pass multiple binded values as binding CONVERTER PARAMETER

Question

I need to pass two values (in may case named Unit and Quantity) as the converter parameter to a binding converter.(Note that I do not need to pass these values as binding values (multibinding), I need to pass them as binding converter parameter because, I need both Convert and ConvertBack methods of converter). The only way that I was thought that works was to create a new class UnitQuantityBindClass to set them in that class and pass this class as converter parameter but this class does not get bind values and when I go through the converter, the converter parameter , which is the created class, does not have values. can an one help me on this?

public class UnitQuantityBindClass:DependencyObject
{
    public static readonly DependencyProperty QuantityProperty = DependencyProperty.Register(
        "Quantity", typeof(EQuantities), typeof(UnitQuantityBindClass));

    public EQuantities Quantity
    {
        get { return (EQuantities)GetValue(QuantityProperty); }
        set { SetValue(QuantityProperty, value); }
    }

    public static readonly DependencyProperty UnitProperty = DependencyProperty.Register(
        "Unit", typeof(Enum), typeof(UnitQuantityBindClass));

    public Enum Unit
    {
        get { return (Enum)GetValue(UnitProperty); }
        set { SetValue(UnitProperty, value); }
    }
}

Usage:

<textboxunitconvertor:TextBoxUnitConvertor Name="gasDensityValueControl" InstantaneousConvert="True" Margin="96,163,0,0" IsEnabled="{Binding ElementName=chkGas,Path=IsChecked}" QuantityBind="{Binding _FluidBlackOilClass.SGGas_SC.Quantity , RelativeSource={RelativeSource AncestorType=Window}, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}"  Width="206" Height="28" HorizontalAlignment="Left" VerticalAlignment="Top">
    <textboxunitconvertor:TextBoxUnitConvertor.TextBoxText>
        <Binding Path="_FluidBlackOilClass.SGGas_SC.Value" RelativeSource="{RelativeSource AncestorType=Window}" UpdateSourceTrigger="PropertyChanged" Mode="TwoWay" Converter="{StaticResource ValueStorageForUnitConverter}">
             <Binding.ConverterParameter>
                 <classes:UnitQuantityBindClass
                     Quantity="{Binding ElementName=gasDensityValueControl,
                                Converter={StaticResource DummyConverter},
                                Path=_Quantity,
                                UpdateSourceTrigger=PropertyChanged,
                                Mode=TwoWay,
                                PresentationTraceSources.TraceLevel=High}"
                     Unit="{Binding ElementName=gasDensityValueControl,
                            Path=_CurrentUnitEnum,
                            UpdateSourceTrigger=PropertyChanged,
                            Mode=TwoWay}" />
             </Binding.ConverterParameter>
        </Binding>
    </textboxunitconvertor:TextBoxUnitConvertor.TextBoxText>
</textboxunitconvertor:TextBoxUnitConvertor>   

Note: my requirement is to get "_FluidBlackOilClass.SGGas_SC.Value" and pass it to the converter and also i need to pass "_Quantity" and "_CurrentUnitEnum" as the converters parameter to convert the "_FluidBlackOilClass.SGGas_SC.Value" according to the "_Quantity" and "_CurrentUnitEnum" to a new value and set it as TextBoxText. also i need to convertback the TextBoxText to store in the "_FluidBlackOilClass.SGGas_SC.Value" according to the "_Quantity" and "_CurrentUnitEnum".

Answer 1

1. Make your Converter inherit Freezable, and introduce a DP called SourceTextBox which will get the reference to your TextBox, then in your Convert and ConvertBack methods, you can use this reference to get the needed properties.

   public class BindableConverter : Freezable, IValueConverter
   {
       #region Overrides of Freezable    
       protected override Freezable CreateInstanceCore()
       {
           return new BindableConverter();
       }    
       #endregion       
   
       public TextBox SourceTextBox
       {
           get { return (TextBox)GetValue(SourceTextBoxProperty); }
           set { SetValue(SourceTextBoxProperty, value); }
       }
   
       // Using a DependencyProperty as the backing store for SourceTextBox.  This enables animation, styling, binding, etc...
       public static readonly DependencyProperty SourceTextBoxProperty =
           DependencyProperty.Register("SourceTextBox", typeof(TextBox), typeof(BindableConverter), new PropertyMetadata(null));
   
   
       public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
       {
           // ... do something with SourceTextBox here
       }
   
       public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
       {
           // ... do something
       }
   }
   

2. Usage :

   <textboxunitconvertor:TextBoxUnitConvertor Name="gasDensityValueControl" ... >
      <textboxunitconvertor:TextBoxUnitConvertor.Resources>
         <local:BindableConverter x:Key="ValueStorageForUnitConverter" SourceTextBox="{Binding ElementName=gasDensityValueControl}"/>
      </textboxunitconvertor:TextBoxUnitConvertor.Resources>
      ...
   </textboxunitconvertor:TextBoxUnitConvertor>