getuserbarcode
Version:
An advanced barcode-scanner written in JavaScript
326 lines (289 loc) • 8.92 kB
JavaScript
import BarcodeReader from './barcode_reader';
import {merge} from 'lodash';
function I2of5Reader(opts) {
opts = merge(getDefaulConfig(), opts);
BarcodeReader.call(this, opts);
this.barSpaceRatio = [1, 1];
if (opts.normalizeBarSpaceWidth) {
this.SINGLE_CODE_ERROR = 0.38;
this.AVG_CODE_ERROR = 0.09;
}
}
function getDefaulConfig() {
var config = {};
Object.keys(I2of5Reader.CONFIG_KEYS).forEach(function(key) {
config[key] = I2of5Reader.CONFIG_KEYS[key].default;
});
return config;
}
var N = 1,
W = 3,
properties = {
START_PATTERN: {value: [N, N, N, N]},
STOP_PATTERN: {value: [N, N, W]},
CODE_PATTERN: {value: [
[N, N, W, W, N],
[W, N, N, N, W],
[N, W, N, N, W],
[W, W, N, N, N],
[N, N, W, N, W],
[W, N, W, N, N],
[N, W, W, N, N],
[N, N, N, W, W],
[W, N, N, W, N],
[N, W, N, W, N]
]},
SINGLE_CODE_ERROR: {value: 0.78, writable: true},
AVG_CODE_ERROR: {value: 0.38, writable: true},
MAX_CORRECTION_FACTOR: {value: 5},
FORMAT: {value: "i2of5"}
};
I2of5Reader.prototype = Object.create(BarcodeReader.prototype, properties);
I2of5Reader.prototype.constructor = I2of5Reader;
I2of5Reader.prototype._matchPattern = function(counter, code) {
if (this.config.normalizeBarSpaceWidth) {
var i,
counterSum = [0, 0],
codeSum = [0, 0],
correction = [0, 0],
correctionRatio = this.MAX_CORRECTION_FACTOR,
correctionRatioInverse = 1 / correctionRatio;
for (i = 0; i < counter.length; i++) {
counterSum[i % 2] += counter[i];
codeSum[i % 2] += code[i];
}
correction[0] = codeSum[0] / counterSum[0];
correction[1] = codeSum[1] / counterSum[1];
correction[0] = Math.max(Math.min(correction[0], correctionRatio), correctionRatioInverse);
correction[1] = Math.max(Math.min(correction[1], correctionRatio), correctionRatioInverse);
this.barSpaceRatio = correction;
for (i = 0; i < counter.length; i++) {
counter[i] *= this.barSpaceRatio[i % 2];
}
}
return BarcodeReader.prototype._matchPattern.call(this, counter, code);
};
I2of5Reader.prototype._findPattern = function(pattern, offset, isWhite, tryHarder) {
var counter = [],
self = this,
i,
counterPos = 0,
bestMatch = {
error: Number.MAX_VALUE,
code: -1,
start: 0,
end: 0
},
error,
j,
sum,
normalized,
epsilon = self.AVG_CODE_ERROR;
isWhite = isWhite || false;
tryHarder = tryHarder || false;
if (!offset) {
offset = self._nextSet(self._row);
}
for ( i = 0; i < pattern.length; i++) {
counter[i] = 0;
}
for ( i = offset; i < self._row.length; i++) {
if (self._row[i] ^ isWhite) {
counter[counterPos]++;
} else {
if (counterPos === counter.length - 1) {
sum = 0;
for ( j = 0; j < counter.length; j++) {
sum += counter[j];
}
error = self._matchPattern(counter, pattern);
if (error < epsilon) {
bestMatch.error = error;
bestMatch.start = i - sum;
bestMatch.end = i;
return bestMatch;
}
if (tryHarder) {
for (j = 0; j < counter.length - 2; j++) {
counter[j] = counter[j + 2];
}
counter[counter.length - 2] = 0;
counter[counter.length - 1] = 0;
counterPos--;
} else {
return null;
}
} else {
counterPos++;
}
counter[counterPos] = 1;
isWhite = !isWhite;
}
}
return null;
};
I2of5Reader.prototype._findStart = function() {
var self = this,
leadingWhitespaceStart,
offset = self._nextSet(self._row),
startInfo,
narrowBarWidth = 1;
while (!startInfo) {
startInfo = self._findPattern(self.START_PATTERN, offset, false, true);
if (!startInfo) {
return null;
}
narrowBarWidth = Math.floor((startInfo.end - startInfo.start) / 4);
leadingWhitespaceStart = startInfo.start - narrowBarWidth * 10;
if (leadingWhitespaceStart >= 0) {
if (self._matchRange(leadingWhitespaceStart, startInfo.start, 0)) {
return startInfo;
}
}
offset = startInfo.end;
startInfo = null;
}
};
I2of5Reader.prototype._verifyTrailingWhitespace = function(endInfo) {
var self = this,
trailingWhitespaceEnd;
trailingWhitespaceEnd = endInfo.end + ((endInfo.end - endInfo.start) / 2);
if (trailingWhitespaceEnd < self._row.length) {
if (self._matchRange(endInfo.end, trailingWhitespaceEnd, 0)) {
return endInfo;
}
}
return null;
};
I2of5Reader.prototype._findEnd = function() {
var self = this,
endInfo,
tmp;
self._row.reverse();
endInfo = self._findPattern(self.STOP_PATTERN);
self._row.reverse();
if (endInfo === null) {
return null;
}
// reverse numbers
tmp = endInfo.start;
endInfo.start = self._row.length - endInfo.end;
endInfo.end = self._row.length - tmp;
return endInfo !== null ? self._verifyTrailingWhitespace(endInfo) : null;
};
I2of5Reader.prototype._decodePair = function(counterPair) {
var i,
code,
codes = [],
self = this;
for (i = 0; i < counterPair.length; i++) {
code = self._decodeCode(counterPair[i]);
if (!code) {
return null;
}
codes.push(code);
}
return codes;
};
I2of5Reader.prototype._decodeCode = function(counter) {
var j,
self = this,
sum = 0,
normalized,
error,
epsilon = self.AVG_CODE_ERROR,
code,
bestMatch = {
error: Number.MAX_VALUE,
code: -1,
start: 0,
end: 0
};
for ( j = 0; j < counter.length; j++) {
sum += counter[j];
}
for (code = 0; code < self.CODE_PATTERN.length; code++) {
error = self._matchPattern(counter, self.CODE_PATTERN[code]);
if (error < bestMatch.error) {
bestMatch.code = code;
bestMatch.error = error;
}
}
if (bestMatch.error < epsilon) {
return bestMatch;
}
};
I2of5Reader.prototype._decodePayload = function(counters, result, decodedCodes) {
var i,
self = this,
pos = 0,
counterLength = counters.length,
counterPair = [[0, 0, 0, 0, 0], [0, 0, 0, 0, 0]],
codes;
while (pos < counterLength) {
for (i = 0; i < 5; i++) {
counterPair[0][i] = counters[pos] * this.barSpaceRatio[0];
counterPair[1][i] = counters[pos + 1] * this.barSpaceRatio[1];
pos += 2;
}
codes = self._decodePair(counterPair);
if (!codes) {
return null;
}
for (i = 0; i < codes.length; i++) {
result.push(codes[i].code + "");
decodedCodes.push(codes[i]);
}
}
return codes;
};
I2of5Reader.prototype._verifyCounterLength = function(counters) {
return (counters.length % 10 === 0);
};
I2of5Reader.prototype._decode = function() {
var startInfo,
endInfo,
self = this,
code,
result = [],
decodedCodes = [],
counters;
startInfo = self._findStart();
if (!startInfo) {
return null;
}
decodedCodes.push(startInfo);
endInfo = self._findEnd();
if (!endInfo) {
return null;
}
counters = self._fillCounters(startInfo.end, endInfo.start, false);
if (!self._verifyCounterLength(counters)) {
return null;
}
code = self._decodePayload(counters, result, decodedCodes);
if (!code) {
return null;
}
if (result.length % 2 !== 0 ||
result.length < 6) {
return null;
}
decodedCodes.push(endInfo);
return {
code: result.join(""),
start: startInfo.start,
end: endInfo.end,
startInfo: startInfo,
decodedCodes: decodedCodes
};
};
I2of5Reader.CONFIG_KEYS = {
normalizeBarSpaceWidth: {
'type': 'boolean',
'default': false,
'description': 'If true, the reader tries to normalize the' +
'width-difference between bars and spaces'
}
};
export default I2of5Reader;