如何在Visibility属性上执行简单的XAML（WPF）条件绑定

Question

I have got a view model with a property:

public class MyModel
{
    public bool IsEnabled {get;set;}
}

I want to use this property to toggle a button state. If the boolean is true I want to hide the button, and otherwise show it.

I tried things like:

<Button Visibility= "{Binding IsEnabled ? Hidden : Visible  }">Enable</Button>

But this doesn't fit.

I tried some more complex solution but my guess is, I am missing something trivial.

Any suggestions?

Answer 1

Since you want to toggle between Hidden and Visible and true is hidden you can either write custom IValueConverter or use simple Style.Trigger

<Button Content="Enable">
    <Button.Style>
        <Style TargetType="{x:Type Button}">
            <Setter Property="Visibility" Value="Visible"/>
            <Style.Triggers>
                <DataTrigger Binding="{Binding IsEnabled}" Value="True">
                    <Setter Property="Visibility" Value="Hidden"/>
                </DataTrigger>
            </Style.Triggers>                    
        </Style>
    </Button.Style>
</Button>

This is all assuming the DataContext is set accordingly and MyModel.IsEnabled raises INotifyPropertyChanged.PropertyChanged event whenever changed

public class MyModel : INotifyPropertyChanged
{
    private bool _isEnabled;

    public bool IsEnabled
    {
        get { return _isEnabled; }
        set
        {
            _isEnabled = value;
            OnPropertyChanged("IsEnabled");
        }
    }

    #region INotifyPropertyChanged

    public event PropertyChangedEventHandler PropertyChanged;

    protected void OnPropertyChanged(string propertyName)
    {
        var handler = PropertyChanged;
        if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
    }

    #endregion
}

Answer 2

Use the BooleanToVisibilityConverter:

<Window.Resources>
    <BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter" />
</Window.Resources>

<Button Visibility= "{Binding IsEnabled, Converter={StaticResource BooleanToVisibilityConverter}}" />

Answer 3

Add a class inheriting IValueConverter

public class BooleanToVisibilityConverter : IValueConverter
{

    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        bool bValue = (bool)value;
        if (bValue)
            return Visibility.Visible;
        else
            return Visibility.Collapsed;
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        Visibility visibility = (Visibility)value;

        if (visibility == Visibility.Visible)
            return true;
        else
            return false;
    }
    #endregion
}