ITF: fix detection regression

introduced in e3672fd Add test image that checks for support of slanted (non-perpendicular) scanned symbols.
zxing-cpp · Nov 5, 2024 · 8d9aecc · 8d9aecc
1 parent 308f820
commit 8d9aecc
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Showing 6 changed files with 15 additions and 9 deletions.
diff --git a/core/src/oned/ODITFReader.cpp b/core/src/oned/ODITFReader.cpp
@@ -41,31 +41,35 @@ Barcode ITFReader::decodePattern(int rowNumber, PatternView& next, std::unique_p
 	txt.reserve(20);
 
 	while (next.isValid()) {
-		threshold = NarrowWideThreshold(next);
-		if (!threshold.isValid())
+		// look for end-of-symbol
+		if (next[3] > threshold.space * 3)
 			break;
 
 		BarAndSpace<int> digits, numWide;
+		bool bad = false;
 		for (int i = 0; i < 10; ++i) {
-			if (next[i] > threshold[i] * 2)
-				break;
+			bad |= next[i] > threshold[i] * 3 || next[i] < threshold[i] / 3;
 			numWide[i] += next[i] > threshold[i];
 			digits[i] += weights[i/2] * (next[i] > threshold[i]);
 		}
 
-		if (numWide.bar != 2 || numWide.space != 2)
+		if (bad || numWide.bar != 2 || numWide.space != 2)
 			break;
 
 		for (int i = 0; i < 2; ++i)
 			txt.push_back(ToDigit(digits[i] == 11 ? 0 : digits[i]));
 
+		// update threshold to support scanning slanted symbols (scanned non-perpendicular)
+		threshold = NarrowWideThreshold(next);
+
 		next.skipSymbol();
 	}
 
 	next = next.subView(0, 3);
 
 	// Check quiet zone size
-	if (!next.isValid() || !(next.isAtLastBar() || next[3] > minQuietZone * (threshold.bar + threshold.space) / 3))
+	if (!next.isValid() || !threshold.isValid()
+		|| !(next.isAtLastBar() || next[3] > minQuietZone * (threshold.bar + threshold.space) / 3))
 		return {};
 
 	// Check stop pattern

diff --git a/test/blackbox/BlackboxTestRunner.cpp b/test/blackbox/BlackboxTestRunner.cpp
@@ -464,9 +464,9 @@ int runBlackBoxTests(const fs::path& testPathPrefix, const std::set<std::string>
 			{ 3, 5, 180 },
 		}, ReaderOptions().setEanAddOnSymbol(EanAddOnSymbol::Require));
 
-		runTests("itf-1", "ITF", 12, {
-			{ 11, 12, 0   },
-			{ 11, 12, 180 },
+		runTests("itf-1", "ITF", 14, {
+			{ 13, 14, 0   },
+			{ 13, 14, 180 },
 		});
 
 		runTests("itf-2", "ITF", 6, {

diff --git a/test/samples/itf-1/1-slanted.png b/test/samples/itf-1/1-slanted.png
diff --git a/test/samples/itf-1/1-slanted.txt b/test/samples/itf-1/1-slanted.txt
@@ -0,0 +1 @@
+30712345000010
diff --git a/test/samples/itf-1/with-tail.png b/test/samples/itf-1/with-tail.png
diff --git a/test/samples/itf-1/with-tail.txt b/test/samples/itf-1/with-tail.txt
@@ -0,0 +1 @@
+00123456