wpf Value and Multivalue Converters Using MarkupExtension with Converters to skip recource declaration
Example
Usually to use the converter, we have to define it as resource in the following way:
<converters:SomeConverter x:Key="SomeConverter"/>
It is possible to skip this step by defining a converter as MarkupExtension and implementing the method ProvideValue. The following example converts a value to its negative:
namespace MyProject.Converters
{
public class Converter_Negative : MarkupExtension, IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
return this.ReturnNegative(value);
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
return this.ReturnNegative(value);
}
private object ReturnNegative(object value)
{
object result = null;
var @switch = new Dictionary<Type, Action> {
{ typeof(bool), () => result=!(bool)value },
{ typeof(byte), () => result=-1*(byte)value },
{ typeof(short), () => result=-1*(short)value },
{ typeof(int), () => result=-1*(int)value },
{ typeof(long), () => result=-1*(long)value },
{ typeof(float), () => result=-1f*(float)value },
{ typeof(double), () => result=-1d*(double)value },
{ typeof(decimal), () => result=-1m*(decimal)value }
};
@switch[value.GetType()]();
if (result == null) throw new NotImplementedException();
return result;
}
public Converter_Negative()
: base()
{
}
private static Converter_Negative _converter = null;
public override object ProvideValue(IServiceProvider serviceProvider)
{
if (_converter == null) _converter = new Converter_Negative();
return _converter;
}
}
}
Using the converter:
-
Define namespace
xmlns:converters="clr-namespace:MyProject.Converters;assembly=MyProject"
-
Example use of this converter in binding
<RichTextBox IsReadOnly="{Binding Path=IsChecked, ElementName=toggleIsEnabled, Converter={converters:Converter_Negative}}"/>
