.net - 如何反转 BooleanToVisibilityConverter？

Question

我BooleanToVisibilityConverter在 WPF 中使用 a 将Visibility控件的属性绑定到Boolean. 这很好用，但如果布尔值是，我希望其中一个控件隐藏，如果是true，则显示false。

score 271 · Accepted Answer

您可以通过使用通用IValueConverter实现来实现相同的目标，而不是反转，该实现可以将布尔值转换为可配置的真假目标值。下面是一种这样的实现：

public class BooleanConverter<T> : IValueConverter
{
    public BooleanConverter(T trueValue, T falseValue)
    {
        True = trueValue;
        False = falseValue;
    }

    public T True { get; set; }
    public T False { get; set; }

    public virtual object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return value is bool && ((bool) value) ? True : False;
    }

    public virtual object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return value is T && EqualityComparer<T>.Default.Equals((T) value, True);
    }
}

接下来，将其子类化 where Tis Visibility：

public sealed class BooleanToVisibilityConverter : BooleanConverter<Visibility>
{
    public BooleanToVisibilityConverter() : 
        base(Visibility.Visible, Visibility.Collapsed) {}
}

最后，这就是您可以BooleanToVisibilityConverter在 XAML 中使用上述方法并将其配置为例如使用Collapsedfor true 和Visiblefor false 的方式：

<Application.Resources>
    <app:BooleanToVisibilityConverter 
        x:Key="BooleanToVisibilityConverter" 
        True="Collapsed" 
        False="Visible" />
</Application.Resources>

IsHidden当您要绑定到名为as的布尔属性时，此反转很有用IsVisible。

score 49 · Accepted Answer

自己写是目前最好的解决方案。这是一个转换器的示例，它可以正常和反转两种方式。如果您对此有任何问题，请询问。

[ValueConversion(typeof(bool), typeof(Visibility))]
public class InvertableBooleanToVisibilityConverter : IValueConverter
{
    enum Parameters
    {
        Normal, Inverted
    }

    public object Convert(object value, Type targetType,
                          object parameter, CultureInfo culture)
    {
        var boolValue = (bool)value;
        var direction = (Parameters)Enum.Parse(typeof(Parameters), (string)parameter);

        if(direction == Parameters.Inverted)
            return !boolValue? Visibility.Visible : Visibility.Collapsed;

        return boolValue? Visibility.Visible : Visibility.Collapsed;
    }

    public object ConvertBack(object value, Type targetType,
        object parameter, CultureInfo culture)
    {
        return null;
    }
}

<UserControl.Resources>
  <Converters:InvertableBooleanToVisibilityConverter x:Key="_Converter"/>
</UserControl.Resources>

<Button Visibility="{Binding IsRunning, Converter={StaticResource _Converter}, ConverterParameter=Inverted}">Start</Button>

score 48 · Accepted Answer

using System;
using System.Globalization;
using System.Windows;
using System.Windows.Data;

public sealed class BooleanToVisibilityConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        var flag = false;
        if (value is bool)
        {
            flag = (bool)value;
        }
        else if (value is bool?)
        {
            var nullable = (bool?)value;
            flag = nullable.GetValueOrDefault();
        }
        if (parameter != null)
        {
            if (bool.Parse((string)parameter))
            {
                flag = !flag;
            }
        }
        if (flag)
        {
            return Visibility.Visible;
        }
        else
        {
            return Visibility.Collapsed;
        }
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        var back = ((value is Visibility) && (((Visibility)value) == Visibility.Visible));
        if (parameter != null)
        {
            if ((bool)parameter)
            {
                back = !back;
            }
        }
        return back;
    }
}

然后将 true 或 false 作为 ConverterParameter 传递

       <Grid.Visibility>
                <Binding Path="IsYesNoButtonSetVisible" Converter="{StaticResource booleanToVisibilityConverter}" ConverterParameter="true"/>
        </Grid.Visibility>

score 21 · Accepted Answer

实现您自己的 IValueConverter 实现。示例实现位于

http://msdn.microsoft.com/en-us/library/system.windows.data.ivalueconverter.aspx

在您的 Convert 方法中，让它返回您想要的值而不是默认值。

score 20 · Accepted Answer

Codeplex 上还有WPF 转换器项目。在他们的文档中，他们说您可以使用他们的MapConverter将 Visibility 枚举转换为 bool

<Label>
    <Label.Visible>
        <Binding Path="IsVisible">
            <Binding.Converter>
                <con:MapConverter>
                    <con:Mapping From="True" To="{x:Static Visibility.Visible}"/>
                    <con:Mapping From="False" To="{x:Static Visibility.Hidden}"/>
                </con:MapConverter>
            </Binding.Converter>
        </Binding>
    </Label.Visible>
</Label>

score 20 · Accepted Answer

将 ViewModel 布尔值 (IsButtonVisible) 与 xaml 控件可见性属性绑定的另一种方法。没有编码，没有转换，只是样式。

<Style TargetType={x:Type Button} x:Key="HideShow">
   <Style.Triggers>
      <DataTrigger Binding="{Binding IsButtonVisible}" Value="False">
          <Setter Property="Visibility" Value="Hidden"/>
      </DataTrigger>
   </Style.Triggers>
</Style>

<Button Style="{StaticResource HideShow}">Hello</Button>

score 18 · Accepted Answer

或者真正的懒人方式，只需利用已有的东西并翻转它：

public class InverseBooleanToVisibilityConverter : IValueConverter
{
    private BooleanToVisibilityConverter _converter = new BooleanToVisibilityConverter();

    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        var result = _converter.Convert(value, targetType, parameter, culture) as Visibility?;
        return result == Visibility.Collapsed ? Visibility.Visible : Visibility.Collapsed;
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        var result = _converter.ConvertBack(value, targetType, parameter, culture) as bool?;
        return result == true ? false : true;
    }
}

score 11 · Accepted Answer

如果您不喜欢编写自定义转换器，可以使用数据触发器来解决此问题：

<Style.Triggers>
        <DataTrigger Binding="{Binding YourBinaryOption}" Value="True">
                 <Setter Property="Visibility" Value="Visible" />
        </DataTrigger>
        <DataTrigger Binding="{Binding YourBinaryOption}" Value="False">
                 <Setter Property="Visibility" Value="Collapsed" />
        </DataTrigger>
</Style.Triggers>

score 3 · Accepted Answer

我刚刚在这方面做了一个帖子。我使用了与 Michael Hohlios 类似的想法。只是，我使用了属性而不是使用“对象参数”。

在我看来，使用属性将可见性绑定到 WPF 中的布尔值

使其更具可读性。

<local:BoolToVisibleOrHidden x:Key="BoolToVisConverter" Collapse="True" Reverse="True" />

score 3 · Accepted Answer

这是我写过并经常使用的一个。它使用一个布尔转换器参数来指示是否反转该值，然后使用 XOR 执行否定：

[ValueConversion(typeof(bool), typeof(System.Windows.Visibility))]
public class BooleanVisibilityConverter : IValueConverter
{
    System.Windows.Visibility _visibilityWhenFalse = System.Windows.Visibility.Collapsed;

    /// <summary>
    /// Gets or sets the <see cref="System.Windows.Visibility"/> value to use when the value is false. Defaults to collapsed.
    /// </summary>
    public System.Windows.Visibility VisibilityWhenFalse
    {
        get { return _visibilityWhenFalse; }
        set { _visibilityWhenFalse = value; }
    }

    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        bool negateValue;
        Boolean.TryParse(parameter as string, out negateValue);

        bool val = negateValue ^ System.Convert.ToBoolean(value); //Negate the value when negateValue is true using XOR
        return val ? System.Windows.Visibility.Visible : _visibilityWhenFalse;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        bool negateValue;
        Boolean.TryParse(parameter as string, out negateValue);

        if ((System.Windows.Visibility)value == System.Windows.Visibility.Visible)
            return true ^ negateValue;
        else
            return false ^ negateValue;
    }
}

这是一个 XOR 真值表供参考：

score 2 · Accepted Answer

我正在寻找更一般的答案，但找不到。我写了一个可以帮助别人的转换器。

它基于我们需要区分六种不同情况的事实：

真 2 可见，假 2 隐藏
真 2 可见，假 2 折叠
真 2 隐藏，假 2 可见
真 2 已折叠，假 2 可见
真 2 隐藏，假 2 折叠
真 2 折叠，假 2 隐藏

这是我对前 4 个案例的实现：

[ValueConversion(typeof(bool), typeof(Visibility))]
public class BooleanToVisibilityConverter : IValueConverter
{
    enum Types
    {
        /// <summary>
        /// True to Visible, False to Collapsed
        /// </summary>
        t2v_f2c,
        /// <summary>
        /// True to Visible, False to Hidden
        /// </summary>
        t2v_f2h,
        /// <summary>
        /// True to Collapsed, False to Visible
        /// </summary>
        t2c_f2v,
        /// <summary>
        /// True to Hidden, False to Visible
        /// </summary>
        t2h_f2v,
    }
    public object Convert(object value, Type targetType,
                          object parameter, CultureInfo culture)
    {
        var b = (bool)value;
        string p = (string)parameter;
        var type = (Types)Enum.Parse(typeof(Types), (string)parameter);
        switch (type)
        {
            case Types.t2v_f2c:
                return b ? Visibility.Visible : Visibility.Collapsed; 
            case Types.t2v_f2h:
                return b ? Visibility.Visible : Visibility.Hidden; 
            case Types.t2c_f2v:
                return b ? Visibility.Collapsed : Visibility.Visible; 
            case Types.t2h_f2v:
                return b ? Visibility.Hidden : Visibility.Visible; 
        }
        throw new NotImplementedException();
    }

    public object ConvertBack(object value, Type targetType,
        object parameter, CultureInfo culture)
    {
        var v = (Visibility)value;
        string p = (string)parameter;
        var type = (Types)Enum.Parse(typeof(Types), (string)parameter);
        switch (type)
        {
            case Types.t2v_f2c:
                if (v == Visibility.Visible)
                    return true;
                else if (v == Visibility.Collapsed)
                    return false;
                break;
            case Types.t2v_f2h:
                if (v == Visibility.Visible)
                    return true;
                else if (v == Visibility.Hidden)
                    return false;
                break;
            case Types.t2c_f2v:
                if (v == Visibility.Visible)
                    return false;
                else if (v == Visibility.Collapsed)
                    return true;
                break;
            case Types.t2h_f2v:
                if (v == Visibility.Visible)
                    return false;
                else if (v == Visibility.Hidden)
                    return true;
                break;
        }
        throw new InvalidOperationException();
    }
}

例子：

Visibility="{Binding HasItems, Converter={StaticResource BooleanToVisibilityConverter}, ConverterParameter='t2v_f2c'}"

我认为参数很容易记住。

希望它可以帮助某人。

score 2 · Accepted Answer

您可以使用QuickConverter。

使用 QuickConverter，您可以使用 BindingExpression 内联编写转换器逻辑

这是一个反转的 BooleanToVisibility 转换器：

Visibility="{qc:Binding '!$P ? Visibility.Visible : Visibility.Collapsed', P={Binding Example}}"

您可以通过 NuGet 添加 QuickConverter。查看设置文档。链接：https ://quickconverter.codeplex.com/

score 2 · Accepted Answer

与其编写自己的代码/重新发明，不如考虑使用CalcBinding：

    // Automatic two way convertion of bool expression to Visibility and 
    // back if target property has such type: description
    
    <Button Visibility="{c:Binding !IsChecked}" /> 
    <Button Visibility="{c:Binding IsChecked, FalseToVisibility=Hidden}" />

CalcBinding 对于许多其他场景也非常有用。

score 1 · Accepted Answer

写你自己的转换。

public class ReverseBooleanToVisibilityConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
   {
       // your converter code here
   }
}

score 0 · Accepted Answer

一个简单的单向版本，可以像这样使用：

Visibility="{Binding IsHidden, Converter={x:Static Ui:Converters.BooleanToVisibility}, ConverterParameter=true}

可以这样实现：

public class BooleanToVisibilityConverter : IValueConverter
{
  public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
  {
    var invert = false;

    if (parameter != null)
    {
      invert = Boolean.Parse(parameter.ToString());
    }

    var booleanValue = (bool) value;

    return ((booleanValue && !invert) || (!booleanValue && invert)) 
      ? Visibility.Visible : Visibility.Collapsed;
  }

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

score 0 · Accepted Answer

将所有内容转换为所有内容（布尔、字符串、枚举等）：

public class EverythingConverterValue
{
    public object ConditionValue { get; set; }
    public object ResultValue { get; set; }
}

public class EverythingConverterList : List<EverythingConverterValue>
{

}

public class EverythingConverter : IValueConverter
{
    public EverythingConverterList Conditions { get; set; } = new EverythingConverterList();

    public object NullResultValue { get; set; }
    public object NullBackValue { get; set; }

    public object Convert(object value, Type targetType,
        object parameter, CultureInfo culture)
    {
        return Conditions.Where(x => x.ConditionValue.Equals(value)).Select(x => x.ResultValue).FirstOrDefault() ?? NullResultValue;
    }
    public object ConvertBack(object value, Type targetType,
        object parameter, CultureInfo culture)
    {
        return Conditions.Where(x => x.ResultValue.Equals(value)).Select(x => x.ConditionValue).FirstOrDefault() ?? NullBackValue;
    }
}

XAML 示例：

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                xmlns:conv="clr-namespace:MvvmGo.Converters;assembly=MvvmGo.WindowsWPF"
                xmlns:sys="clr-namespace:System;assembly=mscorlib">

<conv:EverythingConverter x:Key="BooleanToVisibilityConverter">
    <conv:EverythingConverter.Conditions>
        <conv:EverythingConverterValue ResultValue="{x:Static Visibility.Visible}">
            <conv:EverythingConverterValue.ConditionValue>
                <sys:Boolean>True</sys:Boolean>
            </conv:EverythingConverterValue.ConditionValue>
        </conv:EverythingConverterValue>
        <conv:EverythingConverterValue ResultValue="{x:Static Visibility.Collapsed}">
            <conv:EverythingConverterValue.ConditionValue>
                <sys:Boolean>False</sys:Boolean>
            </conv:EverythingConverterValue.ConditionValue>
        </conv:EverythingConverterValue>
    </conv:EverythingConverter.Conditions>

</conv:EverythingConverter>

<conv:EverythingConverter x:Key="InvertBooleanToVisibilityConverter">
    <conv:EverythingConverter.Conditions>
        <conv:EverythingConverterValue ResultValue="{x:Static Visibility.Visible}">
            <conv:EverythingConverterValue.ConditionValue>
                <sys:Boolean>False</sys:Boolean>
            </conv:EverythingConverterValue.ConditionValue>
        </conv:EverythingConverterValue>
        <conv:EverythingConverterValue ResultValue="{x:Static Visibility.Collapsed}">
            <conv:EverythingConverterValue.ConditionValue>
                <sys:Boolean>True</sys:Boolean>
            </conv:EverythingConverterValue.ConditionValue>
        </conv:EverythingConverterValue>
    </conv:EverythingConverter.Conditions>
</conv:EverythingConverter>

<conv:EverythingConverter x:Key="MarriedConverter" NullResultValue="Single">
    <conv:EverythingConverter.Conditions>
        <conv:EverythingConverterValue ResultValue="Married">
            <conv:EverythingConverterValue.ConditionValue>
                <sys:Boolean>True</sys:Boolean>
            </conv:EverythingConverterValue.ConditionValue>
        </conv:EverythingConverterValue>
        <conv:EverythingConverterValue ResultValue="Single">
            <conv:EverythingConverterValue.ConditionValue>
                <sys:Boolean>False</sys:Boolean>
            </conv:EverythingConverterValue.ConditionValue>
        </conv:EverythingConverterValue>
    </conv:EverythingConverter.Conditions>
    <conv:EverythingConverter.NullBackValue>
        <sys:Boolean>False</sys:Boolean>
    </conv:EverythingConverter.NullBackValue>
</conv:EverythingConverter>

score -2 · Accepted Answer

我知道这已经过时了，但是，你不需要重新实现任何东西。

我所做的是否定属性的值，如下所示：

<!-- XAML code -->
<StackPanel Name="x"  Visibility="{Binding    Path=Specials, ElementName=MyWindow, Converter={StaticResource BooleanToVisibilityConverter}}"></StackPanel>    
<StackPanel Name="y"  Visibility="{Binding Path=NotSpecials, ElementName=MyWindow, Converter={StaticResource BooleanToVisibilityConverter}}"></StackPanel>

……

//Code behind
public bool Specials
{
    get { return (bool) GetValue(SpecialsProperty); }
    set
    {
        NotSpecials= !value; 
        SetValue(SpecialsProperty, value);
    }
}

public bool NotSpecials
{
    get { return (bool) GetValue(NotSpecialsProperty); }
    set { SetValue(NotSpecialsProperty, value); }
}

它工作得很好！

我错过了什么吗？

.net - 如何反转 BooleanToVisibilityConverter？

17 回答 17

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