Question

Is it possible to bind an ActualWidth or Width property of a Control to the Visibility of another Control with a distinction about value (like <200)? In my Opinion it is only possible with a converter because a DataTrigger can not work with > or <.

因此,我与一位老虎一起审判,但却没有工作。我不敢确定需要哪些类型的转换器,以及哪一种转换器需要这种解决办法。

x

<StackPanel>
    <Slider x:Name="slider" Height="36" Width="220" Maximum="500"/>
    <Rectangle x:Name="mover"  Height="12" Stroke="Black" Width="{Binding Value, ElementName=slider}"/>
    <Rectangle x:Name="rectangle" Fill="#FFFF9E0E" Height="34" Width="112" Visibility="{Binding ActualWidth, Converter={StaticResource umkehr}, ElementName=rectangle, Mode=OneWay}"/>
</StackPanel>

以及兑换人的想法:

public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
   if (value != null) {
       var val = System.Convert.ToDouble(value);
        if (val > 100)
            return Visibility.Visible;
        return Visibility.Collapsed;
    }
        return Visibility.Collapsed;
}

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

Answer 1

It is likely not w或king because you are binding your Rectangle s Visibility to the same rectangle s ActualWidth, and an invisible rectangle will always have a width of 0, so will never be visible.

Here s some examples. One binds to the other rectangle s ActualWidth, and the other binds to your Slider s Value

<Rectangle x:Name="rectangle" 
           Visibility="{Binding ActualWidth, ElementName=mover, 
               Converter={StaticResource umkehr}}"/>

或

<Rectangle x:Name="rectangle" 
           Visibility="{Binding Value, ElementName=slider, 
               Converter={StaticResource umkehr}}"/>

And as far as I know, there s no easy way of basing a value off of if something is greater than 或 less than a value. Coverters are your best option.

Answer 2

<代码>ActualWidth 是按框架类别分列的仅有的财产——

public double ActualWidth { get; }

It is get only property hence you can t set it to other value from code. You can bind to Width of your control instead to make it work.

http://www.ohchr.org。

对我来说,这可能是你想要的——

<><>载荷>

public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
    if (value is double)
    {
       return ((double)value > 100) ? Visibility.Visible : Visibility.Collapsed;
    }
    return Visibility.Collapsed;
}

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

XAML

<StackPanel>
   <Slider x:Name="slider" Height="36" Width="220" Maximum="500"/>
   <Rectangle x:Name="mover"  Height="12" Stroke="Black" Width="{Binding Value, ElementName=slider}"/>
    <Rectangle x:Name="rectangle" Fill="#FFFF9E0E" Height="34" Width="112" Visibility="{Binding ActualWidth, Converter={StaticResource MyConverter}, ElementName=mover, Mode=OneWay}"/>
</StackPanel>

Answer 3

http://msdn.microsoft.com/en-us/library/system.windows.uielement.visibility(v=vs.95).aspx”rel=“nofollow”Visibility, 依据MarkupExtension (inherit from Brel或Belles/code><>><>>>>>>>>>><<<<>>>>>>>>。



变相办法:

[ValueConversion(typeof(Double), typeof(Visibility))]
[ValueConversion(typeof(Double?), typeof(Visibility))]
public class MinimumLengthToVisibilityConverter : IValueConverter
{
    public Double MinLength { get; set; }

    public override Object Convert(Object value, Type targetType, Object parameter, CultureInfo culture)
    {
        if ((value == null) || !(value is Double))
        {
            return DependencyProperty.UnsetValue;
        }

        return (((Double)value) > MinLength) ? Visibility.Visible : Visibility.Collapsed;
    }

    public override Object ConvertBack(Object value, Type targetType, Object parameter, CultureInfo culture)
    {
        return DependencyProperty.UnsetValue;
    }
}


标记扩展选择:

http://blogs.msdn.com/b/mikehillberg/archive/ 2008/09/30/comparabledatatrigger.aspx” rel=“nofollow”

Answer 4

如果你需要:

public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            double cutoff = 0.0;

            if(parameter is double)
            {
                cutoff = (double)parameter;
            }

            if (parameter is string)
            {
                Double.TryParse(parameter.ToString(), out cutoff); 
            }

            if (value is double)
            {
                return ((double)value > cutoff) ? Visibility.Visible : Visibility.Collapsed;
            }
            return Visibility.Collapsed;
        }

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

并且:

<StackPanel>
    <Slider x:Name="slider" Height="36" Width="220" Maximum="500"/>
    <Rectangle x:Name="mover"  Height="12" Stroke="Black" Width="{Binding Value, ElementName=slider}"/>
     <Rectangle x:Name="rectangle" Fill="#FFFF9E0E" Height="34" Width="112" 
                Visibility="{Binding ActualWidth, Converter={StaticResource ActualWidthToVisibilityConverter},                                                                                               
                ElementName=mover, Mode=OneWay, ConverterParameter=100}"/>
</StackPanel>

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