Added basic support for Code 39 barcodes
Christoph Oberhofer
11 years ago
parent
3c4a108a4a
commit
7638bc41eb
@ -0,0 +1,186 @@
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/* jshint undef: true, unused: true, browser:true, devel: true */
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/* global define */
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define(
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[
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"./barcode_reader",
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"./array_helper"
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],
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function(BarcodeReader, ArrayHelper) {
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"use strict";
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function Code39Reader() {
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BarcodeReader.call(this);
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}
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var properties = {
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ALPHABETH_STRING: {value: "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ-. *$/+%"},
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ALPHABET: {value: [48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 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, 45, 46, 32, 42, 36, 47, 43, 37]},
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CHARACTER_ENCODINGS: {value: [0x034, 0x121, 0x061, 0x160, 0x031, 0x130, 0x070, 0x025, 0x124, 0x064, 0x109, 0x049, 0x148, 0x019, 0x118, 0x058, 0x00D, 0x10C, 0x04C, 0x01C, 0x103, 0x043, 0x142, 0x013, 0x112, 0x052, 0x007, 0x106, 0x046, 0x016, 0x181, 0x0C1, 0x1C0, 0x091, 0x190, 0x0D0, 0x085, 0x184, 0x0C4, 0x094, 0x0A8, 0x0A2, 0x08A, 0x02A]},
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ASTERISK: {value: 0x094}
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};
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Code39Reader.prototype = Object.create(BarcodeReader.prototype, properties);
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Code39Reader.prototype.constructor = Code39Reader;
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Code39Reader.prototype._toCounters = function(start, counter) {
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var self = this,
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numCounters = counter.length,
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end = self._row.length,
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isWhite = !self._row[start],
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i,
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counterPos = 0;
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ArrayHelper.init(counter, 0);
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for ( i = start; i < end; i++) {
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if (self._row[i] ^ isWhite) {
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counter[counterPos]++;
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} else {
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counterPos++;
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if (counterPos === numCounters) {
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break;
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} else {
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counter[counterPos] = 1;
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isWhite = !isWhite;
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}
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}
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}
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return counter;
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};
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Code39Reader.prototype._decode = function() {
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var self = this,
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counters = [0,0,0,0,0,0,0,0,0],
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result = [],
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start = self._findStart(),
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decodedChar,
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lastStart,
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pattern,
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nextStart;
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if (!start) {
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return null;
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}
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nextStart = self._nextSet(self._row, start.end);
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do {
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counters = self._toCounters(nextStart, counters);
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pattern = self._toPattern(counters);
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if (pattern < 0) {
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return null;
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}
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decodedChar = self._patternToChar(pattern);
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result.push(decodedChar);
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lastStart = nextStart;
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nextStart += ArrayHelper.sum(counters);
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nextStart = self._nextSet(self._row, nextStart);
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} while(decodedChar !== '*');
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result.pop();
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return {
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code : result.join(""),
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start : start.start,
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end : nextStart,
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startInfo : start,
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decodedCodes : result
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};
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};
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Code39Reader.prototype._patternToChar = function(pattern) {
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var i,
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self = this;
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for (i = 0; i < self.CHARACTER_ENCODINGS.length; i++) {
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if (self.CHARACTER_ENCODINGS[i] === pattern) {
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return String.fromCharCode(self.ALPHABET[i]);
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}
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}
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};
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Code39Reader.prototype._findNextWidth = function(counters, current) {
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var i,
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minWidth = Number.MAX_VALUE;
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for (i = 0; i < counters.length; i++) {
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if (counters[i] < minWidth && counters[i] > current) {
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minWidth = counters[i];
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}
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}
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return minWidth;
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};
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Code39Reader.prototype._toPattern = function(counters) {
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var numCounters = counters.length,
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maxNarrowWidth = 0,
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numWideBars = numCounters,
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self = this,
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pattern,
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i;
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while(numWideBars > 3) {
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maxNarrowWidth = self._findNextWidth(counters, maxNarrowWidth);
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numWideBars = 0;
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pattern = 0;
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for (i = 0; i < numCounters; i++) {
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if (counters[i] > maxNarrowWidth) {
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pattern |= 1 << (numCounters - 1 - i);
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numWideBars++;
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}
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}
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if (numWideBars === 3) {
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return pattern;
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}
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}
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return -1;
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};
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Code39Reader.prototype._findEnd = function() {
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};
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Code39Reader.prototype._findStart = function() {
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var self = this,
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offset = self._nextSet(self._row),
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patternStart = offset,
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counter = [0,0,0,0,0,0,0,0,0],
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counterPos = 0,
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isWhite = false,
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i,
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j;
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for ( i = offset; i < self._row.length; i++) {
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if (self._row[i] ^ isWhite) {
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counter[counterPos]++;
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} else {
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if (counterPos === counter.length - 1) {
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// find start pattern
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if (self._toPattern(counter) === self.ASTERISK) {
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return {
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start: patternStart,
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end: i
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};
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}
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patternStart += counter[0] + counter[1];
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for ( j = 0; j < 7; j++) {
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counter[j] = counter[j + 2];
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}
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counter[7] = 0;
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counter[8] = 0;
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counterPos--;
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} else {
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counterPos++;
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}
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counter[counterPos] = 1;
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isWhite = !isWhite;
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}
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}
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return null;
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};
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return (Code39Reader);
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}
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);
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