Question

在Silverlight中，我有一个标准的IValueConverter，我想将可能的参数定义为const字符串。

public class BooleanConverter : IValueConverter
{
    public const string PARAMETER_ONE = "one";
    public const string PARAMETER_TWO  = "two";
...

然后我想在转换器参数中使用常量，例如：

    <TextBlock Text="{Binding Name, Converter={StaticResource BooleanConverter},
        ConverterParameter={StaticResource BooleanConvereter.PARAMETER_TWO}" />

这可能吗？如果是，那么正确的语法是什么？

Answer 1

您应该能够使用静态标记扩展名：

<TextBlock Text="{Binding Name,Converter={StaticResource BooleanConverter},ConverterParameter={x:Static cnv:BooleanConverter.PARAMETER_ONE}}" />

请注意，x:Static需要引用类本身，而不是您的资源。因此，您需要在其前面添加适当的XML名称空间前缀。

Answer 2

您可以同时使用参数和参数。样品：

<converters:VisibilityConverter x:Key="inversVisibConverter" Inverse="True"/>

 Visibility="{Binding ABoolValue, Mode=OneWay, Converter={StaticResource inversVisibConverter},ConverterParameter=abc}"

转换器（包含参数和参数）：

public sealed class VisibilityConverter : IValueConverter {

       public bool Inverse { get; set; }

       #region Implementation of IValueConverter
        object IValueConverter.Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {            
            Visibility visibility = Visibility.Visible;

            if (value is bool)
            {
                visibility = (bool) value ? Visibility.Visible : Visibility.Collapsed;
            }

            if( parameter != null )
            {
                //handle parameter here:

            }

            if (Inverse)
            {
                visibility = (visibility == Visibility.Visible) ? Visibility.Collapsed : Visibility.Visible;
            }

            return visibility;
        }

        object IValueConverter.ConvertBack(object value, Type targetType, object parameter, CultureInfo culture) {
            if (!(value is Visibility)) {
                throw new ArgumentOutOfRangeException("value", "VisibilityConverter can only convert from Visibility");
            }

            if (targetType == typeof(bool)) {
                return ((Visibility)value == Visibility.Visible) ? true : false;
            }

            throw new ArgumentOutOfRangeException("targetType", "VisibilityConverter can only convert to Boolean");
        }
        #endregion
 }

是否可以在转换器参数中使用IValueConverter的静态值？

2 个答案: