无法从Splat.IBitmap加载MemoryStream

Question

我试图通过返回一个Splat.IBitmap将布局数据呈现到与平台无关的位图中，并且输出结果有困难。我的WPF平台代码如下所示：

MemoryStream stream = new MemoryStream();
try
{
    RenderTargetBitmap target = new RenderTargetBitmap(1024, 1024, 300, 300, PixelFormats.Default);
    PreviewView preview = new PreviewView();  // this does sizing and placement

    target.Render(preview);

    previewViewModel.Dispose();
    BitmapEncoder encoder = new BmpBitmapEncoder();
    encoder.Frames.Add(BitmapFrame.Create(target));
    encoder.Save(stream);
    stream.Flush();

    IBitmap bitmap = BitmapLoader.Current.Load(stream, 1024, 1024).Result;
    stream.Dispose();

    return bitmap;
}
catch (Exception e)
{
    // TODO: log error
    return null;
}
finally
{
    stream.Dispose();
}

我一直在BitmapLoader.Current.Load call.The上点击一个NotSupportedException，内部例外是一个带有消息No imaging component suitable to complete this operation was found.的NotSupportedException，我没有找到任何相关的文档来解释这意味着什么或者我做错了什么。作为一种测试，我尝试将位图编码器保存到一个FileStream中，它工作得很好。

编辑

有人指出，这个问题可能是对this issue的重复。它们当然是相关的，但在这种情况下，我想知道为什么保存到MemoryStream中不能创建FileStream工作的有效图像数据。

编辑2

应要求，以下是我在输出中看到的例外情况：

Exception thrown: 'System.NotSupportedException' in PresentationCore.dll
Exception thrown: 'System.NotSupportedException' in PresentationCore.dll
Exception thrown: 'System.AggregateException' in mscorlib.dll

NotSupportedException的内部AggregateException具有以下消息和堆栈跟踪：

No imaging component suitable to complete this operation was found.
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.BitmapImage.FinalizeCreation()
at System.Windows.Media.Imaging.BitmapImage.EndInit()
at Splat.PlatformBitmapLoader.withInit(BitmapImage source, Action`1 block) in y:\\code\\paulcbetts\\splat\\Splat\\Xaml\\Bitmaps.cs:line 80
at Splat.PlatformBitmapLoader.<>c__DisplayClass2.<Load>b__0() in y:\\code\\paulcbetts\\splat\\Splat\\Xaml\\Bitmaps.cs:line 25
at System.Threading.Tasks.Task`1.InnerInvoke()
at System.Threading.Tasks.Task.Execute()

虽然该异常内部NotSupportedException只具有此消息，但没有堆栈跟踪：

The component cannot be found. (Exception from HRESULT: 0x88982F50)

Answer 1

这不能回答我最初的问题，所以我不会接受这个正确的答案，但我找到了一个更正确的方法来处理我想要的东西。我写信给一个MemoryStream是因为我认为这是必要的，但我所需要的只是在WPF中看到一个布局好的视图，并获得一个IBitmap，我可以在其他地方使用。事实证明，要做到这一点比我想象的要容易得多：

try
{
    RenderTargetBitmap target = new RenderTargetBitmap(1024, 1024, 300, 300,
        PixelFormats.Default);
    PreviewView preview = new PreviewView();  // this does sizing and placement

    target.Render(preview);

    // HERE IS AN IMPORTANT BIT. This allows me to access the RenderTargetBitmap from 
    // another thread, for example if calling IBitmap.Save() which happens on another
    // in a separate Task
    target.Freeze();

    previewViewModel.Dispose();

    // HERE IS ANOTHER IMPORTANT BIT. There's no need to capture a frame and save to a 
    // Stream through an Encoder. Splat lets you create bitmaps from a native
    // implementation
    IBitmap bitmap = target.FromNative();

    return bitmap;
}
catch (Exception e)
{
    // TODO: log error
    return null;
}