internal static DecoderResult Decode(byte[] bytes,
Version version,
ErrorCorrectionLevel ecLevel,
IDictionary <DecodeHintType, object> hints)
{
var bits = new BitSource(bytes);
var result = new StringBuilder(50);
var byteSegments = new List <byte[]>(1);
var symbolSequence = -1;
var parityData = -1;
try
{
CharacterSetECI currentCharacterSetECI = null;
bool fc1InEffect = false;
Mode mode;
do
{
// While still another segment to read...
if (bits.available() < 4)
{
// OK, assume we're done. Really, a TERMINATOR mode should have been recorded here
mode = Mode.TERMINATOR;
}
else
{
try
{
mode = Mode.ForBits(bits.readBits(4)); // mode is encoded by 4 bits
hints[DecodeHintType.VERSION] = mode;
}
catch (ArgumentException)
{
return(null);
}
}
switch (mode.Name)
{
case Mode.Names.TERMINATOR:
break;
case Mode.Names.FNC1_FIRST_POSITION:
case Mode.Names.FNC1_SECOND_POSITION:
// We do little with FNC1 except alter the parsed result a bit according to the spec
fc1InEffect = true;
break;
case Mode.Names.STRUCTURED_APPEND:
if (bits.available() < 16)
{
return(null);
}
// not really supported; but sequence number and parity is added later to the result metadata
// Read next 8 bits (symbol sequence #) and 8 bits (parity data), then continue
symbolSequence = bits.readBits(8);
parityData = bits.readBits(8);
break;
case Mode.Names.ECI:
// Count doesn't apply to ECI
int value = parseECIValue(bits);
currentCharacterSetECI = CharacterSetECI.getCharacterSetECIByValue(value);
if (currentCharacterSetECI == null)
{
return(null);
}
break;
case Mode.Names.HANZI:
// First handle Hanzi mode which does not start with character count
//chinese mode contains a sub set indicator right after mode indicator
int subset = bits.readBits(4);
int countHanzi = bits.readBits(mode.GetCharacterCountBits(version));
if (subset == GB2312_SUBSET)
{
if (!decodeHanziSegment(bits, result, countHanzi))
{
return(null);
}
}
break;
default:
// "Normal" QR code modes:
// How many characters will follow, encoded in this mode?
int count = bits.readBits(mode.GetCharacterCountBits(version));
switch (mode.Name)
{
case Mode.Names.NUMERIC:
if (!decodeNumericSegment(bits, result, count))
{
return(null);
}
break;
case Mode.Names.ALPHANUMERIC:
if (!decodeAlphanumericSegment(bits, result, count, fc1InEffect))
{
return(null);
}
break;
case Mode.Names.BYTE:
if (!decodeByteSegment(bits, result, count, currentCharacterSetECI, byteSegments, hints))
{
return(null);
}
break;
case Mode.Names.KANJI:
if (!decodeKanjiSegment(bits, result, count))
{
return(null);
}
break;
default:
return(null);
}
break;
}
} while (mode != Mode.TERMINATOR);
}
catch (ArgumentException)
{
// from readBits() calls
return(null);
}
return(new DecoderResult(bytes,
result.ToString(),
byteSegments.Count == 0 ? null : byteSegments,
ecLevel == null ? null : ecLevel.ToString(),
symbolSequence, parityData));
}
