使用 DataTrigger 显示控件的 WPF 在 TabOrder 中跳过它

WPF showing control with DataTrigger skips it in TabOrder

我想在前一个 TextBox 的值不是 0.00(零)时显示 'additional details' 文本框。使用 DataTriggers 可以轻松完成此操作:

<TextBox Name="FirstTB" Text="{Binding Amount, StringFormat=F2}"/><!--when this TB is not 0-->
<TextBox Name="SecondTB"> <!--show this TB-->
    <TextBox.Style>
        <Style TargetType="{x:Type TextBox}">
            <Style.Triggers>
                <DataTrigger Binding="{Binding Amount}" Value="0">
                    <Setter Property="Visibility" Value="Hidden"/>
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </TextBox.Style>
</TextBox>
<TextBox Name="ThirdTB"/>

但是,当将 FirstTB 的值更改为 <> 0 并按下 Tab 时,焦点会跳转到 ThirdTB 而不是 SecondTB(即使 SecondTB 由于 DataTrigger 现在可见)。我该如何解决这个问题?


遗憾的是,UpdateSourceTrigger=PropertyChanged 似乎不是一个选项,因为它会干扰 StringFormats - 当您编辑值时它会提供糟糕的用户体验,carret 由于不断字符串格式评估。上面示例中使用的视图模型:

public class MyVM : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    private double _amount;
    public double Amount
    {
        get { return _amount; }
        set
        {
            _amount = value;
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(Amount)));
        }
    }

}

也许是一个愚蠢的变通办法。但这将完成工作:

查看:

<TextBox Name="SecondTB" IsVisibleChanged="SecondTB_OnIsVisibleChanged">
     <!--show this TB-->
     <TextBox.Style>
         <Style TargetType="{x:Type TextBox}">
              <Style.Triggers>
                    <DataTrigger Binding="{Binding Amount, Mode=OneWay}" Value="0">
                         <Setter Property="Visibility" Value="Collapsed"/>
                    </DataTrigger>
              </Style.Triggers>
         </Style>
    </TextBox.Style>
</TextBox>

C#:

private void SecondTB_OnIsVisibleChanged(object sender, DependencyPropertyChangedEventArgs e)
{
    if (((bool) e.NewValue))
    {
        if(!(sender is TextBox txbx)) return;
        ThirdTB.GotFocus += ThirdTbOnGotFocus;
    }
}

private void ThirdTbOnGotFocus(object sender, RoutedEventArgs e)
{
    SecondTB.Focus();
    ThirdTB.GotFocus -= ThirdTbOnGotFocus;
}

如果你使用 IValueConverter,你会得到一个非常优雅的方式来解决你的问题。每次更改值时,都会调用逻辑。


public class IsZeroToHiddenConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value is double d && d == 0)
            return Visibility.Hidden;
        return Visibility.Visible;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

您还可以尝试并添加 ConverterParameter 来决定您是想要 Collapsed 还是 Hidden 行为。

用法


<Grid>
    <Grid.Resources>
        <local:IsZeroToHiddenConverter x:Key="IsZeroToHiddenConverter"/>
    </Grid.Resources>
    <Grid VerticalAlignment="Center" HorizontalAlignment="Center">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="Auto"/>
        </Grid.RowDefinitions>
        <TextBox x:Name="Tb1" Grid.Row="0" Width="100" Margin="5" Text="{Binding Path=Amount, StringFormat=F2, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"/>
        <TextBox x:Name="Tb2" Grid.Row="1" Width="100" Margin="5" Visibility="{Binding Path=Amount, Converter={StaticResource IsZeroToHiddenConverter}}"/>
        <TextBox x:Name="Tb3" Grid.Row="2" Width="100" Margin="5"/>
    </Grid>
</Grid>

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