1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
/*
* Copyright 2020 Axel Waggershauser
*/
// SPDX-License-Identifier: Apache-2.0
#include "ODDataBarCommon.h"
#include <cmath>
namespace ZXing::OneD::DataBar {
static int combins(int n, int r)
{
int maxDenom;
int minDenom;
if (n - r > r) {
minDenom = r;
maxDenom = n - r;
} else {
minDenom = n - r;
maxDenom = r;
}
int val = 1;
int j = 1;
for (int i = n; i > maxDenom; i--) {
val *= i;
if (j <= minDenom) {
val /= j;
j++;
}
}
while (j <= minDenom) {
val /= j;
j++;
}
return val;
}
int GetValue(ArrayView<int> widths, int maxWidth, bool noNarrow)
{
int elements = Size(widths);
int n = Reduce(widths);
int val = 0;
int narrowMask = 0;
for (int bar = 0; bar < elements - 1; bar++) {
int elmWidth;
for (elmWidth = 1, narrowMask |= 1 << bar; elmWidth < widths[bar]; elmWidth++, narrowMask &= ~(1 << bar)) {
int subVal = combins(n - elmWidth - 1, elements - bar - 2);
if (noNarrow && (narrowMask == 0) && (n - elmWidth - (elements - bar - 1) >= elements - bar - 1)) {
subVal -= combins(n - elmWidth - (elements - bar), elements - bar - 2);
}
if (elements - bar - 1 > 1) {
int lessVal = 0;
for (int mxwElement = n - elmWidth - (elements - bar - 2); mxwElement > maxWidth; mxwElement--) {
lessVal += combins(n - elmWidth - mxwElement - 1, elements - bar - 3);
}
subVal -= lessVal * (elements - 1 - bar);
} else if (n - elmWidth > maxWidth) {
subVal--;
}
val += subVal;
}
n -= elmWidth;
}
return val;
}
using Array4F = std::array<float, 4>;
bool ReadDataCharacterRaw(const PatternView& view, int numModules, bool reversed, Array4I& oddPattern,
Array4I& evnPattern)
{
#if 1
auto pattern = NormalizedPatternFromE2E<8>(view, numModules, reversed);
OddEven<Array4I&> res = {oddPattern, evnPattern};
for (int i = 0; i < Size(pattern); ++i)
res[i % 2][i / 2] = pattern[i];
#else
OddEven<Array4I&> res = {oddPattern, evnPattern};
OddEven<Array4F> rem;
float moduleSize = static_cast<float>(view.sum(8)) / numModules;
auto* iter = view.data() + reversed * 7;
int inc = reversed ? -1 : 1;
for (int i = 0; i < 8; ++i, iter += inc) {
float v = *iter / moduleSize;
res[i % 2][i / 2] = int(v + .5f);
rem[i % 2][i / 2] = v - res[i % 2][i / 2];
}
#endif
// DataBarExpanded data character is 17 modules wide
// DataBar outer data character is 16 modules wide
// DataBar inner data character is 15 modules wide
int minSum = 4; // each data character has 4 bars and 4 spaces
int maxSum = numModules - minSum;
int oddSum = Reduce(res.odd);
int evnSum = Reduce(res.evn);
int sumErr = oddSum + evnSum - numModules;
// sum < min -> negative error; sum > max -> positive error
int oddSumErr = std::min(0, oddSum - (minSum + (numModules == 15))) + std::max(0, oddSum - maxSum);
int evnSumErr = std::min(0, evnSum - minSum) + std::max(0, evnSum - (maxSum - (numModules == 15)));
int oddParityErr = (oddSum & 1) == (numModules > 15);
int evnParityErr = (evnSum & 1) == (numModules < 17);
#if 0
// the 'signal improving' strategy of trying to fix off-by-one errors in the sum or parity leads to a massively
// increased likelihood of false positives / misreads especially with expanded codes that are composed of many
// pairs. the combinatorial explosion of possible pair combinations (see FindValidSequence) results in many possible
// sequences with valid checksums. It can slightly lower the minimum required resolution to detect something at all
// but the introduced error rate is clearly not worth it.
if ((sumErr == 0 && oddParityErr != evnParityErr) || (std::abs(sumErr) == 1 && oddParityErr == evnParityErr) ||
std::abs(sumErr) > 1 || std::abs(oddSumErr) > 1 || std::abs(evnSumErr) > 1)
return {};
if (sumErr == -1) {
oddParityErr *= -1;
evnParityErr *= -1;
} else if (sumErr == 0 && oddParityErr != 0) {
// both parity errors are 1 -> flip one of them
(oddSum < evnSum ? oddParityErr : evnParityErr) *= -1;
}
// check if parity and sum errors have opposite signs
if (oddParityErr * oddSumErr < 0 || evnParityErr * evnSumErr < 0)
return {};
// apparently the spec calls numbers at even indices 'odd'!?!
constexpr int odd = 0, evn = 1;
for (int i : {odd, evn}) {
int err = i == odd ? (oddSumErr | oddParityErr) : (evnSumErr | evnParityErr);
int mi = err < 0 ? std::max_element(rem[i].begin(), rem[i].end()) - rem[i].begin()
: std::min_element(rem[i].begin(), rem[i].end()) - rem[i].begin();
res[i][mi] -= err;
}
return true;
#else
// instead, we ignore any character that is not exactly fitting the requirements
return !(sumErr || oddSumErr || evnSumErr || oddParityErr || evnParityErr);
#endif
}
static bool IsStacked(const Pair& first, const Pair& last)
{
// check if we see two halfes that are far away from each other in y or overlapping in x
return std::abs(first.y - last.y) > (first.xStop - first.xStart) || last.xStart < (first.xStart + first.xStop) / 2;
}
Position EstimatePosition(const Pair& first, const Pair& last)
{
if (!IsStacked(first, last))
return Line((first.y + last.y) / 2, first.xStart, last.xStop);
else
return Position{{first.xStart, first.y}, {first.xStop, first.y}, {last.xStop, last.y}, {last.xStart, last.y}};
}
int EstimateLineCount(const Pair& first, const Pair& last)
{
// see incrementLineCount() in ODReader.cpp for the -1 here
return std::min(first.count, last.count) - 1 + IsStacked(first, last);
}
} // namespace ZXing::OneD::DataBar