Function Decode

czxing/src/main/cpp/zxing/src/qrcode/QRDecoder.cpp:317–358

}

DecoderResult Decode(const BitMatrix& bits)
{
	const Version* pversion = ReadVersion(bits);
	if (!pversion)
		return FormatError("Invalid version");
	const Version& version = *pversion;

	auto formatInfo = ReadFormatInformation(bits, version.isMicroQRCode());
	if (!formatInfo.isValid())
		return FormatError("Invalid format information");

	// Read codewords
	ByteArray codewords = ReadCodewords(bits, version, formatInfo);
	if (codewords.empty())
		return FormatError("Failed to read codewords");

	// Separate into data blocks
	std::vector<DataBlock> dataBlocks = DataBlock::GetDataBlocks(codewords, version, formatInfo.ecLevel);
	if (dataBlocks.empty())
		return FormatError("Failed to get data blocks");

	// Count total number of data bytes
	const auto op = [](auto totalBytes, const auto& dataBlock){ return totalBytes + dataBlock.numDataCodewords();};
	const auto totalBytes = std::accumulate(std::begin(dataBlocks), std::end(dataBlocks), int{}, op);
	ByteArray resultBytes(totalBytes);
	auto resultIterator = resultBytes.begin();

	// Error-correct and copy data blocks together into a stream of bytes
	for (auto& dataBlock : dataBlocks)
	{
		ByteArray& codewordBytes = dataBlock.codewords();
		int numDataCodewords = dataBlock.numDataCodewords();

		if (!CorrectErrors(codewordBytes, numDataCodewords))
			return ChecksumError();

		resultIterator = std::copy_n(codewordBytes.begin(), numDataCodewords, resultIterator);
	}

	// Decode the contents of that stream of bytes
	return DecodeBitStream(std::move(resultBytes), version, formatInfo.ecLevel).setIsMirrored(formatInfo.isMirrored);
}

} // namespace ZXing::QRCode