Windows Phone 8.1 Runtime - Image to byte[] and Vice Versa

Question

For my application, I am trying to convert an WriteableBitmap to byte[] to store in the database, and then from byte[] to BitmapImage to display back to the user.

My current methods that so far, produce no results:

public byte[] ConvertBitmapToByteArray(WriteableBitmap bitmap)
{
    using (Stream stream = bitmap.PixelBuffer.AsStream())
    using (MemoryStream memoryStream = new MemoryStream())
    {
        stream.CopyTo(memoryStream);
        return memoryStream.ToArray();
    }
}

To convert from byte array to BitmapImage, I use:

using (InMemoryRandomAccessStream ms = new InMemoryRandomAccessStream())
{

    using (DataWriter writer = new DataWriter(ms.GetOutputStreamAt(0)))
    {
        writer.WriteBytes((byte[])buffer);
        writer.StoreAsync().GetResults();
    }


    var image = new BitmapImage();
    image.SetSource(ms);
    imageByteTest.Source = image;
}

There is good documentation for Silverlight applications I have found, but very little in the way for Windows Store Universal Runtime Applications. Where are these methods going wrong?

score 0 · Answer 1 · answered Dec 03 '15 at 21:11

0

You might want to take a look at the WriteableBitmapEx library which contains some extensions to WriteableBitmap, as well as some core features like your conversion of WriteableBitmap to byte array and vice versa.

answered Dec 03 '15 at 21:11

James Croft

1,680
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25

score 0 · Answer 2 · answered Dec 04 '15 at 14:22

I wrote a converter for ByteArrayToBitmapImage:

 public object Convert(object value, Type targetType, object parameter, string language)
    {
        var byteArray = value as byte[];
        var bitmapImage = new BitmapImage();
        Window.Current.Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
            {
                using (var stream = new MemoryStream(byteArray))
                {
                    bitmapImage.SetSourceAsync(stream.AsRandomAccessStream());
                }
            });

        return bitmapImage;

    }

And byte[] -> WriteableBitmap

  public static WriteableBitmap PrepareWritableBitmap(Size size, byte[] pixels)
    {
        uint height = (uint)Math.Floor(size.Height);
        uint width = (uint)Math.Floor(size.Width);

        WriteableBitmap bmp = new WriteableBitmap((int)width, (int)height);
        Stream pixStream = bmp.PixelBuffer.AsStream();
        pixStream.Write(pixels, 0, (int)(width * height * 4));
        //4 is a channel number for RGBA, for RGB is 3 channels
        return bmp;
    }

Windows Phone 8.1 Runtime - Image to byte[] and Vice Versa

2 Answers2