using System; using System.Collections.Generic; using System.Globalization; using System.Text; using System.Windows; using System.Windows.Data; namespace ex_TextBox_PlaceHolder { class Bool2VisibilityConverter : IMultiValueConverter { public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture) { bool isEmpty = (bool)values[0]; bool hasFocus = (bool)values[1]; if(!isEmpty || hasFocus) { return Visibility.Collapsed; } return Visibility.Visible; } public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture) { throw new NotImplementedException(); } } }