/// <summary>
/// Reads the <see cref="Encoding"/> from the specified XML <see cref="Stream"/>. If an encoding cannot be resolved, <paramref name="defaultEncoding"/> encoding is assumed for the <see cref="Encoding"/>.
/// </summary>
/// <param name="value">The <see cref="Stream"/> to resolve an <see cref="Encoding"/> object from.</param>
/// <param name="defaultEncoding">The preferred default <see cref="Encoding"/> to use if an encoding cannot be resolved automatically.</param>
/// <returns>An <see cref="Encoding"/> object equivalent to the encoding used in the <paramref name="value"/>, or <paramref name="defaultEncoding"/> if unable to resolve the encoding.</returns>
public static Encoding ReadEncoding(Stream value, Encoding defaultEncoding)
{
if (value == null)
{
throw new ArgumentNullException(nameof(value));
}
Encoding encoding;
if (!EncodingUtility.TryParse(value, out encoding))
{
long startingPosition = -1;
if (value.CanSeek)
{
startingPosition = value.Position;
value.Position = 0;
}
XmlDocument document = new XmlDocument();
document.Load(value);
if (document.FirstChild.NodeType == XmlNodeType.XmlDeclaration)
{
XmlDeclaration declaration = (XmlDeclaration)document.FirstChild;
if (!string.IsNullOrEmpty(declaration.Encoding))
{
encoding = Encoding.GetEncoding(declaration.Encoding);
}
}
if (value.CanSeek)
{
value.Seek(startingPosition, SeekOrigin.Begin);
}
}
return(encoding ?? defaultEncoding);
}