/// <summary>
/// <p>Decodes a QR Code represented as a {@link BitMatrix}. A 1 or "true" is taken to mean a black module.</p>
/// </summary>
/// <param name="bits">booleans representing white/black QR Code modules</param>
/// <param name="hints">decoding hints that should be used to influence decoding</param>
/// <returns>
/// text and bytes encoded within the QR Code
/// </returns>
public DecoderResult Decode(BitMatrix bits)
{
// Construct a parser and read version, error-correction level
var parser = BitMatrixParser.CreateBitMatrixParser(bits);
if (parser == null)
{
return(null);
}
var result = Decode(parser);
if (result == null)
{
// Revert the bit matrix
parser.Remask();
// Will be attempting a mirrored reading of the version and format info.
parser.SetMirror(true);
// Preemptively read the version.
var version = parser.ReadVersion();
if (version == null)
{
return(null);
}
// Preemptively read the format information.
var formatinfo = parser.ReadFormatInformation();
if (formatinfo == null)
{
return(null);
}
/*
* Since we're here, this means we have successfully detected some kind
* of version and format information when mirrored. This is a good sign,
* that the QR code may be mirrored, and we should try once more with a
* mirrored content.
*/
// Prepare for a mirrored reading.
parser.Mirror();
result = Decode(parser);
if (result != null)
{
// Success! Notify the caller that the code was mirrored.
result.Other = new QRCodeDecoderMetaData(true);
}
}
return(result);
}
private DecoderResult Decode(BitMatrixParser parser)
{
Version version = parser.ReadVersion();
if (version == null)
{
return(null);
}
var formatinfo = parser.ReadFormatInformation();
if (formatinfo == null)
{
return(null);
}
ErrorCorrectionLevel ecLevel = formatinfo.ErrorCorrectionLevel;
// Read codewords
byte[] codewords = parser.ReadCodewords();
if (codewords == null)
{
return(null);
}
// Separate into data blocks
DataBlock[] dataBlocks = DataBlock.GetDataBlocks(codewords, version, ecLevel);
// Count total number of data bytes
int totalBytes = 0;
foreach (var dataBlock in dataBlocks)
{
totalBytes += dataBlock.NumDataCodewords;
}
byte[] resultBytes = new byte[totalBytes];
int resultOffset = 0;
// Error-correct and copy data blocks together into a stream of bytes
foreach (var dataBlock in dataBlocks)
{
byte[] codewordBytes = dataBlock.Codewords;
int numDataCodewords = dataBlock.NumDataCodewords;
if (!CorrectErrors(codewordBytes, numDataCodewords))
{
return(null);
}
for (int i = 0; i < numDataCodewords; i++)
{
resultBytes[resultOffset++] = codewordBytes[i];
}
}
// Decode the contents of that stream of bytes
return(DecodedBitStreamParser.Decode(resultBytes, version, ecLevel));
}