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

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?

Answer 1

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.

Answer 2

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;
}