Added the initial version of my UPC reader and modified some common files

as necessary to get it building and used by the J2SE command line test.


git-svn-id: https://zxing.googlecode.com/svn/trunk@31 59b500cc-1b3d-0410-9834-0bbf25fbcc57

core/src/com/google/zxing/MultiFormatReader.java

@@ -17,6 +17,7 @@
 package com.google.zxing;
 
 import com.google.zxing.qrcode.QRCodeReader;
+import com.google.zxing.upc.UPCReader;
 
 import java.util.Hashtable;
 
@@ -39,13 +40,37 @@ public final class MultiFormatReader implements Reader {
       throws ReaderException {
     Hashtable possibleFormats =
         hints == null ? null : (Hashtable) hints.get(DecodeHintType.POSSIBLE_FORMATS);
-    // TODO for now we are only support QR Code so this behaves accordingly. This needs to
-    // become more sophisticated
-    if (possibleFormats == null || possibleFormats.contains(BarcodeFormat.QR_CODE)) {
-      return new QRCodeReader().decode(image, hints);
+    boolean tryUPC = false;
+    boolean tryQR = false;
+    
+    if (possibleFormats == null) {
+      tryUPC = true;
+      tryQR = true;
+    } else if (possibleFormats.contains(BarcodeFormat.UPC)) {
+      tryUPC = true;
+    } else if (possibleFormats.contains(BarcodeFormat.QR_CODE)) {
+      tryQR = true;
     } else {
       throw new ReaderException();
     }
+    
+    // UPC is much faster to decode, so try it first.
+    if (tryUPC) {
+      try {
+        return new UPCReader().decode(image, hints);
+      } catch (ReaderException e) {
+      }
+    }
+    
+    // Then fall through to QR codes.
+    if (tryQR) {
+      try {
+        return new QRCodeReader().decode(image, hints);
+      } catch (ReaderException e) {
+      }
+    }
+    
+    throw new ReaderException();
   }
 
 }

core/src/com/google/zxing/common/BitArray.java

@@ -23,14 +23,12 @@ package com.google.zxing.common;
  */
 public final class BitArray {
 
-  private final int[] bits;
+  private int[] bits;
+  private int size;
 
   public BitArray(int size) {
-    int arraySize = size >> 5;
-    if ((size & 0x1F) != 0) {
-      arraySize++;
-    }
-    bits = new int[arraySize];
+    this.size = size;
+    this.bits = makeArray(size);
   }
 
   /**
@@ -55,7 +53,7 @@ public final class BitArray {
    *
    * @param i first bit to set
    * @param newBits the new value of the next 32 bits. Note again that the least-significant bit
-   *  correponds to bit i, the next-least-significant to i+1, and so on.
+   *  corresponds to bit i, the next-least-significant to i+1, and so on.
    */
   public void setBulk(int i, int newBits) {
     bits[i >> 5] = newBits;
@@ -78,5 +76,31 @@ public final class BitArray {
   public int[] getBitArray() {
     return bits;
   }
+  
+  /**
+   * Reverses all bits in the array.
+   */
+  public void reverse() {
+    int[] newBits = makeArray(size);
+    int max = newBits.length;
+    for (int i = 0; i < max; i++) {
+      newBits[i] = 0;
+    }
+    for (int i = 0; i < size; i++) {
+      if (this.get(size - i - 1)) {
+        newBits[i >> 5] |= 1 << (i & 0x1F);
+      }
+    }
+    bits = newBits;
+  }
+  
+  private int[] makeArray(int size) {
+    int arraySize = size >> 5;
+    if ((size & 0x1F) != 0) {
+      arraySize++;
+    }
+    int[] result = new int[arraySize];
+    return result;
+  }
 
 }

core/src/com/google/zxing/upc/UPCDecoder.java

@@ -0,0 +1,260 @@
+/*
+ * Copyright 2007 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.upc;
+
+import com.google.zxing.common.BitArray;
+import com.google.zxing.MonochromeBitmapSource;
+
+import java.util.Arrays;
+
+/**
+ * This class takes a bitmap, and attempts to return a String which is the contents of the UPC
+ * barcode in the image. It should be scale-invariant, but does not make any corrections for
+ * rotation or skew.
+ *
+ * @author dswitkin@google.com (Daniel Switkin)
+ */
+public class UPCDecoder {
+  UPCDecoder(MonochromeBitmapSource bitmap) {
+	mBitmap = bitmap;
+    if (bitmap != null) {
+      mWidth = bitmap.getWidth();
+      mHeight = bitmap.getHeight();
+    }
+  }
+
+  // To decode the image, we follow a search pattern defined in kBitmapSearchPattern. It is a
+  // list of percentages which translate to row numbers to scan across. For each row, we scan
+  // left to right, and if that fails, we reverse the row in place and try again to see if the
+  // bar code was upside down.
+  public String decode() {
+    if (mBitmap == null) return "";
+
+    BitArray rowData = new BitArray(mWidth);
+    String longestResult = "";
+    int found = -1;
+    for (int x = 0; x < kBitmapSearchPattern.length; x++) {
+      int row = mHeight * kBitmapSearchPattern[x] / 100;
+      mBitmap.getBlackRow(row, rowData, 0, mWidth);
+
+      if (decodeRow(rowData)) {
+        found = x;
+        break;
+      }
+      //Log("decode: row " + row + " normal result: " + mResult);
+      if (mResult.length() > longestResult.length()) {
+        longestResult = mResult;
+      }
+      
+      rowData.reverse();
+      if (decodeRow(rowData)) {
+        found = x;
+        break;
+      }
+      //Log("decode: row " + row + " inverted result: " + mResult);
+      if (mResult.length() > longestResult.length()) {
+        longestResult = mResult;
+      }
+    }
+    
+    if (found >= 0) return mResult;
+    else return "";
+  }
+  
+  // UPC-A bar codes are made up of a left marker, six digits, a middle marker, six more digits,
+  // and an end marker, reading from left to right. For more information, see:
+  //
+  // http://en.wikipedia.org/wiki/Universal_Product_Code
+  //
+  // TODO: Add support for UPC-E Zero Compressed bar codes.
+  // TODO: Add support for EAN-13 (European Article Number) bar codes.
+  // FIXME: Don't trust the first result from findPattern() for the start sequence - resume from
+  // that spot and try to start again if finding digits fails.
+  private boolean decodeRow(BitArray rowData) {
+    mResult = "";
+    int rowOffset = findPattern(rowData, 0, kStartEndPattern, false);
+    if (rowOffset < 0) return false;
+    //Log("Start pattern ends at column " + rowOffset);
+
+    rowOffset = decodeOneSide(rowData, rowOffset);
+    if (rowOffset < 0) return false;
+
+    rowOffset = findPattern(rowData, rowOffset, kMiddlePattern, true);
+    if (rowOffset < 0) return false;
+    //Log("Middle pattern ends at column " + rowOffset);
+
+    rowOffset = decodeOneSide(rowData, rowOffset);
+    if (rowOffset < 0) return false;
+
+    // We could attempt to read the end pattern for sanity, but there's not much point.
+    // UPC-A codes have 12 digits, so any other result is garbage.
+    return (mResult.length() == 12);
+  }
+
+  private int decodeOneSide(BitArray rowData, int rowOffset) {
+    int[] counters = new int[4];
+    for (int x = 0; x < 6 && rowOffset < mWidth; x++) {
+      recordPattern(rowData, rowOffset, counters, 4);
+      for (int y = 0; y < 4; y++) {
+        rowOffset += counters[y];
+      }
+      char c = findDigit(counters);
+      if (c == '-') {
+        return -1;
+      } else {
+        mResult += c;
+      }
+    }
+    return rowOffset;
+  }
+
+  // Returns the horizontal position just after the pattern was found if successful, otherwise
+  // returns -1 if the pattern was not found. Searches are always left to right, and patterns
+  // begin on white or black based on the flag.
+  private int findPattern(BitArray rowData, int rowOffset, byte[] pattern, boolean whiteFirst) {
+    int[] counters = new int[pattern.length];
+    int width = mWidth;
+    boolean isWhite = false;
+    for (; rowOffset < width; rowOffset++) {
+      isWhite = !rowData.get(rowOffset);
+      if (whiteFirst == isWhite) {
+        break;
+      }
+    }
+
+    int counterPosition = 0;
+    for (int x = rowOffset; x < width; x++) {
+      boolean pixel = rowData.get(x);
+      if ((!pixel && isWhite) || (pixel && !isWhite)) {
+        counters[counterPosition]++;
+      } else {
+        if (counterPosition == pattern.length - 1) {
+          if (doesPatternMatch(counters, pattern)) {
+            return x;
+          }
+          for (int y = 2; y < pattern.length; y++) {
+            counters[y - 2] = counters[y];
+          }
+          counterPosition--;
+        } else {
+          counterPosition++;
+        }
+        counters[counterPosition] = 1;
+        isWhite = !isWhite;
+      }
+    }
+    return -1;
+  }
+
+  // Records a pattern of alternating white and black pixels, returning an array of how many
+  // pixels of each color were seen. The pattern begins immediately based on the color of the
+  // first pixel encountered, so a patternSize of 3 could result in WBW or BWB.
+  private void recordPattern(BitArray rowData, int rowOffset, int[] counters, int patternSize) {
+    Arrays.fill(counters, 0);
+    boolean isWhite = !rowData.get(rowOffset);
+
+    int counterPosition = 0;
+    int width = mWidth;
+    for (int x = rowOffset; x < width; x++) {
+      boolean pixel = rowData.get(x);
+      if ((!pixel && isWhite) || (pixel && !isWhite)) {
+        counters[counterPosition]++;
+      } else {
+        counterPosition++;
+        if (counterPosition == patternSize) {
+          return;
+        } else {
+          counters[counterPosition] = 1;
+          isWhite = !isWhite;
+        }
+      }
+    }
+  }
+
+  // This is an optimized version of doesPatternMatch() which is specific to recognizing digits.
+  // The average is divided by 7 because there are 7 bits per digit, even though the color only
+  // alternates four times. kDigitPatterns has been premultiplied by 10 for efficiency. Notice
+  // that the contents of the counters array are modified to save an extra allocation, so don't
+  // use these values after returning from this call.
+  // TODO: add EAN even parity support
+  private char findDigit(int[] counters) {
+    int total = counters[0] + counters[1] + counters[2] + counters[3];
+    int average = total * 10 / 7;
+    for (int x = 0; x < 4; x++) {
+      counters[x] = counters[x] * 100 / average;
+    }
+
+    for (int x = 0; x < 10; x++) {
+      boolean match = true;
+      for (int y = 0; y < 4; y++) {
+        int diff = counters[y] - kDigitPatterns[x][y];
+        if (diff > kTolerance || diff < -kTolerance) {
+          match = false;
+          break;
+        }
+      }
+      if (match) return kDigits[x];
+    }
+    return '-';
+  }
+
+  // Finds whether the given set of pixel counters matches the requested pattern. Taking an
+  // average based on the number of counters offers some robustness when antialiased edges get
+  // interpreted as the wrong color.
+  // TODO: Remove the divide for performance.
+  private boolean doesPatternMatch(int[] counters, byte[] pattern) {
+    int total = 0;
+    for (int x = 0; x < counters.length; x++) {
+      total += counters[x];
+    }
+    int average = total * 10 / counters.length;
+
+    for (int x = 0; x < counters.length; x++) {
+      int scaledCounter = counters[x] * 100 / average;
+      int scaledPattern = pattern[x] * 10;
+      if (scaledCounter < scaledPattern - kTolerance || scaledCounter > scaledPattern + kTolerance) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  private static final byte[] kBitmapSearchPattern = { 50, 49, 51, 48, 52, 46, 54, 43, 57, 40, 60 };
+  private static final byte[] kStartEndPattern = { 1, 1, 1 };
+  private static final byte[] kMiddlePattern = { 1, 1, 1, 1, 1 };
+
+  private static final byte[][] kDigitPatterns = {
+    { 30, 20, 10, 10 }, // 0
+    { 20, 20, 20, 10 }, // 1
+    { 20, 10, 20, 20 }, // 2
+    { 10, 40, 10, 10 }, // 3
+    { 10, 10, 30, 20 }, // 4
+    { 10, 20, 30, 10 }, // 5
+    { 10, 10, 10, 40 }, // 6
+    { 10, 30, 10, 20 }, // 7
+    { 10, 20, 10, 30 }, // 8
+    { 30, 10, 10, 20 }  // 9
+  };
+
+  private static final char[] kDigits = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' };
+  private static final int kTolerance = 5;
+
+  private MonochromeBitmapSource mBitmap;
+  private int mWidth;
+  private int mHeight;
+  private String mResult;
+}

core/src/com/google/zxing/upc/UPCReader.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2007 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.upc;
+
+import com.google.zxing.MonochromeBitmapSource;
+import com.google.zxing.Reader;
+import com.google.zxing.ReaderException;
+import com.google.zxing.Result;
+import com.google.zxing.ResultPoint;
+
+import java.util.Hashtable;
+
+/**
+ * A reader which decodes UPC-A barcodes.
+ *
+ * @author dswitkin@google.com (Daniel Switkin)
+ */
+public final class UPCReader implements Reader {
+
+  private static final ResultPoint[] NO_POINTS = new ResultPoint[0];
+
+  /**
+   * Locates and decodes a UPC barcode in an image.
+   *
+   * @return a String representing the digits found
+   * @throws ReaderException if a barcode cannot be found or decoded
+   */
+  public Result decode(MonochromeBitmapSource image) throws ReaderException {
+    return decode(image, null);
+  }
+
+  public Result decode(MonochromeBitmapSource image, Hashtable hints)
+      throws ReaderException {
+    UPCDecoder decoder = new UPCDecoder(image);
+    String result = decoder.decode();
+    if (result == null || result.length() == 0) {
+      throw new ReaderException("No UPC barcode found");
+    }
+    return new Result(result, NO_POINTS);
+  }
+}

javase/src/com/google/zxing/client/j2se/CommandLineRunner.java

@@ -53,9 +53,17 @@ public final class CommandLineRunner {
 
   private static void decode(URI uri) throws IOException, ReaderException {
     BufferedImage image = ImageIO.read(uri.toURL());
-    String result =
-        new MultiFormatReader().decode(new BufferedImageMonochromeBitmapSource(image)).getText();
-    System.out.println(result);
+    if (image == null) {
+      System.out.println(uri.toString() + ": Could not load image");
+      return;
+    }
+    try {
+      String result =
+          new MultiFormatReader().decode(new BufferedImageMonochromeBitmapSource(image)).getText();
+      System.out.println(uri.toString() + ": " + result);
+    } catch (ReaderException e) {
+      System.out.println(uri.toString() + ": No barcode found");
+    }
   }
 
 }