Question

I am referring this http://www.dotnetcurry.com/ShowArticle.aspx?ID=585 to retrieve image from sql server to window phone and had error ArgumentNullException was unhandled when run it at the that higlighted row.

public class ImageConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            byte[] buffer = value as byte[];
            **Stream memStream = new MemoryStream(buffer);**
            WriteableBitmap wbimg = PictureDecoder.DecodeJpeg(memStream);
            return wbimg; 
        }
        public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            return null; 
        }
    }

I had found another similar post had same error with me.
http://forums.create.msdn.com/forums/p/74224/452127.aspx
But don’t understand the coding..Anyone know how to solve the error?

Answer 1

Looks like value is null or is not a byte array.

public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
    WriteableBitmap wbimg = null;

    if (value != null && value is byte[]) {
        byte[] buffer = value as byte[];
        Stream memStream = new MemoryStream(buffer);
        wbimg = PictureDecoder.DecodeJpeg(memStream);
    }

    return wbimg; 
}