Initial commit on EAN supplements; Relates to #71

src/reader/barcode_reader.js

@@ -1,6 +1,7 @@
-function BarcodeReader(config) {
+function BarcodeReader(config, supplements) {
     this._row = [];
     this.config = config || {};
+    this.supplements = supplements;
     return this;
 }
 

src/reader/ean_2_reader.js

@@ -0,0 +1,46 @@
+import EANReader from './ean_reader';
+
+function EAN2Reader() {
+    EANReader.call(this);
+}
+
+var properties = {
+    FORMAT: {value: "ean_2", writeable: false}
+};
+
+EAN2Reader.prototype = Object.create(EANReader.prototype, properties);
+EAN2Reader.prototype.constructor = EAN2Reader;
+
+EAN2Reader.prototype.decode = function(row, start) {
+    this._row = row;
+    var counters = [0, 0, 0, 0],
+        codeFrequency = 0,
+        i = 0,
+        offset = start,
+        end = this._row.length,
+        code,
+        result = [];
+
+    for (i = 0; i < 2 && offset < end; i++) {
+        code = this._decodeCode(offset);
+        if (!code) {
+            return null;
+        }
+        result.push(code.code % 10);
+        if (code.code >= this.CODE_G_START) {
+            codeFrequency |= 1 << (1 - i);
+        }
+        if (i != 1) {
+            offset = this._nextSet(this._row, code.end);
+            offset = this._nextUnset(this._row, offset);
+        }
+    }
+
+    if (result.length != 2 || (result.reduce((sum, i) => sum + i, 0) % 4  !== codeFrequency)) {
+        return null;
+    }
+    console.log(result);
+    return offset;
+};
+
+export default EAN2Reader;

src/reader/ean_5_reader.js

@@ -0,0 +1,79 @@
+import EANReader from './ean_reader';
+
+function EAN5Reader() {
+    EANReader.call(this);
+}
+
+var properties = {
+    FORMAT: {value: "ean_5", writeable: false}
+};
+
+const CHECK_DIGIT_ENCODINGS = [24, 20, 18, 17, 12, 6, 3, 10, 9, 5];
+
+EAN5Reader.prototype = Object.create(EANReader.prototype, properties);
+EAN5Reader.prototype.constructor = EAN5Reader;
+
+EAN5Reader.prototype.decode = function(row, start) {
+    this._row = row;
+    var counters = [0, 0, 0, 0],
+        codeFrequency = 0,
+        i = 0,
+        offset = start,
+        end = this._row.length,
+        code,
+        result = [];
+
+    for (i = 0; i < 5 && offset < end; i++) {
+        code = this._decodeCode(offset);
+        if (!code) {
+            return null;
+        }
+        result.push(code.code % 10);
+        if (code.code >= this.CODE_G_START) {
+            codeFrequency |= 1 << (4 - i);
+        }
+        if (i != 4) {
+            offset = this._nextSet(this._row, code.end);
+            offset = this._nextUnset(this._row, offset);
+        }
+    }
+
+    if (result.length != 5) {
+        return null;
+    }
+
+    if (extensionChecksum(result) !== determineCheckDigit(codeFrequency)) {
+        return null;
+    }
+    console.log(result);
+    return offset;
+};
+
+function determineCheckDigit(codeFrequency) {
+    var i;
+    for (i = 0; i < 10; i++) {
+        if (codeFrequency === CHECK_DIGIT_ENCODINGS[i]) {
+            return i;
+        }
+    }
+    return null;
+}
+
+
+function extensionChecksum(result) {
+    var length = result.length,
+        sum = 0,
+        i;
+
+    for (i = length - 2; i >= 0; i -= 2) {
+        sum += result[i];
+    }
+    sum *= 3;
+    for (i = length - 1; i >= 0; i -= 2) {
+        sum += result[i];
+    }
+    sum *= 3;
+    return sum % 10;
+}
+
+export default EAN5Reader;

src/reader/ean_reader.js

@@ -1,7 +1,18 @@
 import BarcodeReader from './barcode_reader';
+import {merge} from 'lodash';
 
-function EANReader(opts) {
-    BarcodeReader.call(this, opts);
+function EANReader(opts, supplements) {
+    opts = merge(getDefaulConfig(), opts);
+    BarcodeReader.call(this, opts, supplements);
+}
+
+function getDefaulConfig() {
+    var config = {};
+
+    Object.keys(EANReader.CONFIG_KEYS).forEach(function(key) {
+        config[key] = EANReader.CONFIG_KEYS[key].default;
+    });
+    return config;
 }
 
 var properties = {
@@ -11,6 +22,7 @@ var properties = {
     START_PATTERN: {value: [1 / 3 * 7, 1 / 3 * 7, 1 / 3 * 7]},
     STOP_PATTERN: {value: [1 / 3 * 7, 1 / 3 * 7, 1 / 3 * 7]},
     MIDDLE_PATTERN: {value: [1 / 5 * 7, 1 / 5 * 7, 1 / 5 * 7, 1 / 5 * 7, 1 / 5 * 7]},
+    EXTENSION_START_PATTERN: {value: [1 / 4 * 7, 1 / 4 * 7, 2 / 4 * 7]},
     CODE_PATTERN: {value: [
         [3, 2, 1, 1],
         [2, 2, 2, 1],
@@ -301,6 +313,13 @@ EANReader.prototype._decode = function() {
         return null;
     }
 
+    if (this.supplements.length > 0) {
+        let ext = this._decodeExtensions(code.end);
+        if (!ext) {
+            return null;
+        }
+    }
+
     return {
         code: result.join(""),
         start: startInfo.start,
@@ -311,6 +330,25 @@ EANReader.prototype._decode = function() {
     };
 };
 
+EANReader.prototype._decodeExtensions = function(offset) {
+    var i,
+        start = this._nextSet(this._row, offset),
+        code = this._findPattern(this.EXTENSION_START_PATTERN, start, false, false),
+        result;
+
+    if (code === null) {
+        return null;
+    }
+
+    for (i = 0; i < this.supplements.length; i++) {
+        result = this.supplements[i].decode(this._row, code.end);
+        if (result !== null) {
+            return result;
+        }
+    }
+    return null;
+};
+
 EANReader.prototype._checksum = function(result) {
     var sum = 0, i;
 
@@ -324,4 +362,12 @@ EANReader.prototype._checksum = function(result) {
     return sum % 10 === 0;
 };
 
+EANReader.CONFIG_KEYS = {
+    supplements: {
+        'type': 'arrayOf(string)',
+        'default': [],
+        'description': 'Allowed extensions to be decoded (2 and/or 5)'
+    }
+};
+
 export default (EANReader);