Function SampleMQR

czxing/src/main/cpp/zxing/src/qrcode/QRDetector.cpp:593–652

}

DetectorResult SampleMQR(const BitMatrix& image, const ConcentricPattern& fp)
{
	auto fpQuad = FindConcentricPatternCorners(image, fp, fp.size, 2);
	if (!fpQuad)
		return {};

	auto srcQuad = Rectangle(7, 7, 0.5);

#if defined(_MSVC_LANG) // TODO: see MSVC issue https://developercommunity.visualstudio.com/t/constexpr-object-is-unable-to-be-used-as/10035065
	static
#else
	constexpr
#endif
		const PointI FORMAT_INFO_COORDS[] = {{0, 8}, {1, 8}, {2, 8}, {3, 8}, {4, 8}, {5, 8}, {6, 8}, {7, 8}, {8, 8},
											 {8, 7}, {8, 6}, {8, 5}, {8, 4}, {8, 3}, {8, 2}, {8, 1}, {8, 0}};

	FormatInformation bestFI;
	PerspectiveTransform bestPT;

	for (int i = 0; i < 4; ++i) {
		auto mod2Pix = PerspectiveTransform(srcQuad, RotatedCorners(*fpQuad, i));

		auto check = [&](int i, bool checkOne) {
			auto p = mod2Pix(centered(FORMAT_INFO_COORDS[i]));
			return image.isIn(p) && (!checkOne || image.get(p));
		};

		// check that we see both innermost timing pattern modules
		if (!check(0, true) || !check(8, false) || !check(16, true))
			continue;

		int formatInfoBits = 0;
		for (int i = 1; i <= 15; ++i)
			AppendBit(formatInfoBits, image.get(mod2Pix(centered(FORMAT_INFO_COORDS[i]))));

		auto fi = FormatInformation::DecodeMQR(formatInfoBits);
		if (fi.hammingDistance < bestFI.hammingDistance) {
			bestFI = fi;
			bestPT = mod2Pix;
		}
	}

	if (!bestFI.isValid())
		return {};

	const int dim = Version::DimensionOfVersion(bestFI.microVersion, true);

	// check that we are in fact not looking at a corner of a non-micro QRCode symbol
	// we accept at most 1/3rd black pixels in the quite zone (in a QRCode symbol we expect about 1/2).
	int blackPixels = 0;
	for (int i = 0; i < dim; ++i) {
		auto px = bestPT(centered(PointI{i, dim}));
		auto py = bestPT(centered(PointI{dim, i}));
		blackPixels += (image.isIn(px) && image.get(px)) + (image.isIn(py) && image.get(py));
	}
	if (blackPixels > 2 * dim / 3)
		return {};