelectedIndex为0，然后您还选择了第二项，SelectedIndex仍然为0。只有在取消选择第一项时，SelectedIndex才会更改并触发该方法。
在CustomControl页面中，将ListView的SelectedIndex属性与SelectedIndex dependency属性绑定的模式是单向的，在ListView中选择其他项时，SelectedIndex dependency属性不会更改，因此主页中multicmbo.SelectedIndex的值不会更改。在这种情况下，需要将模式设置为双向
CustomControl.xaml:
<ListView x:Name="LView" SelectedIndex="{x:Bind SelectedIndex,Mode=TwoWay}" ItemsSource="{x:Bind ItemsSource, Mode=OneWay}" Width="{x:Bind Width}" Height="{x:Bind Height}"  VerticalAlignment="Stretch" SelectionMode="Multiple"  />

public int MPSelectedIndex
{
    get { return (int)GetValue(MPSelectedIndexProperty); }
    set { SetValue(MPSelectedIndexProperty, value); }
}
public static readonly DependencyProperty MPSelectedIndexProperty =
        DependencyProperty.Register("MPSelectedIndex", typeof(int), typeof(MainPage), new PropertyMetadata(0, new PropertyChangedCallback(OnDataChanged)));

private static void OnDataChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
    MainPage currentPage = d as MainPage;
    int count = currentPage.MultiCombo.SelectedIndex;
}

<local:CustomControl Grid.Column="0" Grid.Row="0"  Width="400" Loaded="EditTextControl_Loaded" x:Name="MultiCombo"  SelectedIndex="{x:Bind MPSelectedIndex,Mode=TwoWay}" >
</local:CustomControl>

MainPage.xaml:
<ListView x:Name="LView" SelectedIndex="{x:Bind SelectedIndex,Mode=TwoWay}" ItemsSource="{x:Bind ItemsSource, Mode=OneWay}" Width="{x:Bind Width}" Height="{x:Bind Height}"  VerticalAlignment="Stretch" SelectionMode="Multiple"  />

public int MPSelectedIndex
{
    get { return (int)GetValue(MPSelectedIndexProperty); }
    set { SetValue(MPSelectedIndexProperty, value); }
}
public static readonly DependencyProperty MPSelectedIndexProperty =
        DependencyProperty.Register("MPSelectedIndex", typeof(int), typeof(MainPage), new PropertyMetadata(0, new PropertyChangedCallback(OnDataChanged)));

private static void OnDataChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
    MainPage currentPage = d as MainPage;
    int count = currentPage.MultiCombo.SelectedIndex;
}

<local:CustomControl Grid.Column="0" Grid.Row="0"  Width="400" Loaded="EditTextControl_Loaded" x:Name="MultiCombo"  SelectedIndex="{x:Bind MPSelectedIndex,Mode=TwoWay}" >
</local:CustomControl>



注意：
由于您将ListView的SelectionMode
设置为Multiple
，因此当您选择第一项时，SelectedIndex为0，然后您还选择了第二项，SelectedIndex仍然为0。只有在取消选择第一项时，SelectedIndex才会更改并触发该方法