/// <summary>
/// Detects the best <see cref="Encoding"/> to use to convert the data in the supplied stream to Unicode, and returns it.
/// </summary>
/// <param name="stream">The stream to detect the character encoding for.</param>
/// <returns>The best <see cref="Encoding"/> object to be used to decode text from <paramref name="stream"/>
/// into Unicode, or <c>null</c> if the best encoding can't be detected.</returns>
/// <remarks>See <a href="http://code.logos.com/blog/2010/05/detecting_the_character_encoding_of_a_file.html">Detecting the Character Encoding of a File</a>.</remarks>
public static Encoding DetectBestEncoding(Stream stream)
{
// check parameter validity
if (stream == null)
{
throw new ArgumentNullException("stream");
}
if (!stream.CanRead)
{
throw new NotSupportedException("'stream' must be readable.");
}
if (!stream.CanSeek)
{
throw new NotSupportedException("'stream' must be seekable.");
}
// the encoding that was detected, or null on failure
Encoding encoding = null;
// MLang will move the stream pointer; remember its original position
long position = stream.Position;
// allocate a number of DetectEncodingInfo structures for MLang to fill in
DetectEncodingInfo[] infos = new DetectEncodingInfo[8];
int infoCount = infos.Length;
// allow MLang to seek to the "beginning" (i.e., current position) of the stream by rebasing it
using (RebasedStream rebased = new RebasedStream(stream))
{
try
{
// try to create MLang object
IMultiLanguage2 multiLanguage = (IMultiLanguage2) new MultiLanguage();
// wrap input stream with an IStream
ManagedIStream istream = new ManagedIStream(rebased);
// detect the code page
int hresult = multiLanguage.DetectCodepageInIStream(MultiLanguageDetectCodePage.None, 0, istream, ref infos[0], ref infoCount);
GC.KeepAlive(istream);
if (infoCount > 0 && (hresult == Win32.S_OK || hresult == Win32.S_FALSE))
{
// take the best code page that was found
int nCodePage = (int)infos.Take(infoCount).OrderByDescending(i => i.nConfidence).Select(i => i.nCodePage).FirstOrDefault();
encoding = Encoding.GetEncoding(nCodePage);
}
}
catch (COMException)
{
// failure
}
}
// reset the stream back to its input position for the caller
stream.Position = position;
// return detected encoding (or null for failure)
return(encoding);
}
/// <summary>
/// Detects the best <see cref="Encoding"/> to use to convert the data in the supplied stream to Unicode, and returns it.
/// </summary>
/// <param name="stream">The stream to detect the character encoding for.</param>
/// <returns>The best <see cref="Encoding"/> object to be used to decode text from <paramref name="stream"/>
/// into Unicode, or <c>null</c> if the best encoding can't be detected.</returns>
/// <remarks>See <a href="http://code.logos.com/blog/2010/05/detecting_the_character_encoding_of_a_file.html">Detecting the Character Encoding of a File</a>.</remarks>
public static Encoding DetectBestEncoding(Stream stream)
{
// check parameter validity
if (stream == null)
throw new ArgumentNullException("stream");
if (!stream.CanRead)
throw new NotSupportedException("'stream' must be readable.");
if (!stream.CanSeek)
throw new NotSupportedException("'stream' must be seekable.");
// the encoding that was detected, or null on failure
Encoding encoding = null;
// MLang will move the stream pointer; remember its original position
long position = stream.Position;
// allocate a number of DetectEncodingInfo structures for MLang to fill in
DetectEncodingInfo[] infos = new DetectEncodingInfo[8];
int infoCount = infos.Length;
// allow MLang to seek to the "beginning" (i.e., current position) of the stream by rebasing it
using (RebasedStream rebased = new RebasedStream(stream))
{
try
{
// try to create MLang object
IMultiLanguage2 multiLanguage = (IMultiLanguage2) new MultiLanguage();
// wrap input stream with an IStream
ManagedIStream istream = new ManagedIStream(rebased);
// detect the code page
int hresult = multiLanguage.DetectCodepageInIStream(MultiLanguageDetectCodePage.None, 0, istream, ref infos[0], ref infoCount);
GC.KeepAlive(istream);
if (infoCount > 0 && (hresult == Win32.S_OK || hresult == Win32.S_FALSE))
{
// take the best code page that was found
int nCodePage = (int) infos.Take(infoCount).OrderByDescending(i => i.nConfidence).Select(i => i.nCodePage).FirstOrDefault();
encoding = Encoding.GetEncoding(nCodePage);
}
}
catch (COMException)
{
// failure
}
}
// reset the stream back to its input position for the caller
stream.Position = position;
// return detected encoding (or null for failure)
return encoding;
}
