X-Git-Url: http://git.rot13.org/?a=blobdiff_plain;f=core%2Fsrc%2Fcom%2Fgoogle%2Fzxing%2Foned%2FAbstractUPCEANReader.java;h=5336e0dc306afcec333cea5fab00967367f5f565;hb=a96a22b731c6402277a70ca54ccec32088adbfbb;hp=26262fd5bfe16165066aa7ec886e844b25b02810;hpb=61db77fd4960c475243bfb49cc3b6877aef5d8de;p=zxing.git diff --git a/core/src/com/google/zxing/oned/AbstractUPCEANReader.java b/core/src/com/google/zxing/oned/AbstractUPCEANReader.java index 26262fd5..5336e0dc 100644 --- a/core/src/com/google/zxing/oned/AbstractUPCEANReader.java +++ b/core/src/com/google/zxing/oned/AbstractUPCEANReader.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. @@ -30,12 +30,13 @@ import java.util.Hashtable; * of one-dimensional barcodes.

* * @author dswitkin@google.com (Daniel Switkin) - * @author srowen@google.com (Sean Owen) + * @author Sean Owen * @author alasdair@google.com (Alasdair Mackintosh) */ public abstract class AbstractUPCEANReader extends AbstractOneDReader implements UPCEANReader { - private static final float MAX_VARIANCE = 0.4f; + 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. @@ -83,7 +84,13 @@ public abstract class AbstractUPCEANReader extends AbstractOneDReader implements } } - static int[] findStartGuardPattern(final BitArray row) throws ReaderException { + private final StringBuffer decodeRowStringBuffer; + + protected AbstractUPCEANReader() { + decodeRowStringBuffer = new StringBuffer(20); + } + + static int[] findStartGuardPattern(BitArray row) throws ReaderException { boolean foundStart = false; int[] startRange = null; int nextStart = 0; @@ -91,9 +98,13 @@ public abstract class AbstractUPCEANReader extends AbstractOneDReader implements startRange = findGuardPattern(row, nextStart, false, START_END_PATTERN); int start = startRange[0]; nextStart = startRange[1]; - // As a check, we want to see some white in front of this "start pattern", - // maybe as wide as the start pattern itself? - foundStart = row.isRange(Math.max(0, start - 2 * (startRange[1] - start)), start, false); + // 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; } @@ -103,34 +114,43 @@ public abstract class AbstractUPCEANReader extends AbstractOneDReader implements } public final Result decodeRow(int rowNumber, BitArray row, int[] startGuardRange) throws ReaderException { - - StringBuffer result = new StringBuffer(); - + StringBuffer result = decodeRowStringBuffer; + result.setLength(0); int endStart = decodeMiddle(row, startGuardRange, result); - int[] endRange = decodeEnd(row, endStart); - // Check for whitespace after the pattern + // 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]; - if (!row.isRange(end, Math.min(row.getSize(), end + 2 * (end - endRange[0])), false)) { - throw new ReaderException("Pattern not followed by whitespace"); + int quietEnd = end + (end - endRange[0]); + if (quietEnd >= row.getSize() || !row.isRange(end, quietEnd, false)) { + throw ReaderException.getInstance(); } String resultString = result.toString(); if (!checkChecksum(resultString)) { - throw new ReaderException("Checksum failed"); + throw ReaderException.getInstance(); } - return new Result( - resultString, + float left = (float) (startGuardRange[1] + startGuardRange[0]) / 2.0f; + float right = (float) (endRange[1] + endRange[0]) / 2.0f; + return new Result(resultString, + null, // no natural byte representation for these barcodes new ResultPoint[]{ - new GenericResultPoint((float) (startGuardRange[1] - startGuardRange[0]) / 2.0f, (float) rowNumber), - new GenericResultPoint((float) (endRange[1] - endRange[0]) / 2.0f, (float) rowNumber)}, + new GenericResultPoint(left, (float) rowNumber), + new GenericResultPoint(right, (float) rowNumber)}, getBarcodeFormat()); } abstract BarcodeFormat getBarcodeFormat(); + /** + * @return {@link #checkStandardUPCEANChecksum(String)} + */ + boolean checkChecksum(String s) throws ReaderException { + return checkStandardUPCEANChecksum(s); + } + /** * Computes the UPC/EAN checksum on a string of digits, and reports * whether the checksum is correct or not. @@ -139,13 +159,17 @@ public abstract class AbstractUPCEANReader extends AbstractOneDReader implements * @return true iff string of digits passes the UPC/EAN checksum algorithm * @throws ReaderException if the string does not contain only digits */ - boolean checkChecksum(String s) throws ReaderException { - int sum = 0; + public static boolean checkStandardUPCEANChecksum(String s) throws ReaderException { 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 new ReaderException("Illegal character during checksum"); + throw ReaderException.getInstance(); } sum += digit; } @@ -153,7 +177,7 @@ public abstract class AbstractUPCEANReader extends AbstractOneDReader implements for (int i = length - 1; i >= 0; i -= 2) { int digit = (int) s.charAt(i) - (int) '0'; if (digit < 0 || digit > 9) { - throw new ReaderException("Illegal character during checksum"); + throw ReaderException.getInstance(); } sum += digit; } @@ -208,7 +232,7 @@ public abstract class AbstractUPCEANReader extends AbstractOneDReader implements counters[counterPosition]++; } else { if (counterPosition == patternLength - 1) { - if (patternMatchVariance(counters, pattern) < MAX_VARIANCE) { + if (patternMatchVariance(counters, pattern, MAX_INDIVIDUAL_VARIANCE) < MAX_AVG_VARIANCE) { return new int[]{patternStart, x}; } patternStart += counters[0] + counters[1]; @@ -225,7 +249,7 @@ public abstract class AbstractUPCEANReader extends AbstractOneDReader implements isWhite = !isWhite; } } - throw new ReaderException("Can't find pattern"); + throw ReaderException.getInstance(); } /** @@ -240,25 +264,24 @@ public abstract class AbstractUPCEANReader extends AbstractOneDReader implements * @return horizontal offset of first pixel beyond the decoded digit * @throws ReaderException if digit cannot be decoded */ - static int decodeDigit(BitArray row, - int[] counters, - int rowOffset, - int[][] patterns) throws ReaderException { + static int decodeDigit(BitArray row, int[] counters, int rowOffset, int[][] patterns) + throws ReaderException { recordPattern(row, rowOffset, counters); - float bestVariance = MAX_VARIANCE; // worst variance we'll accept + int bestVariance = MAX_AVG_VARIANCE; // worst variance we'll accept int bestMatch = -1; - for (int d = 0; d < patterns.length; d++) { - int[] pattern = patterns[d]; - float variance = patternMatchVariance(counters, pattern); + 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 = d; + bestMatch = i; } } if (bestMatch >= 0) { return bestMatch; } else { - throw new ReaderException("Could not match any digit in pattern"); + throw ReaderException.getInstance(); } }