package com.google.zxing.oned;
+import com.google.zxing.BarcodeFormat;
+import com.google.zxing.ChecksumException;
+import com.google.zxing.DecodeHintType;
+import com.google.zxing.FormatException;
+import com.google.zxing.NotFoundException;
import com.google.zxing.ReaderException;
import com.google.zxing.Result;
+import com.google.zxing.ResultMetadataType;
+import com.google.zxing.ResultPoint;
+import com.google.zxing.ResultPointCallback;
import com.google.zxing.common.BitArray;
+import java.util.Hashtable;
+
/**
- * <p>This interfaces captures addtional functionality that readers of
- * UPC/EAN family of barcodes should expose.</p>
+ * <p>Encapsulates functionality and implementation that is common to UPC and EAN families
+ * of one-dimensional barcodes.</p>
*
- * @author srowen@google.com (Sean Owen)
+ * @author dswitkin@google.com (Daniel Switkin)
+ * @author Sean Owen
+ * @author alasdair@google.com (Alasdair Mackintosh)
*/
-public interface UPCEANReader extends OneDReader {
+public abstract class UPCEANReader extends OneDReader {
+
+ // These two values are critical for determining how permissive the decoding will be.
+ // We've arrived at these values through a lot of trial and error. Setting them any higher
+ // lets false positives creep in quickly.
+ private static final int MAX_AVG_VARIANCE = (int) (PATTERN_MATCH_RESULT_SCALE_FACTOR * 0.42f);
+ private static final int MAX_INDIVIDUAL_VARIANCE = (int) (PATTERN_MATCH_RESULT_SCALE_FACTOR * 0.7f);
+
+ /**
+ * Start/end guard pattern.
+ */
+ static final int[] START_END_PATTERN = {1, 1, 1,};
+
+ /**
+ * Pattern marking the middle of a UPC/EAN pattern, separating the two halves.
+ */
+ static final int[] MIDDLE_PATTERN = {1, 1, 1, 1, 1};
+
+ /**
+ * "Odd", or "L" patterns used to encode UPC/EAN digits.
+ */
+ static final int[][] L_PATTERNS = {
+ {3, 2, 1, 1}, // 0
+ {2, 2, 2, 1}, // 1
+ {2, 1, 2, 2}, // 2
+ {1, 4, 1, 1}, // 3
+ {1, 1, 3, 2}, // 4
+ {1, 2, 3, 1}, // 5
+ {1, 1, 1, 4}, // 6
+ {1, 3, 1, 2}, // 7
+ {1, 2, 1, 3}, // 8
+ {3, 1, 1, 2} // 9
+ };
+
+ /**
+ * As above but also including the "even", or "G" patterns used to encode UPC/EAN digits.
+ */
+ static final int[][] L_AND_G_PATTERNS;
+
+ static {
+ L_AND_G_PATTERNS = new int[20][];
+ for (int i = 0; i < 10; i++) {
+ L_AND_G_PATTERNS[i] = L_PATTERNS[i];
+ }
+ for (int i = 10; i < 20; i++) {
+ int[] widths = L_PATTERNS[i - 10];
+ int[] reversedWidths = new int[widths.length];
+ for (int j = 0; j < widths.length; j++) {
+ reversedWidths[j] = widths[widths.length - j - 1];
+ }
+ L_AND_G_PATTERNS[i] = reversedWidths;
+ }
+ }
+
+ private final StringBuffer decodeRowStringBuffer;
+ private final UPCEANExtensionSupport extensionReader;
+ private final EANManufacturerOrgSupport eanManSupport;
+
+ protected UPCEANReader() {
+ decodeRowStringBuffer = new StringBuffer(20);
+ extensionReader = new UPCEANExtensionSupport();
+ eanManSupport = new EANManufacturerOrgSupport();
+ }
+
+ static int[] findStartGuardPattern(BitArray row) throws NotFoundException {
+ boolean foundStart = false;
+ int[] startRange = null;
+ int nextStart = 0;
+ while (!foundStart) {
+ startRange = findGuardPattern(row, nextStart, false, START_END_PATTERN);
+ int start = startRange[0];
+ nextStart = startRange[1];
+ // Make sure there is a quiet zone at least as big as the start pattern before the barcode.
+ // If this check would run off the left edge of the image, do not accept this barcode,
+ // as it is very likely to be a false positive.
+ int quietStart = start - (nextStart - start);
+ if (quietStart >= 0) {
+ foundStart = row.isRange(quietStart, start, false);
+ }
+ }
+ return startRange;
+ }
+
+ public Result decodeRow(int rowNumber, BitArray row, Hashtable hints)
+ throws NotFoundException, ChecksumException, FormatException {
+ return decodeRow(rowNumber, row, findStartGuardPattern(row), hints);
+ }
/**
* <p>Like {@link #decodeRow(int, BitArray, java.util.Hashtable)}, but
* allows caller to inform method about where the UPC/EAN start pattern is
* found. This allows this to be computed once and reused across many implementations.</p>
*/
- Result decodeRow(int rowNumber, BitArray row, int[] startGuardRange) throws ReaderException;
+ public Result decodeRow(int rowNumber, BitArray row, int[] startGuardRange, Hashtable hints)
+ throws NotFoundException, ChecksumException, FormatException {
+
+ ResultPointCallback resultPointCallback = hints == null ? null :
+ (ResultPointCallback) hints.get(DecodeHintType.NEED_RESULT_POINT_CALLBACK);
+
+ if (resultPointCallback != null) {
+ resultPointCallback.foundPossibleResultPoint(new ResultPoint(
+ (startGuardRange[0] + startGuardRange[1]) / 2.0f, rowNumber
+ ));
+ }
+
+ StringBuffer result = decodeRowStringBuffer;
+ result.setLength(0);
+ int endStart = decodeMiddle(row, startGuardRange, result);
+
+ if (resultPointCallback != null) {
+ resultPointCallback.foundPossibleResultPoint(new ResultPoint(
+ endStart, rowNumber
+ ));
+ }
+
+ int[] endRange = decodeEnd(row, endStart);
+
+ if (resultPointCallback != null) {
+ resultPointCallback.foundPossibleResultPoint(new ResultPoint(
+ (endRange[0] + endRange[1]) / 2.0f, rowNumber
+ ));
+ }
+
+
+ // Make sure there is a quiet zone at least as big as the end pattern after the barcode. The
+ // spec might want more whitespace, but in practice this is the maximum we can count on.
+ int end = endRange[1];
+ int quietEnd = end + (end - endRange[0]);
+ if (quietEnd >= row.getSize() || !row.isRange(end, quietEnd, false)) {
+ throw NotFoundException.getNotFoundInstance();
+ }
+
+ String resultString = result.toString();
+ if (!checkChecksum(resultString)) {
+ throw ChecksumException.getChecksumInstance();
+ }
+
+ float left = (float) (startGuardRange[1] + startGuardRange[0]) / 2.0f;
+ float right = (float) (endRange[1] + endRange[0]) / 2.0f;
+ BarcodeFormat format = getBarcodeFormat();
+ Result decodeResult = new Result(resultString,
+ null, // no natural byte representation for these barcodes
+ new ResultPoint[]{
+ new ResultPoint(left, (float) rowNumber),
+ new ResultPoint(right, (float) rowNumber)},
+ format);
+
+ try {
+ Result extensionResult = extensionReader.decodeRow(row, endRange[1]);
+ decodeResult.putAllMetadata(extensionResult.getResultMetadata());
+ } catch (ReaderException re) {
+ // continue
+ }
+
+ if (BarcodeFormat.EAN_13.equals(format) || BarcodeFormat.UPC_A.equals(format)) {
+ String countryID = eanManSupport.lookupCountryIdentifier(resultString);
+ if (countryID != null) {
+ decodeResult.putMetadata(ResultMetadataType.POSSIBLE_COUNTRY, countryID);
+ }
+ }
+
+ return decodeResult;
+ }
+
+ /**
+ * @return {@link #checkStandardUPCEANChecksum(String)}
+ */
+ boolean checkChecksum(String s) throws ChecksumException, FormatException {
+ return checkStandardUPCEANChecksum(s);
+ }
+
+ /**
+ * Computes the UPC/EAN checksum on a string of digits, and reports
+ * whether the checksum is correct or not.
+ *
+ * @param s string of digits to check
+ * @return true iff string of digits passes the UPC/EAN checksum algorithm
+ * @throws FormatException if the string does not contain only digits
+ */
+ private static boolean checkStandardUPCEANChecksum(String s) throws FormatException {
+ int length = s.length();
+ if (length == 0) {
+ return false;
+ }
+
+ int sum = 0;
+ for (int i = length - 2; i >= 0; i -= 2) {
+ int digit = (int) s.charAt(i) - (int) '0';
+ if (digit < 0 || digit > 9) {
+ throw FormatException.getFormatInstance();
+ }
+ sum += digit;
+ }
+ sum *= 3;
+ for (int i = length - 1; i >= 0; i -= 2) {
+ int digit = (int) s.charAt(i) - (int) '0';
+ if (digit < 0 || digit > 9) {
+ throw FormatException.getFormatInstance();
+ }
+ sum += digit;
+ }
+ return sum % 10 == 0;
+ }
+
+ int[] decodeEnd(BitArray row, int endStart) throws NotFoundException {
+ return findGuardPattern(row, endStart, false, START_END_PATTERN);
+ }
+
+ /**
+ * @param row row of black/white values to search
+ * @param rowOffset position to start search
+ * @param whiteFirst if true, indicates that the pattern specifies white/black/white/...
+ * pixel counts, otherwise, it is interpreted as black/white/black/...
+ * @param pattern pattern of counts of number of black and white pixels that are being
+ * searched for as a pattern
+ * @return start/end horizontal offset of guard pattern, as an array of two ints
+ * @throws NotFoundException if pattern is not found
+ */
+ static int[] findGuardPattern(BitArray row, int rowOffset, boolean whiteFirst, int[] pattern)
+ throws NotFoundException {
+ int patternLength = pattern.length;
+ int[] counters = new int[patternLength];
+ int width = row.getSize();
+ boolean isWhite = false;
+ while (rowOffset < width) {
+ isWhite = !row.get(rowOffset);
+ if (whiteFirst == isWhite) {
+ break;
+ }
+ rowOffset++;
+ }
+
+ int counterPosition = 0;
+ int patternStart = rowOffset;
+ for (int x = rowOffset; x < width; x++) {
+ boolean pixel = row.get(x);
+ if (pixel ^ isWhite) {
+ counters[counterPosition]++;
+ } else {
+ if (counterPosition == patternLength - 1) {
+ if (patternMatchVariance(counters, pattern, MAX_INDIVIDUAL_VARIANCE) < MAX_AVG_VARIANCE) {
+ return new int[]{patternStart, x};
+ }
+ patternStart += counters[0] + counters[1];
+ for (int y = 2; y < patternLength; y++) {
+ counters[y - 2] = counters[y];
+ }
+ counters[patternLength - 2] = 0;
+ counters[patternLength - 1] = 0;
+ counterPosition--;
+ } else {
+ counterPosition++;
+ }
+ counters[counterPosition] = 1;
+ isWhite = !isWhite;
+ }
+ }
+ throw NotFoundException.getNotFoundInstance();
+ }
+
+ /**
+ * Attempts to decode a single UPC/EAN-encoded digit.
+ *
+ * @param row row of black/white values to decode
+ * @param counters the counts of runs of observed black/white/black/... values
+ * @param rowOffset horizontal offset to start decoding from
+ * @param patterns the set of patterns to use to decode -- sometimes different encodings
+ * for the digits 0-9 are used, and this indicates the encodings for 0 to 9 that should
+ * be used
+ * @return horizontal offset of first pixel beyond the decoded digit
+ * @throws NotFoundException if digit cannot be decoded
+ */
+ static int decodeDigit(BitArray row, int[] counters, int rowOffset, int[][] patterns)
+ throws NotFoundException {
+ recordPattern(row, rowOffset, counters);
+ int bestVariance = MAX_AVG_VARIANCE; // worst variance we'll accept
+ int bestMatch = -1;
+ int max = patterns.length;
+ for (int i = 0; i < max; i++) {
+ int[] pattern = patterns[i];
+ int variance = patternMatchVariance(counters, pattern, MAX_INDIVIDUAL_VARIANCE);
+ if (variance < bestVariance) {
+ bestVariance = variance;
+ bestMatch = i;
+ }
+ }
+ if (bestMatch >= 0) {
+ return bestMatch;
+ } else {
+ throw NotFoundException.getNotFoundInstance();
+ }
+ }
+
+ /**
+ * Get the format of this decoder.
+ *
+ * @return The 1D format.
+ */
+ abstract BarcodeFormat getBarcodeFormat();
+
+ /**
+ * Subclasses override this to decode the portion of a barcode between the start
+ * and end guard patterns.
+ *
+ * @param row row of black/white values to search
+ * @param startRange start/end offset of start guard pattern
+ * @param resultString {@link StringBuffer} to append decoded chars to
+ * @return horizontal offset of first pixel after the "middle" that was decoded
+ * @throws NotFoundException if decoding could not complete successfully
+ */
+ protected abstract int decodeMiddle(BitArray row, int[] startRange, StringBuffer resultString)
+ throws NotFoundException;
-}
\ No newline at end of file
+}
projects / zxing.git / blobdiff