X-Git-Url: http://git.rot13.org/?a=blobdiff_plain;f=core%2Fsrc%2Fcom%2Fgoogle%2Fzxing%2Fqrcode%2Fdecoder%2FFormatInformation.java;h=1b76b0de56e39f2fe0640541fb8a0ea8e1b1fd46;hb=9ba879aa77a14e6a3d42b59c670937eeb64c706e;hp=299768c2027ce64b355ee2c28f33eb8cb1b363c3;hpb=dc1536a0f541ca59529a2078bd51296e3e0dfef0;p=zxing.git

diff --git a/core/src/com/google/zxing/qrcode/decoder/FormatInformation.java b/core/src/com/google/zxing/qrcode/decoder/FormatInformation.java
index 299768c2..1b76b0de 100644
--- a/core/src/com/google/zxing/qrcode/decoder/FormatInformation.java
+++ b/core/src/com/google/zxing/qrcode/decoder/FormatInformation.java
@@ -96,39 +96,51 @@ final class FormatInformation {
   }
 
   /**
-   * @param rawFormatInfo
-   * @return
+   * @param maskedFormatInfo1 format info indicator, with mask still applied
+   * @param maskedFormatInfo2 second copy of same info; both are checked at the same time
+   *  to establish best match
+   * @return information about the format it specifies, or <code>null</code>
+   *  if doesn't seem to match any known pattern
    */
-  static FormatInformation decodeFormatInformation(int rawFormatInfo) {
-    FormatInformation formatInfo = doDecodeFormatInformation(rawFormatInfo);
+  static FormatInformation decodeFormatInformation(int maskedFormatInfo1, int maskedFormatInfo2) {
+    FormatInformation formatInfo = doDecodeFormatInformation(maskedFormatInfo1, maskedFormatInfo2);
     if (formatInfo != null) {
       return formatInfo;
     }
     // Should return null, but, some QR codes apparently
-    // do not mask this info. Try again, first masking the raw bits so
-    // the function will unmask
-    return doDecodeFormatInformation(rawFormatInfo ^ FORMAT_INFO_MASK_QR);
+    // do not mask this info. Try again by actually masking the pattern
+    // first
+    return doDecodeFormatInformation(maskedFormatInfo1 ^ FORMAT_INFO_MASK_QR,
+                                     maskedFormatInfo2 ^ FORMAT_INFO_MASK_QR);
   }
 
-  private static FormatInformation doDecodeFormatInformation(int rawFormatInfo) {
-    // Unmask:
-    int unmaskedFormatInfo = rawFormatInfo ^ FORMAT_INFO_MASK_QR;
+  private static FormatInformation doDecodeFormatInformation(int maskedFormatInfo1, int maskedFormatInfo2) {
     // Find the int in FORMAT_INFO_DECODE_LOOKUP with fewest bits differing
     int bestDifference = Integer.MAX_VALUE;
     int bestFormatInfo = 0;
     for (int i = 0; i < FORMAT_INFO_DECODE_LOOKUP.length; i++) {
       int[] decodeInfo = FORMAT_INFO_DECODE_LOOKUP[i];
       int targetInfo = decodeInfo[0];
-      if (targetInfo == unmaskedFormatInfo) {
+      if (targetInfo == maskedFormatInfo1 || targetInfo == maskedFormatInfo2) {
         // Found an exact match
         return new FormatInformation(decodeInfo[1]);
       }
-      int bitsDifference = numBitsDiffering(unmaskedFormatInfo, targetInfo);
+      int bitsDifference = numBitsDiffering(maskedFormatInfo1, targetInfo);
       if (bitsDifference < bestDifference) {
         bestFormatInfo = decodeInfo[1];
         bestDifference = bitsDifference;
       }
+      if (maskedFormatInfo1 != maskedFormatInfo2) {
+        // also try the other option
+        bitsDifference = numBitsDiffering(maskedFormatInfo2, targetInfo);
+        if (bitsDifference < bestDifference) {
+          bestFormatInfo = decodeInfo[1];
+          bestDifference = bitsDifference;
+        }
+      }
     }
+    // Hamming distance of the 32 masked codes is 7, by construction, so <= 3 bits
+    // differing means we found a match
     if (bestDifference <= 3) {
       return new FormatInformation(bestFormatInfo);
     }