Major refactoring of 1D barcode code. Moved into com.google.zxing.oned package. Misc...

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

diff --git a/core/src/com/google/zxing/oned/UPCEReader.java b/core/src/com/google/zxing/oned/UPCEReader.java
new file mode 100644 (file)
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+++ b/core/src/com/google/zxing/oned/UPCEReader.java
@@ -0,0 +1,136 @@
+/*
+ * Copyright 2008 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.zxing.oned;
+
+import com.google.zxing.ReaderException;
+import com.google.zxing.common.BitArray;
+
+/**
+ * <p>Implements decoding of the UPC-E format.</p>
+ * <p/>
+ * <p><a href="http://www.barcodeisland.com/upce.phtml">This</a> is a great reference for
+ * UPC-E information.</p>
+ *
+ * @author srowen@google.com (Sean Owen)
+ */
+public final class UPCEReader extends AbstractUPCEANReader {
+
+  /**
+   * The pattern that marks the middle, and end, of a UPC-E pattern.
+   * There is no "second half" to a UPC-E barcode.
+   */
+  private static final int[] MIDDLE_END_PATTERN = {1, 1, 1, 1, 1, 1};
+
+  /**
+   * See {@link #L_AND_G_PATTERNS}; these values similarly represent patterns of
+   * even-odd parity encodings of digits that imply both the number system (0 or 1)
+   * used, and the check digit.
+   */
+  private static final int[][] NUMSYS_AND_CHECK_DIGIT_PATTERNS = {
+      {0x38, 0x34, 0x32, 0x31, 0x2C, 0x26, 0x23, 0x2A, 0x29, 0x25},
+      {0x07, 0x0B, 0x0D, 0x0E, 0x13, 0x19, 0x1C, 0x15, 0x16, 0x1A}
+  };
+
+  protected int decodeMiddle(BitArray row, int[] startRange, StringBuffer result) throws ReaderException {
+
+    int[] counters = new int[4];
+    int end = row.getSize();
+    int rowOffset = startRange[1];
+
+    int lgPatternFound = 0;
+
+    for (int x = 0; x < 6 && rowOffset < end; x++) {
+      int bestMatch = decodeDigit(row, counters, rowOffset, L_AND_G_PATTERNS);
+      result.append((char) ('0' + bestMatch % 10));
+      for (int i = 0; i < counters.length; i++) {
+        rowOffset += counters[i];
+      }
+      if (bestMatch >= 10) {
+        lgPatternFound |= 1 << (5 - x);
+      }
+    }
+
+    determineNumSysAndCheckDigit(result, lgPatternFound);
+
+    return rowOffset;
+  }
+
+  protected int[] decodeEnd(BitArray row, int endStart) throws ReaderException {
+    return findGuardPattern(row, endStart, true, MIDDLE_END_PATTERN);
+  }
+
+  protected boolean checkChecksum(String s) throws ReaderException {
+    return super.checkChecksum(convertUPCEtoUPCA(s));
+  }
+
+  private static void determineNumSysAndCheckDigit(StringBuffer resultString, int lgPatternFound)
+      throws ReaderException {
+
+    for (int numSys = 0; numSys <= 1; numSys++) {
+      for (int d = 0; d < 10; d++) {
+        if (lgPatternFound == NUMSYS_AND_CHECK_DIGIT_PATTERNS[numSys][d]) {
+          resultString.insert(0, (char) ('0' + numSys));
+          resultString.append((char) ('0' + d));
+          return;
+        }
+      }
+    }
+    throw new ReaderException("Unable to determine number system and check digit");
+  }
+
+  /**
+   * Expands a UPC-E value back into its full, equivalent UPC-A code value.
+   *
+   * @param upce UPC-E code as string of digits
+   * @return equivalent UPC-A code as string of digits
+   */
+  private static String convertUPCEtoUPCA(String upce) {
+    char[] upceChars = new char[6];
+    upce.getChars(1, 7, upceChars, 0);
+    StringBuffer result = new StringBuffer(12);
+    result.append(upce.charAt(0));
+    char lastChar = upceChars[5];
+    switch (lastChar) {
+      case '0':
+      case '1':
+      case '2':
+        result.append(upceChars, 0, 2);
+        result.append(lastChar);
+        result.append("0000");
+        result.append(upceChars, 2, 3);
+        break;
+      case '3':
+        result.append(upceChars, 0, 3);
+        result.append("00000");
+        result.append(upceChars, 3, 2);
+        break;
+      case '4':
+        result.append(upceChars, 0, 4);
+        result.append("00000");
+        result.append(upceChars[4]);
+        break;
+      default:
+        result.append(upceChars, 0, 5);
+        result.append("0000");
+        result.append(lastChar);
+        break;
+    }
+    result.append(upce.charAt(7));
+    return result.toString();
+  }
+
+}
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