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341 lines
11 KiB
C++
341 lines
11 KiB
C++
// -*- mode:c++; tab-width:2; indent-tabs-mode:nil; c-basic-offset:2 -*-
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/*
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* Copyright 2010 ZXing authors All rights reserved.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <zxing/ZXing.h>
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#include <zxing/oned/CodaBarReader.h>
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#include <zxing/oned/OneDResultPoint.h>
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#include <zxing/common/Array.h>
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#include <zxing/ReaderException.h>
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#include <zxing/NotFoundException.h>
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#include <zxing/FormatException.h>
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#include <zxing/ChecksumException.h>
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#include <math.h>
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#include <sstream>
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using std::vector;
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using std::string;
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using zxing::NotFoundException;
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using zxing::FormatException;
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using zxing::ChecksumException;
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using zxing::Ref;
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using zxing::Result;
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using zxing::oned::CodaBarReader;
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// VC++
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using zxing::BitArray;
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namespace {
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char const ALPHABET_STRING[] = "0123456789-$:/.+ABCD";
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char const* const ALPHABET = ALPHABET_STRING;
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/**
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* These represent the encodings of characters, as patterns of wide and narrow bars. The 7 least-significant bits of
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* each int correspond to the pattern of wide and narrow, with 1s representing "wide" and 0s representing narrow.
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*/
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const int CHARACTER_ENCODINGS[] = {
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0x003, 0x006, 0x009, 0x060, 0x012, 0x042, 0x021, 0x024, 0x030, 0x048, // 0-9
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0x00c, 0x018, 0x045, 0x051, 0x054, 0x015, 0x01A, 0x029, 0x00B, 0x00E, // -$:/.+ABCD
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};
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// minimal number of characters that should be present (inclusing start and stop characters)
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// under normal circumstances this should be set to 3, but can be set higher
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// as a last-ditch attempt to reduce false positives.
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const int MIN_CHARACTER_LENGTH = 3;
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// official start and end patterns
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const char STARTEND_ENCODING[] = {'A', 'B', 'C', 'D', 0};
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// some codabar generator allow the codabar string to be closed by every
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// character. This will cause lots of false positives!
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// some industries use a checksum standard but this is not part of the original codabar standard
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// for more information see : http://www.mecsw.com/specs/codabar.html
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}
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// These values are critical for determining how permissive the decoding
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// will be. All stripe sizes must be within the window these define, as
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// compared to the average stripe size.
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const int CodaBarReader::MAX_ACCEPTABLE =
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(int) (PATTERN_MATCH_RESULT_SCALE_FACTOR * 2.0f);
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const int CodaBarReader::PADDING =
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(int) (PATTERN_MATCH_RESULT_SCALE_FACTOR * 1.5f);
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CodaBarReader::CodaBarReader()
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: counters(80, 0), counterLength(0) {}
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Ref<Result> CodaBarReader::decodeRow(int rowNumber, Ref<BitArray> row) {
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{ // Arrays.fill(counters, 0);
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int size = counters.size();
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counters.resize(0);
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counters.resize(size); }
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setCounters(row);
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int startOffset = findStartPattern();
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int nextStart = startOffset;
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decodeRowResult.clear();
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do {
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int charOffset = toNarrowWidePattern(nextStart);
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if (charOffset == -1) {
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throw NotFoundException();
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}
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// Hack: We store the position in the alphabet table into a
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// StringBuilder, so that we can access the decoded patterns in
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// validatePattern. We'll translate to the actual characters later.
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decodeRowResult.append(1, (char)charOffset);
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nextStart += 8;
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// Stop as soon as we see the end character.
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if (decodeRowResult.length() > 1 &&
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arrayContains(STARTEND_ENCODING, ALPHABET[charOffset])) {
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break;
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}
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} while (nextStart < counterLength); // no fixed end pattern so keep on reading while data is available
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// Look for whitespace after pattern:
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int trailingWhitespace = counters[nextStart - 1];
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int lastPatternSize = 0;
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for (int i = -8; i < -1; i++) {
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lastPatternSize += counters[nextStart + i];
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}
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// We need to see whitespace equal to 50% of the last pattern size,
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// otherwise this is probably a false positive. The exception is if we are
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// at the end of the row. (I.e. the barcode barely fits.)
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if (nextStart < counterLength && trailingWhitespace < lastPatternSize / 2) {
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throw NotFoundException();
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}
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validatePattern(startOffset);
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// Translate character table offsets to actual characters.
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for (int i = 0; i < (int)decodeRowResult.length(); i++) {
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decodeRowResult[i] = ALPHABET[(int)decodeRowResult[i]];
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}
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// Ensure a valid start and end character
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char startchar = decodeRowResult[0];
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if (!arrayContains(STARTEND_ENCODING, startchar)) {
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throw NotFoundException();
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}
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char endchar = decodeRowResult[decodeRowResult.length() - 1];
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if (!arrayContains(STARTEND_ENCODING, endchar)) {
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throw NotFoundException();
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}
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// remove stop/start characters character and check if a long enough string is contained
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if ((int)decodeRowResult.length() <= MIN_CHARACTER_LENGTH) {
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// Almost surely a false positive ( start + stop + at least 1 character)
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throw NotFoundException();
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}
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decodeRowResult.erase(decodeRowResult.length() - 1, 1);
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decodeRowResult.erase(0, 1);
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int runningCount = 0;
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for (int i = 0; i < startOffset; i++) {
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runningCount += counters[i];
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}
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float left = (float) runningCount;
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for (int i = startOffset; i < nextStart - 1; i++) {
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runningCount += counters[i];
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}
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float right = (float) runningCount;
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ArrayRef< Ref<ResultPoint> > resultPoints(2);
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resultPoints[0] =
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Ref<OneDResultPoint>(new OneDResultPoint(left, (float) rowNumber));
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resultPoints[1] =
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Ref<OneDResultPoint>(new OneDResultPoint(right, (float) rowNumber));
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return Ref<Result>(new Result(Ref<String>(new String(decodeRowResult)),
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ArrayRef<char>(),
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resultPoints,
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BarcodeFormat::CODABAR));
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}
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void CodaBarReader::validatePattern(int start) {
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// First, sum up the total size of our four categories of stripe sizes;
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vector<int> sizes (4, 0);
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vector<int> counts (4, 0);
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int end = decodeRowResult.length() - 1;
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// We break out of this loop in the middle, in order to handle
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// inter-character spaces properly.
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int pos = start;
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for (int i = 0; true; i++) {
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int pattern = CHARACTER_ENCODINGS[(int)decodeRowResult[i]];
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for (int j = 6; j >= 0; j--) {
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// Even j = bars, while odd j = spaces. Categories 2 and 3 are for
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// long stripes, while 0 and 1 are for short stripes.
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int category = (j & 1) + (pattern & 1) * 2;
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sizes[category] += counters[pos + j];
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counts[category]++;
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pattern >>= 1;
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}
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if (i >= end) {
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break;
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}
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// We ignore the inter-character space - it could be of any size.
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pos += 8;
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}
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// Calculate our allowable size thresholds using fixed-point math.
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vector<int> maxes (4, 0);
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vector<int> mins (4, 0);
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// Define the threshold of acceptability to be the midpoint between the
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// average small stripe and the average large stripe. No stripe lengths
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// should be on the "wrong" side of that line.
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for (int i = 0; i < 2; i++) {
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mins[i] = 0; // Accept arbitrarily small "short" stripes.
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mins[i + 2] = ((sizes[i] << INTEGER_MATH_SHIFT) / counts[i] +
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(sizes[i + 2] << INTEGER_MATH_SHIFT) / counts[i + 2]) >> 1;
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maxes[i] = mins[i + 2];
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maxes[i + 2] = (sizes[i + 2] * MAX_ACCEPTABLE + PADDING) / counts[i + 2];
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}
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// Now verify that all of the stripes are within the thresholds.
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pos = start;
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for (int i = 0; true; i++) {
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int pattern = CHARACTER_ENCODINGS[(int)decodeRowResult[i]];
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for (int j = 6; j >= 0; j--) {
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// Even j = bars, while odd j = spaces. Categories 2 and 3 are for
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// long stripes, while 0 and 1 are for short stripes.
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int category = (j & 1) + (pattern & 1) * 2;
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int size = counters[pos + j] << INTEGER_MATH_SHIFT;
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if (size < mins[category] || size > maxes[category]) {
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throw NotFoundException();
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}
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pattern >>= 1;
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}
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if (i >= end) {
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break;
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}
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pos += 8;
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}
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}
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/**
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* Records the size of all runs of white and black pixels, starting with white.
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* This is just like recordPattern, except it records all the counters, and
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* uses our builtin "counters" member for storage.
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* @param row row to count from
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*/
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void CodaBarReader::setCounters(Ref<BitArray> row) {
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counterLength = 0;
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// Start from the first white bit.
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int i = row->getNextUnset(0);
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int end = row->getSize();
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if (i >= end) {
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throw NotFoundException();
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}
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bool isWhite = true;
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int count = 0;
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for (; i < end; i++) {
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if (row->get(i) ^ isWhite) { // that is, exactly one is true
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count++;
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} else {
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counterAppend(count);
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count = 1;
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isWhite = !isWhite;
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}
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}
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counterAppend(count);
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}
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void CodaBarReader::counterAppend(int e) {
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if (counterLength < (int)counters.size()) {
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counters[counterLength] = e;
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} else {
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counters.push_back(e);
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}
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counterLength++;
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}
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int CodaBarReader::findStartPattern() {
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for (int i = 1; i < counterLength; i += 2) {
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int charOffset = toNarrowWidePattern(i);
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if (charOffset != -1 && arrayContains(STARTEND_ENCODING, ALPHABET[charOffset])) {
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// Look for whitespace before start pattern, >= 50% of width of start pattern
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// We make an exception if the whitespace is the first element.
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int patternSize = 0;
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for (int j = i; j < i + 7; j++) {
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patternSize += counters[j];
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}
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if (i == 1 || counters[i-1] >= patternSize / 2) {
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return i;
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}
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}
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}
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throw NotFoundException();
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}
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bool CodaBarReader::arrayContains(char const array[], char key) {
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return strchr(array, key) != 0;
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}
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int CodaBarReader::toNarrowWidePattern(int position) {
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int end = position + 7;
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if (end >= counterLength) {
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return -1;
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}
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vector<int>& theCounters = counters;
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int maxBar = 0;
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int minBar = std::numeric_limits<int>::max();
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for (int j = position; j < end; j += 2) {
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int currentCounter = theCounters[j];
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if (currentCounter < minBar) {
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minBar = currentCounter;
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}
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if (currentCounter > maxBar) {
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maxBar = currentCounter;
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}
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}
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int thresholdBar = (minBar + maxBar) / 2;
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int maxSpace = 0;
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int minSpace = std::numeric_limits<int>::max();
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for (int j = position + 1; j < end; j += 2) {
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int currentCounter = theCounters[j];
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if (currentCounter < minSpace) {
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minSpace = currentCounter;
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}
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if (currentCounter > maxSpace) {
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maxSpace = currentCounter;
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}
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}
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int thresholdSpace = (minSpace + maxSpace) / 2;
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int bitmask = 1 << 7;
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int pattern = 0;
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for (int i = 0; i < 7; i++) {
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int threshold = (i & 1) == 0 ? thresholdBar : thresholdSpace;
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bitmask >>= 1;
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if (theCounters[position + i] > threshold) {
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pattern |= bitmask;
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}
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}
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for (int i = 0; i < ZXING_ARRAY_LEN(CHARACTER_ENCODINGS); i++) {
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if (CHARACTER_ENCODINGS[i] == pattern) {
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return i;
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}
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}
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return -1;
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}
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