Added some comments and fixed up lines over 100 columns.

[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 835504b..502b086 100644 (file)
--- a/core/src/com/google/zxing/oned/MultiFormatUPCEANReader.java
+++ b/core/src/com/google/zxing/oned/MultiFormatUPCEANReader.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2008 Google Inc.
+ * Copyright 2008 ZXing authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -27,21 +27,23 @@ 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
+ * read all such formats, it is most efficient to use this implementation rather than invoke
  * individual readers.</p>
  *
- * @author srowen@google.com (Sean Owen)
+ * @author Sean Owen
  */
 public final class MultiFormatUPCEANReader extends AbstractOneDReader {
 
-  public Result decodeRow(int rowNumber, BitArray row, Hashtable hints) throws ReaderException {
-    Vector possibleFormats = hints == null ? null : (Vector) hints.get(DecodeHintType.POSSIBLE_FORMATS);
-    Vector readers = new Vector();
+  private final Vector readers;
+
+  public MultiFormatUPCEANReader(Hashtable hints) {
+    Vector possibleFormats = hints == null ? null :
+        (Vector) hints.get(DecodeHintType.POSSIBLE_FORMATS);
+    readers = new Vector();
     if (possibleFormats != null) {
       if (possibleFormats.contains(BarcodeFormat.EAN_13)) {
         readers.addElement(new EAN13Reader());
-      }
-      if (possibleFormats.contains(BarcodeFormat.UPC_A)) {
+      } else if (possibleFormats.contains(BarcodeFormat.UPC_A)) {
         readers.addElement(new UPCAReader());
       }
       if (possibleFormats.contains(BarcodeFormat.EAN_8)) {
@@ -52,41 +54,44 @@ public final class MultiFormatUPCEANReader extends AbstractOneDReader {
       }
     }
     if (readers.isEmpty()) {
-      readers.addElement(new EAN13Reader());      
-      readers.addElement(new UPCAReader());
+      readers.addElement(new EAN13Reader());
+      // UPC-A is covered by EAN-13
       readers.addElement(new EAN8Reader());
       readers.addElement(new UPCEReader());
     }
+  }
 
+  public Result decodeRow(int rowNumber, BitArray row, Hashtable hints) throws ReaderException {
     // Compute this location once and reuse it on multiple implementations
     int[] startGuardPattern = AbstractUPCEANReader.findStartGuardPattern(row);
-    for (int i = 0; i < readers.size(); i++) {
+    int size = readers.size();
+    for (int i = 0; i < size; i++) {
       UPCEANReader reader = (UPCEANReader) readers.elementAt(i);
       Result result;
       try {
-        result = reader.decodeRow(rowNumber, row, startGuardPattern);
+        result = reader.decodeRow(rowNumber, row, startGuardPattern, hints);
       } catch (ReaderException 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.
+      // Individually these are correct and their readers will both read such a code
+      // and correctly call it EAN-13, or UPC-A, respectively.
       //
-      // Here is, therefore, where we implement this logic:
+      // In this case, if we've been looking for both types, we'd like to call it
+      // a UPC-A code. But for efficiency we only run the EAN-13 decoder to also read
+      // UPC-A. So we special case it here, and convert an EAN-13 result to a UPC-A
+      // result if appropriate.
       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 new Result(result.getText().substring(1), null, result.getResultPoints(),
+            BarcodeFormat.UPC_A);
       }
       return result;
     }
 
-    throw new ReaderException("No barcode was detected in this image.");
+    throw ReaderException.getInstance();
   }
 
-}
\ No newline at end of file
+}