【备忘】想从Bitmap得到BitmapSource还真麻烦

public static class Imaging
{
    public static BitmapSource CreateBitmapSourceFromBitmap(Bitmap bitmap)
    {
        if (bitmap == null)
            throw new ArgumentNullException("bitmap");
                
        if (Application.Current.Dispatcher == null)
            return null; // Is it possible?
                
        try
        {
            using (MemoryStream memoryStream = new MemoryStream())
            {
                // You need to specify the image format to fill the stream. 
                // I'm assuming it is PNG
                bitmap.Save(memoryStream, ImageFormat.Png);
                memoryStream.Seek(0, SeekOrigin.Begin);
                
                // Make sure to create the bitmap in the UI thread
                if (InvokeRequired)
                    return (BitmapSource)Application.Current.Dispatcher.Invoke(
                        new Func(CreateBitmapSourceFromBitmap),
                        DispatcherPriority.Normal,
                        memoryStream);
                
                return CreateBitmapSourceFromBitmap(memoryStream);
            }
        }
        catch (Exception)
        {
            return null;
        }
    }
                
    private static bool InvokeRequired
    {
        get { return Dispatcher.CurrentDispatcher != Application.Current.Dispatcher; }
    }
                
    private static BitmapSource CreateBitmapSourceFromBitmap(Stream stream)
    {
        BitmapDecoder bitmapDecoder = BitmapDecoder.Create(
            stream,
            BitmapCreateOptions.PreservePixelFormat,
            BitmapCacheOption.OnLoad);
                
        // This will disconnect the stream from the image completely...
        WriteableBitmap writable = new WriteableBitmap(bitmapDecoder.Frames.Single());
        writable.Freeze();
                
        return writable;
    }
}