Add experimental tryDenoise to C API (#952)

This was discussed in #949.

core/src/Barcode.cpp

@@ -155,7 +155,8 @@ void Result::symbol(BitMatrix&& bits)
 
 ImageView Result::symbol() const
 {
-	return _symbol ? ImageView{_symbol->row(0).begin(), _symbol->width(), _symbol->height(), ImageFormat::Lum} : ImageView{};
+	return _symbol && !_symbol->empty() ? ImageView{_symbol->row(0).begin(), _symbol->width(), _symbol->height(), ImageFormat::Lum}
+										: ImageView{};
 }
 
 void Result::zint(unique_zint_symbol&& z)

core/src/BinaryBitmap.cpp

@@ -63,7 +63,7 @@ void BinaryBitmap::invert()
 		auto matrix = const_cast<BitMatrix*>(_cache->matrix.get());
 		matrix->flipAll();
 	}
-	_inverted = true;
+	_inverted = !_inverted;
 }
 
 template <typename F>

core/src/ReadBarcode.cpp

@@ -175,8 +175,12 @@ Barcodes ReadBarcodes(const ImageView& _iv, const ReaderOptions& opts)
 	for (auto&& iv : pyramid.layers) {
 		auto bitmap = CreateBitmap(opts.binarizer(), iv);
 		for (int close = 0; close <= (closedReader ? 1 : 0); ++close) {
-			if (close)
+			if (close) {
+				// if we already inverted the image in the first round, we need to undo that first
+				if (bitmap->inverted())
+					bitmap->invert();
 				bitmap->close();
+			}
 
 			// TODO: check if closing after invert would be beneficial
 			for (int invert = 0; invert <= static_cast<int>(opts.tryInvert() && !close); ++invert) {

core/src/ZXingC.cpp

@@ -281,6 +281,9 @@ ZX_PROPERTY(bool, tryHarder, TryHarder)
 ZX_PROPERTY(bool, tryRotate, TryRotate)
 ZX_PROPERTY(bool, tryInvert, TryInvert)
 ZX_PROPERTY(bool, tryDownscale, TryDownscale)
+#ifdef ZXING_EXPERIMENTAL_API
+	ZX_PROPERTY(bool, tryDenoise, TryDenoise)
+#endif
 ZX_PROPERTY(bool, isPure, IsPure)
 ZX_PROPERTY(bool, returnErrors, ReturnErrors)
 ZX_PROPERTY(int, minLineCount, MinLineCount)

core/src/ZXingC.h

@@ -233,6 +233,9 @@ void ZXing_ReaderOptions_setTryHarder(ZXing_ReaderOptions* opts, bool tryHarder)
 void ZXing_ReaderOptions_setTryRotate(ZXing_ReaderOptions* opts, bool tryRotate);
 void ZXing_ReaderOptions_setTryInvert(ZXing_ReaderOptions* opts, bool tryInvert);
 void ZXing_ReaderOptions_setTryDownscale(ZXing_ReaderOptions* opts, bool tryDownscale);
+#ifdef ZXING_EXPERIMENTAL_API
+	void ZXing_ReaderOptions_setTryDenoise(ZXing_ReaderOptions* opts, bool tryDenoise);
+#endif
 void ZXing_ReaderOptions_setIsPure(ZXing_ReaderOptions* opts, bool isPure);
 void ZXing_ReaderOptions_setReturnErrors(ZXing_ReaderOptions* opts, bool returnErrors);
 void ZXing_ReaderOptions_setFormats(ZXing_ReaderOptions* opts, ZXing_BarcodeFormats formats);
@@ -246,6 +249,9 @@ bool ZXing_ReaderOptions_getTryHarder(const ZXing_ReaderOptions* opts);
 bool ZXing_ReaderOptions_getTryRotate(const ZXing_ReaderOptions* opts);
 bool ZXing_ReaderOptions_getTryInvert(const ZXing_ReaderOptions* opts);
 bool ZXing_ReaderOptions_getTryDownscale(const ZXing_ReaderOptions* opts);
+#ifdef ZXING_EXPERIMENTAL_API
+	bool ZXing_ReaderOptions_getTryDenoise(const ZXing_ReaderOptions* opts);
+#endif
 bool ZXing_ReaderOptions_getIsPure(const ZXing_ReaderOptions* opts);
 bool ZXing_ReaderOptions_getReturnErrors(const ZXing_ReaderOptions* opts);
 ZXing_BarcodeFormats ZXing_ReaderOptions_getFormats(const ZXing_ReaderOptions* opts);