Can I change the properties of a binding in a DataTrigger, without knowing the binding itself?

Question

I have a TextBox style that formats a number if the box is unfocused, but leaves the number unformatted whlie it\'s being edited.

This is the style I wa

Answer 1

Is there a way I can make this style generic, such as only changing the StringFormat property of the binding in the DataTrigger?

Inherit Style and new XAML would become this:

Here's the class...

public class FlyingStyle : Style
{
    public FlyingStyle()
        : base(typeof(TextBox))
    { }

    string _stringFormat;
    public string StringFormat
    {
        get { return _stringFormat; }
        set
        {
            _stringFormat = value;
            CheckInitialize();
        }
    }
    Binding _binding;
    public Binding Binding
    {
        get { return _binding; }
        set
        {
            _binding = value;
            CheckInitialize();
        }
    }
    void CheckInitialize()
    {
        if (StringFormat == null || Binding == null) { return; }// need both

        Setters.Add(CreateSetter(Binding, StringFormat));

        var trigger = new Trigger
        {
            Property = UIElement.IsKeyboardFocusWithinProperty,
            Value = true,
        };
        trigger.Setters.Add(CreateSetter(Binding));
        Triggers.Add(trigger);
    }

    /// 
Creates the common .
    static Setter CreateSetter(Binding binding, string stringFormat = null)
    {
        // must create a copy, because same binding ref but diff StringFormats
        var bindingCopy = new Binding
        {
            // these could be copies as well
            UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged,
            ValidatesOnDataErrors = true,
            Mode = BindingMode.TwoWay,
            Path = binding.Path,

            AsyncState = binding.AsyncState,
            BindingGroupName = binding.BindingGroupName,
            BindsDirectlyToSource = binding.BindsDirectlyToSource,
            Converter = binding.Converter,
            ConverterCulture = binding.ConverterCulture,
            ConverterParameter = binding.ConverterParameter,
            ElementName = binding.ElementName,
            FallbackValue = binding.FallbackValue,
            IsAsync = binding.IsAsync,
            NotifyOnSourceUpdated = binding.NotifyOnSourceUpdated,
            NotifyOnTargetUpdated = binding.NotifyOnTargetUpdated,
            NotifyOnValidationError = binding.NotifyOnValidationError,
            //StringFormat = set below...
            TargetNullValue = binding.TargetNullValue,
            UpdateSourceExceptionFilter = binding.UpdateSourceExceptionFilter,
            ValidatesOnExceptions = binding.ValidatesOnExceptions,
            XPath = binding.XPath,
            //ValidationRules = binding.ValidationRules
        };
        // mutex ElementName, so modify if needed
        // Source = binding.Source,
        // RelativeSource = binding.RelativeSource,

        if (stringFormat != null)
        {
            bindingCopy.StringFormat = stringFormat;
        }
        return new Setter(TextBox.TextProperty, bindingCopy);
    }
}

Note that my test was

• the generic MainWindow
• impl INotifyPropertyChanged
• SomeValue INPC property
• DataContext = this
• x:Name = This