How to boolean && two visibility converters

I have two separate converters for visibility, one based on whether a field has been updated and one based on whether a field is allowed to be seen. I use the updatedField one for each text item on my page so that a star shows up next to an updated field. But some text items only are visible to some users based on permission levels.

For example:

<Image Visibility="{Binding ElementName=MyObject, Path=UpdatedFields, Mode=OneWay, Converter={StaticResource updatedFieldConverter}, ConverterParameter=FieldToTest}" Source="Properties:Resources.star_yellow" />

and

<TextBlock FontSize="21" Foreground="{DynamicResource LabelBrush}" Text="{x:Static Properties:Resources.Some_Text}" Visibility="{Binding Source={StaticResource allowedFields}, Path=Some_Text_Field, Converter={StaticResource visibilityConverter}}" />

My problem is that for the case of the permission-required fields I need to run both converters to determine if the star shows up. Is there a way to do a boolean "And" on the results of two converters?

I looked at this post but it doesn't seem to allow for different sets of parameters to be passed into to the two different converters.

-------Update--------

I also tried to create a MultiValueConverter with this xaml

<Image Grid.Row="4" Grid.Column="0" Source="star_yellow.png">
   <Image.Visibility>
      <MultiBinding Converter="{StaticResource combinedVisibilityConverter}" ConverterParameter="FieldToTest" >
         <Binding ElementName="allowedFieldsModel" Path="Some_Text_Field" Mode="OneWay" />                        
         <Binding ElementName="MyObject" Path="UpdatedFields" Mode="OneWay" />
      </MultiBinding>
   </Image.Visibility>
</Image>

But when it enters the converter both values are "DependencyProperty.UnsetValue". So I'm apparently doing something wrong here.

--------Solution---------

I had to modify to this, but then it worked.

<Image.Visibility>
    <MultiBinding Converter="{StaticResource combinedVisibilityConverter}" ConverterParameter="FieldToTest">
        <Binding Source="{StaticResource allowedFieldsModel}" Path="Some_Text_Field" />
        <Binding Path="MyObject.UpdatedFields" />
    </MultiBinding>
</Image.Visibility>

You could use a MultiBinding together with a short, hand made IMultiValueConverter.

Example:

<StackPanel>
    <StackPanel.Resources>
        <local:MultiBooleanToVisibilityConverter x:Key="Converter" />
    </StackPanel.Resources>
    <CheckBox x:Name="Box1" />
    <CheckBox x:Name="Box2" />
    <TextBlock Text="Hidden Text">
        <TextBlock.Visibility>
            <MultiBinding Converter="{StaticResource Converter}">
                <Binding ElementName="Box1"
                            Path="IsChecked" />
                <Binding ElementName="Box2"
                            Path="IsChecked" />
            </MultiBinding>
        </TextBlock.Visibility>
    </TextBlock>                   
</StackPanel>

... and the converter ...

class MultiBooleanToVisibilityConverter : IMultiValueConverter
{
    public object Convert(object[] values,
                            Type targetType,
                            object parameter,
                            System.Globalization.CultureInfo culture)
    {
        bool visible = true;
        foreach (object value in values)
            if (value is bool)
                visible = visible && (bool)value;

        if (visible)
            return System.Windows.Visibility.Visible;
        else
            return System.Windows.Visibility.Hidden;
    }

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

Asheh

Late to the party here but an easier solution is to just wrap the control in another control. I prefer this to having lots of Converters that do different things.

<Border Visibility="{Binding Value1, Converter={convertersDF:Converter_ValueToVisibility}}">
 <ComboBox Visibility="{Binding Value2, Converter={convertersDF:Converter_ValueToVisibility}}"/>
</Border>

One thing that came to mind is, perhaps, instead of two different boolean fields, a single bit field created by ORing together updatedField and allowedField. Then you can have three value converters, all operating on the same field.

Or just calculate another field in your data model that does the ANDing there. That's probably more efficient (in terms of runtime).

You could pass an array of two objects to the converter in the ConverterParameter - constructing the array in XAML.

来源：https://stackoverflow.com/questions/6501970/how-to-boolean-two-visibility-converters

标签

wpf

data-binding

converter