WPF BooleanToVisibilityConverter,当为false时转换为隐藏而不是折叠?

不幸的是,它只能转换为可见或折叠,所以您必须自己编写。以下是根据反射器的转换方法:

public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
    bool flag = false;
    if (value is bool)
    {
        flag = (bool)value;
    }
    else if (value is bool?)
    {
        bool? nullable = (bool?)value;
        flag = nullable.HasValue ? nullable.Value : false;
    }
    return (flag ? Visibility.Visible : Visibility.Collapsed);
}

[ValueConversion(typeof(bool), typeof(Visibility))]
public sealed class BoolToVisibilityConverter : IValueConverter
{
  public Visibility TrueValue { get; set; }
  public Visibility FalseValue { get; set; }

  public BoolToVisibilityConverter()
  {
    // set defaults
    TrueValue = Visibility.Visible;
    FalseValue = Visibility.Collapsed;
  }

  public object Convert(object value, Type targetType, 
      object parameter, CultureInfo culture)
  {
    if (!(value is bool))
      return null;
    return (bool)value ? TrueValue : FalseValue;    
  }

  public object ConvertBack(object value, Type targetType, 
      object parameter, CultureInfo culture)
  {
    if (Equals(value, TrueValue))
      return true;
    if (Equals(value, FalseValue))
      return false;
    return null;
  }
}

使用它时,只需配置一个在XAML中完全满足您需要的版本,如下所示:

<Blah.Resources>
  <local:BoolToVisibilityConverter
         x:Key="BoolToHiddenConverter"
         TrueValue="Visible" FalseValue="Hidden" />
</Blah.Resources>

然后在一个或多个绑定中使用它,如下所示:

<Foo Visibility="{Binding IsItFridayAlready, 
                          Converter={StaticResource BoolToHiddenConverter}}" />

SILVERLIGHT用户 我必须放下枪 [ValueConversion] 作为该属性的声明不是Silverlight框架的一部分。它在WPF中也不是严格需要的,但与内置转换器是一致的。

style 而不是转换器?代码类似于:

<Style x:Key="Triggers" TargetType="Button">
    <Style.Triggers>
    <Trigger Property="{Binding ...}" Value="false">
        <Setter Property = "Visibility" Value="Hidden"/>
    </Trigger>
    </Style.Triggers>
</Style>

您需要自己提供绑定属性来指向bool属性。

要反转逻辑,只需在xaml代码中输入:ConverterParameter=reverse

public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
    bool flag = false;
    if (value is bool)
    {
        flag = (bool)value;
    }

    var reverse = parameter as string;
    if(reverse != null && reverse == "Reverse")
        flag != flag;

    return (flag ? Visibility.Visible : Visibility.Collapsed);
}

public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
    var boolValue = (bool) value;
    return boolValue ? Visibility.Visible : (parameter ?? Visibility.Hidden);
}

所以你可以这样绑定:

Visibility="{Binding SomeBool, Converter={StaticResource ResourceKey=BooleanToVisibilityConverter}, ConverterParameter={x:Static Visibility.Collapsed}}"

我有这个问题突然出现,我的解决方案可能是非常情境,但我会分享它无论如何。 由于我的环境,我能够模仿转换器,没有转换器,用一个简单的代码位。只有当绑定到textbox生成的数字框的变量(通过Regex确保其a数字)不是0时,我才改变可见性。整个代码都在下面,但是如果要在代码的其他地方更改布尔值,那么WPF和C的第一位才是真正需要的。 工作包:

    Visibility="{Binding Path=Visible}"

C级#

    public class foo : INotifyPropertyChanged
    {
        private bool vis = false;
        public object Visible
        {
            get 
            { 
                if (vis == true) 
                { 
                    return Visibility.Visible; 
                } 
                else 
                { 
                    return Visibility.Hidden; 
                } 
            }
            set
            { 
                vis = (bool)value; 
                OnPropertyChanged(nameof(Visible)); 
            }
        }
        public int Value_b
        {
            get 
            { 
                return base_value;
            }
            set
            { 
                base_value = value; 
                OnPropertyChanged(nameof(Value_b));
                if (base_value == 0) 
                { 
                    Visible = false; 
                } 
                else 
                { 
                    Visible = true; 
                } 
            }
        }

        public event PropertyChangedEventHandler PropertyChanged;
        protected virtual void OnPropertyChanged(string propertyName)
        {
            PropertyChanged?.Invoke(this, new 
            PropertyChangedEventArgs(propertyName));
        }
    }

在我看来,我有一个按钮,我想被隐藏,除非我的变量之一有一个正长度字符串:

<Button x:Name="SelectBinaryFilePath" Content="Select" Visibility="{Binding CanSelectBinaryFile}" />

public Visibility CanSelectBinaryFile
{
    get
    {
        return String.IsNullOrEmpty(FileSystemPath) ? Visibility.Hidden : Visibility.Visible;
    }
}

NotifyOfPropertyChange 以确保 CanSelectBinaryFile