Question

我有XAML解析异常“必须设置BitmapImage UriSource”。在解析时，我的转换器已创建，但未调用Convert（）方法。我做错了什么？

XAML：

<ImageBrush >
    <ImageBrush.ImageSource>
          <BitmapImage UriSource="{Binding Path=Value.Image, Converter={StaticResource imageConverter}, ConverterParameter=Value.Image}" CacheOption="OnLoad"></BitmapImage>
    </ImageBrush.ImageSource>
</ImageBrush>

C＃：

public class ImageConverter : IValueConverter
{
    public ImageConverter()
    {
    }
    public object Convert(object value, Type targetType,
                      object parameter, CultureInfo culture)
    {
        try
        {
            return new BitmapImage(new Uri((string)value));
        }
        catch
        {
            return new BitmapImage();
        }
    }

    public object ConvertBack(object value, Type targetType,
                              object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

Answer 1

我找到了一种解决方案。由于我只需要使用<BitmapImage>来设置CacheOption.OnLoad，因此我的本地源文件不会被锁定，我已经创建了自定义ImageConverter：

[ValueConversion(typeof(Uri), typeof(BitmapImage))]
public class ImageConverter : IValueConverter
{
    public ImageConverter()
    {
    }
    public object Convert(object value, Type targetType,
                      object parameter, CultureInfo culture)
    {
        try
        {
            if(value == null)
            {
                return null;
            }
            var image = new BitmapImage();
            image.BeginInit();
            image.UriSource = value is Uri ? (Uri)value : new Uri(value.ToString());
            image.CacheOption = BitmapCacheOption.OnLoad;
            image.EndInit();
            return image;               
        }
        catch
        {
            return null;
        }
    }

    public object ConvertBack(object value, Type targetType,
                              object parameter, CultureInfo culture)
    {
        throw new NotSupportedException("Convert back function is not supported");
    }
}

和XAML：

<ImageBrush ImageSource="{Binding Path=Value.Image, Converter={StaticResource imageConverter}}">
</ImageBrush>

C＃Wpf自定义转换器已创建但未调用

1 个答案: