Use barcode-specific min height when searching for stop pattern (fixes #1641) (#1642)

4 files changed, 17 insertions, 8 deletions

diff --git a/core/src/main/java/com/google/zxing/pdf417/detector/Detector.java b/core/src/main/java/com/google/zxing/pdf417/detector/Detector.java
index e629beaf0..cda7f650f 100644
--- a/core/src/main/java/com/google/zxing/pdf417/detector/Detector.java
+++ b/core/src/main/java/com/google/zxing/pdf417/detector/Detector.java
@@ -40,7 +40,8 @@ public final class Detector {
   private static final int[] INDEXES_START_PATTERN = {0, 4, 1, 5};
   private static final int[] INDEXES_STOP_PATTERN = {6, 2, 7, 3};
   private static final float MAX_AVG_VARIANCE = 0.42f;
-  private static final float MAX_INDIVIDUAL_VARIANCE = 0.7f;
+  private static final float MAX_INDIVIDUAL_VARIANCE = 0.8f;
+  private static final float MAX_STOP_PATTERN_HEIGHT_VARIANCE = 0.5f;
 
   // B S B S B S B S Bar/Space pattern
   // 11111111 0 1 0 1 0 1 000
@@ -178,14 +179,20 @@ public final class Detector {
     int width = matrix.getWidth();
 
     ResultPoint[] result = new ResultPoint[8];
-    copyToResult(result, findRowsWithPattern(matrix, height, width, startRow, startColumn, START_PATTERN),
+    int minHeight = BARCODE_MIN_HEIGHT;
+    copyToResult(result, findRowsWithPattern(matrix, height, width, startRow, startColumn, minHeight, START_PATTERN),
         INDEXES_START_PATTERN);
 
     if (result[4] != null) {
       startColumn = (int) result[4].getX();
       startRow = (int) result[4].getY();
+      if (result[5] != null) {
+        int endRow = (int) result[5].getY();
+        int startPatternHeight = endRow - startRow;
+        minHeight = (int) Math.max(startPatternHeight * MAX_STOP_PATTERN_HEIGHT_VARIANCE, BARCODE_MIN_HEIGHT);
+      }
     }
-    copyToResult(result, findRowsWithPattern(matrix, height, width, startRow, startColumn, STOP_PATTERN),
+    copyToResult(result, findRowsWithPattern(matrix, height, width, startRow, startColumn, minHeight, STOP_PATTERN),
         INDEXES_STOP_PATTERN);
     return result;
   }
@@ -201,6 +208,7 @@ public final class Detector {
                                                    int width,
                                                    int startRow,
                                                    int startColumn,
+                                                   int minHeight,
                                                    int[] pattern) {
     ResultPoint[] result = new ResultPoint[4];
     boolean found = false;
@@ -251,7 +259,7 @@ public final class Detector {
       result[2] = new ResultPoint(previousRowLoc[0], stopRow);
       result[3] = new ResultPoint(previousRowLoc[1], stopRow);
     }
-    if (stopRow - startRow < BARCODE_MIN_HEIGHT) {
+    if (stopRow - startRow < minHeight) {
       Arrays.fill(result, null);
     }
     return result;
diff --git a/core/src/test/java/com/google/zxing/pdf417/PDF417BlackBox1TestCase.java b/core/src/test/java/com/google/zxing/pdf417/PDF417BlackBox1TestCase.java
index b86222d24..c4060cab6 100644
--- a/core/src/test/java/com/google/zxing/pdf417/PDF417BlackBox1TestCase.java
+++ b/core/src/test/java/com/google/zxing/pdf417/PDF417BlackBox1TestCase.java
@@ -29,10 +29,10 @@ public final class PDF417BlackBox1TestCase extends AbstractBlackBoxTestCase {
 
   public PDF417BlackBox1TestCase() {
     super("src/test/resources/blackbox/pdf417-1", new MultiFormatReader(), BarcodeFormat.PDF_417);
-    addTest(11, 11, 0.0f);
-    addTest(11, 11, 90.0f);
-    addTest(11, 11, 180.0f);
-    addTest(11, 11, 270.0f);
+    addTest(12, 12, 0.0f);
+    addTest(12, 12, 90.0f);
+    addTest(12, 12, 180.0f);
+    addTest(12, 12, 270.0f);
   }
 
 }
diff --git a/core/src/test/resources/blackbox/pdf417-1/13.png b/core/src/test/resources/blackbox/pdf417-1/13.png
new file mode 100644
index 000000000..3251b95d3
--- /dev/null
+++ b/core/src/test/resources/blackbox/pdf417-1/13.png
diff --git a/core/src/test/resources/blackbox/pdf417-1/13.txt b/core/src/test/resources/blackbox/pdf417-1/13.txt
new file mode 100644
index 000000000..0ee4e3228
--- /dev/null
+++ b/core/src/test/resources/blackbox/pdf417-1/13.txt
@@ -0,0 +1 @@
++ABCDEFGHIJABCDEFGHIJABCDEFGHIJABBCDEV
\ No newline at end of file