error in my byte[] to WPF BitmapImage conversion?

问题:

I'm saving a BitmapImage to a byte[] for saving in a DB. I'm pretty sure the data is being saved and retrieved accurately so it's not an issue there.

On my byte[] to BitmapImage conversion I keep getting an exception of "System.NotSupportedException: No imaging component suitable to complete this operation was found."

Can anyone see what I'm doing wrong with my two functions here?

  private Byte[] convertBitmapImageToBytestream(BitmapImage bi)
  {
     int height = bi.PixelHeight;
     int width = bi.PixelWidth;
     int stride = width * ((bi.Format.BitsPerPixel + 7) / 8);

     Byte[] bits = new Byte[height * stride];
     bi.CopyPixels(bits, stride, 0);

     return bits;
  }

  public BitmapImage convertByteToBitmapImage(Byte[] bytes)
  {
     MemoryStream stream = new MemoryStream(bytes);
     stream.Position = 0;
     BitmapImage bi = new BitmapImage();
     bi.BeginInit();
     bi.StreamSource = stream;
     bi.EndInit();
     return bi;
  }

回答1:

Does this StackOverflow question helps?

byte[] to BitmapImage in silverlight

EDIT:

Try this, not sure it will work:

public BitmapImage convertByteToBitmapImage(Byte[] bytes)
{
    MemoryStream stream = new MemoryStream(bytes);
    stream.Position = 0;
    BitmapImage bi = new BitmapImage();
    bi.BeginInit();
    bi.CacheOption = BitmapCacheOption.OnLoad;
    bi.DecodePixelWidth = ??; // Width of the image
    bi.StreamSource = stream;
    bi.EndInit();
    return bi;
}

UPDATE 2:

I found these:

Load a byte[] into an Image at Runtime

BitmapImage from byte[] on a non UIThread

Apart from that, I don't know.

回答2:

How do you know that the byte[] format you are creating is what the BI expects in the Stream? Why don't you use the BitmapImage.StreamSource to create the byte[] that you save? Then you know the format will be compatible.

http://www.codeproject.com/KB/vb/BmpImage2ByteArray.aspx

http://social.msdn.microsoft.com/forums/en-US/wpf/thread/8327dd31-2db1-4daa-a81c-aff60b63fee6/

[I did not try any of this code, but you can]

回答3:

Turns out the bitmapimage CopyPixels isn't right. I take the output of the bitmapimage and convert it to something usable in this case a jpg.

public static Byte[] convertBitmapImageToBytestream(BitmapImage bi)
  {
     MemoryStream memStream = new MemoryStream();
     JpegBitmapEncoder encoder = new JpegBitmapEncoder();
     encoder.Frames.Add(BitmapFrame.Create(bi));
     encoder.Save(memStream);
     byte[] bytestream = memStream.GetBuffer();
     return bytestream;
  }