为什么我的 TypeConverter 没有被调用？

Question

我已将 TypeConverterAttribute 属性应用于我的 WPF FrameworkElement 子类的属性。该属性的类型为 BitmapSource。

但从未创建或调用 TypeConverter。是不是因为 ImageSource 上指定的 TypeConverter 优先？

我正在尝试调试数据绑定问题。错误信息，从未提及我的 TypeConverter 类，提示将属性添加到属性没有效果：

System.Windows.Data Error: 6 : 'TargetDefaultValueConverter' converter failed to convert value '../SmallItemIcons/Gallery.png' (type 'String'); fallback value will be used, if available. BindingExpression:Path=SmallImage.ImageUri; DataItem='ItemSettings' (HashCode=32104365); target element is 'Bitmap' (Name=''); target property is 'Source' (type 'BitmapSource') IOException:'System.IO.IOException: Cannot locate resource 'smallitemicons/gallery.png'.
   at MS.Internal.AppModel.ResourcePart.GetStreamCore(FileMode mode, FileAccess access)
   at System.IO.Packaging.PackagePart.GetStream(FileMode mode, FileAccess access)
   at System.IO.Packaging.PackWebResponse.CachedResponse.GetResponseStream()
   at System.IO.Packaging.PackWebResponse.GetResponseStream()
   at System.IO.Packaging.PackWebResponse.get_ContentType()
   at System.Windows.Media.Imaging.BitmapDecoder.SetupDecoderFromUriOrStream(Uri uri, Stream stream, BitmapCacheOption cacheOption, Guid& clsId, Boolean& isOriginalWritable, Stream& uriStream, UnmanagedMemoryStream& unmanagedMemoryStream, SafeFileHandle& safeFilehandle)
   at System.Windows.Media.Imaging.BitmapDecoder.CreateFromUriOrStream(Uri baseUri, Uri uri, Stream stream, BitmapCreateOptions createOptions, BitmapCacheOption cacheOption, RequestCachePolicy uriCachePolicy, Boolean insertInDecoderCache)
   at System.Windows.Media.Imaging.BitmapFrame.CreateFromUriOrStream(Uri baseUri, Uri uri, Stream stream, BitmapCreateOptions createOptions, BitmapCacheOption cacheOption, RequestCachePolicy uriCachePolicy)
   at System.Windows.Media.ImageSourceConverter.ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, Object value)
   at MS.Internal.Data.DefaultValueConverter.ConvertHelper(Object o, Type destinationType, DependencyObject targetElement, CultureInfo culture, Boolean isForward)
   at MS.Internal.Data.TargetDefaultValueConverter.Convert(Object o, Type type, Object parameter, CultureInfo culture)
   at System.Windows.Data.BindingExpression.ConvertHelper(IValueConverter converter, Object value, Type targetType, Object parameter, CultureInfo culture)'

Answer 1

我之前遇到过这个问题并忽略了它，因为我拥有拥有正在转换的课程的奢侈。但是，我刚刚尝试过，可以确认according to MSDN 它应该 工作。也就是说，它似乎确实不起作用。

我在 WPF Disciples forum 上提出了这个问题，我还提供了一个解决方法。

Answer 2

您必须在 xaml 中创建转换对象才能在绑定中使用它。查看this article

<local:MyConverter key="myconverterorsomething"/>

<TextBlock Text="{Binding Path=TimeOfSale, 
  Converter={StaticResource myconverterorsomething}, 
  ConverterParameter=' \{0:dd-MMM-yyyy hh:mm\}'}" />