如何設置綁定到文本框的標籤的可見性？

我有三個TEXTBOX綁定到LABEL。當我在TEXTBOX中鍵入內容時，TextBox文本值被設置爲Label。 問題是我想設置可見性的標籤，當文本框爲空，反之亦然。如何使用WPF中的可見性轉換？如何設置綁定到文本框的標籤的可見性？

在.XAML文件

：

<TextBox Name="txtEmail1" Grid.Column="1" Grid.Row="0" Text="Email" HorizontalAlignment="Stretch" Margin="2" VerticalAlignment="Stretch"/> 
<TextBox Name="txtEmail2" Grid.Column="1" Grid.Row="0" Text="Email2" Visibility="Collapsed" Margin="2" HorizontalAlignment="Stretch" VerticalAlignment="Stretch"/> 
<TextBox Name="txtEmail3" Grid.Column="1" Grid.Row="0" Text="Email3" Visibility="Collapsed" Margin="2" HorizontalAlignment="Stretch" VerticalAlignment="Stretch"/> 

<Label Name="lblContactEmail1" Content="{Binding Path=Text, ElementName=txtEmail1, Mode=OneWay, UpdateSourceTrigger=PropertyChanged}" VerticalAlignment="Stretch" HorizontalAlignment="Stretch"/> 
<Label Name="lblContactEmail2" Content="{Binding Path=Text, ElementName=txtEmail2, Mode=OneWay, UpdateSourceTrigger=PropertyChanged}" VerticalAlignment="Stretch" HorizontalAlignment="Stretch"/> 
<Label Name="lblContactEmail3" Content="{Binding Path=Text, ElementName=txtEmail3, Mode=OneWay, UpdateSourceTrigger=PropertyChanged}" VerticalAlignment="Stretch" HorizontalAlignment="Stretch"/>

我曾嘗試爲：使用下面類StringToVisibilityConverter.cs

<UserControl xmlns:dxe="http://schemas.devexpress.com/winfx/2008/xaml/editors" x:Class="XtremeProcurementWPF.UserControls.usContactForm" 
      xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
      xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
      xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
      xmlns:cv="clr-namespace:MyWPF" 
      mc:Ignorable="d"> 
<UserControl.Resources> 
     <cv:StringToVisibilityConverter x:Key="visibilityconverter" /> 
    </UserControl.Resources> 
<Grid> 
<TextBox Name="txtEmail1" Grid.Column="1" Grid.Row="0" Text="Email" HorizontalAlignment="Stretch" Margin="2" VerticalAlignment="Stretch" /> 
    <Label Name="lblContactEmail1" Content="{Binding Path=Text, ElementName=txtEmail1, Mode=OneWay, UpdateSourceTrigger=PropertyChanged,Converter={StaticResource visibilityconverter}}" VerticalAlignment="Stretch" HorizontalAlignment="Stretch"/> 
</Grid> 
</UserControl>

問題：它顯示的文本標籤爲「可見」，而不是在文本框中輸入的確切文本。

幫助讚賞！謝謝！在你的資源

public class StringToVisibilityConverter: IValueConverter 
{ 
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) 
    { 
     var s = value as string; 

     if (string.IsNullOrWhiteSpace(s)) 
      return Visibility.Collapsed; 

     return Visibility.Visible; 
    } 

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

現在的地方您註冊轉換器：

來源

2013-06-25 SHEKHAR SHETE

仔細看看我的例子。你是**不是**應該使用轉換器作爲'Content'屬性，但是對於'Visibility'屬性，如我的示例所示。內容應該保留原來的樣子。 –

檢查我對我的回答所做的修改。 –

創建您自己的實現IValueConverter接口

<converters:StringToVisibilityConverter x:Key="StringToVisibilityConverter" />

最後，您使用轉換器的元素，像這樣：

<Label Name="lblContactEmail3" 
Visibility="{Binding Path=Text, ElementName=txtEmail3, Converter={StaticResource StringToVisibilityConverter}}" ... />

編輯：

這裏是爲Label的完整代碼：

<Label Name="lblContactEmail1" Content="{Binding Path=Text, ElementName=txtEmail1, Mode=OneWay, UpdateSourceTrigger=PropertyChanged}" Visibility="{Binding Path=Text, ElementName=txtEmail1, Converter={StaticResource visibilityconverter}}" VerticalAlignment="Stretch" HorizontalAlignment="Stretch"/>

來源

2013-06-25 08:56:50

對不起@Klaus！但是如何使用它？我是wpf的新手！ –

我已經更新了我的答案。 –

尚未發佈！請檢查以上我已編輯！ –

你可以使用一個DataTrigger這樣的：

<StackPanel> 
     <StackPanel.Resources> 
     <Style TargetType="{x:Type Label}"> 
      <Style.Triggers> 
       <DataTrigger Binding="{Binding ElementName=txtEmail1, Path=Text}" Value=""> 
        <Setter Property="Visibility" Value="Collapsed"/> 
       </DataTrigger> 
      </Style.Triggers> 
     </Style> 
     </StackPanel.Resources> 

     <TextBox Name="txtEmail1" Text="Email" /> 
     <Label Name="lblContactEmail1" Background="Yellow" Content="{Binding Path=Text, ElementName=txtEmail1}" /> 
    </StackPanel>

無需在此XAML其他類唯一的解決辦法。當然，你必須適應你的需求（例如綁定）。我省略了不必要的屬性。

來源

2013-06-25 09:08:50 JeffRSon

如何設置綁定到文本框的標籤的可見性？

回答

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