Take more advantage of TRY_HARDER

[zxing.git] / core / src / com / google / zxing / oned / MultiFormatUPCEANReader.java

diff --git a/core/src/com/google/zxing/oned/MultiFormatUPCEANReader.java b/core/src/com/google/zxing/oned/MultiFormatUPCEANReader.java
index f7c9b7d..dff4ad5 100644 (file)
--- a/core/src/com/google/zxing/oned/MultiFormatUPCEANReader.java
+++ b/core/src/com/google/zxing/oned/MultiFormatUPCEANReader.java
@@ -16,10 +16,15 @@
 
 package com.google.zxing.oned;
 
+import com.google.zxing.BarcodeFormat;
+import com.google.zxing.DecodeHintType;
 import com.google.zxing.ReaderException;
 import com.google.zxing.Result;
 import com.google.zxing.common.BitArray;
 
+import java.util.Hashtable;
+import java.util.Vector;
+
 /**
  * <p>A reader that can read all available UPC/EAN formats. If a caller wants to try to
  * read all such formats, it is most efficent to use this implementation rather than invoke
@@ -29,26 +34,59 @@ import com.google.zxing.common.BitArray;
  */
 public final class MultiFormatUPCEANReader extends AbstractOneDReader {
 
-  /**
-   * Reader implementations to which this implementation delegates, in the order
-   * they will be attempted. Order is important.
-   */
-  private final UPCEANReader[] readers = new UPCEANReader[] {
-      new EAN13Reader(), new UPCAReader(), new EAN8Reader(), new UPCEReader()
-  };
+  public Result decodeRow(int rowNumber, BitArray row, Hashtable hints) throws ReaderException {
+    Hashtable possibleFormats = hints == null ? null : (Hashtable) hints.get(DecodeHintType.POSSIBLE_FORMATS);
+    Vector readers = new Vector();
+    if (possibleFormats != null) {
+      if (possibleFormats.contains(BarcodeFormat.EAN_13)) {
+        readers.addElement(new EAN13Reader());
+      }
+      if (possibleFormats.contains(BarcodeFormat.UPC_A)) {
+        readers.addElement(new UPCAReader());
+      }
+      if (possibleFormats.contains(BarcodeFormat.EAN_8)) {
+        readers.addElement(new EAN8Reader());
+      }
+      if (possibleFormats.contains(BarcodeFormat.UPC_E)) {
+        readers.addElement(new UPCEReader());
+      }
+    }
+    if (readers.isEmpty()) {
+      readers.addElement(new EAN13Reader());      
+      readers.addElement(new UPCAReader());
+      readers.addElement(new EAN8Reader());
+      readers.addElement(new UPCEReader());
+    }
 
-  public Result decodeRow(int rowNumber, BitArray row) throws ReaderException {
     // Compute this location once and reuse it on multiple implementations
     int[] startGuardPattern = AbstractUPCEANReader.findStartGuardPattern(row);
-    ReaderException saved = null;
-    for (int i = 0; i < readers.length; i++) {
+    for (int i = 0; i < readers.size(); i++) {
+      UPCEANReader reader = (UPCEANReader) readers.elementAt(i);
+      Result result;
       try {
-        return readers[i].decodeRow(rowNumber, row, startGuardPattern);
+        result = reader.decodeRow(rowNumber, row, startGuardPattern);
       } catch (ReaderException re) {
-        saved = re;
+        continue;
       }
+      // Special case: a 12-digit code encoded in UPC-A is identical to a "0"
+      // followed by those 12 digits encoded as EAN-13. Each will recognize such a code,
+      // UPC-A as a 12-digit string and EAN-13 as a 13-digit string starting with "0".
+      // Individually these are correct.
+      //
+      // These cases can't be distinguished, so we defer to the UPC-A decoder and
+      // treat this case as a UPC-A code. But if we let the UPC-A decoder look at
+      // symbols first, it will recognize any EAN-13 code as a 12-digit string,
+      // which is wrong. So EAN-13 has to try first.
+      //
+      // Here is, therefore, where we implement this logic:
+      if (result.getBarcodeFormat().equals(BarcodeFormat.EAN_13) &&
+          result.getText().charAt(0) == '0') {
+        return new Result(result.getText().substring(1), result.getResultPoints(), BarcodeFormat.UPC_A);
+      }
+      return result;
     }
-    throw saved;
+
+    throw new ReaderException("No barcode was detected in this image.");
   }
 
 }
\ No newline at end of file