Question

I’m able to convert a byte[] to an image:

byte[] myByteArray = ...;  // ByteArray to be converted

MemoryStream ms = new MemoryStream(my);
BitmapImage bi = new BitmapImage();
bi.SetSource(ms);

Image img = new Image();
img.Source = bi;

But I’m not able to convert the Image back to a byte[]!
I found in the Internet a solution, that works for WPF:

var bmp = img.Source as BitmapImage;
int height = bmp.PixelHeight;
int width  = bmp.PixelWidth;
int stride = width * ((bmp.Format.BitsPerPixel + 7) / 8);

byte[] bits = new byte[height * stride];
bmp.CopyPixels(bits, stride, 0);

The Silverlight libary is so tiny that the class BitmapImage has no property called Format!

Has anybody an idea which solves my problem.

I searched in the internet for a long time to find a solution, but there are is no solution, which works in silverlight!

Thanks!

Answer 1

(the bits per pixel method you are missing just details how the color information is stored per pixel)

As anthony suggested, a WriteableBitmap would be the easiest way – check out http://kodierer.blogspot.com/2009/11/convert-encode-and-decode-silverlight.html for a method to get an argb byte array out :

public static byte[] ToByteArray(this WriteableBitmap bmp)
{
   // Init buffer
   int w = bmp.PixelWidth;
   int h = bmp.PixelHeight;
   int[] p = bmp.Pixels;
   int len = p.Length;
   byte[] result = new byte[4 * w * h];

   // Copy pixels to buffer
   for (int i = 0, j = 0; i < len; i++, j += 4)
  {
      int color = p[i];
      result[j + 0] = (byte)(color >> 24); // A
      result[j + 1] = (byte)(color >> 16); // R
      result[j + 2] = (byte)(color >> 8);  // G
      result[j + 3] = (byte)(color);       // B
   }

    return result;
}