zxing-js/library

/*
 * Copyright 2008 ZXing authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import BarcodeFormat from '../BarcodeFormat';
import BitArray from '../common/BitArray';

import UPCEANReader from './UPCEANReader';

/**
 * <p>Implements decoding of the EAN-8 format.</p>
 *
 * @author Sean Owen
 */
export default class EAN8Reader extends UPCEANReader {
    private decodeMiddleCounters: Int32Array;

    public constructor() {
        super();
        this.decodeMiddleCounters = Int32Array.from([0, 0, 0, 0]);
    }

    public decodeMiddle(row: BitArray, startRange: Int32Array, resultString: string) {
        const counters = this.decodeMiddleCounters;
        counters[0] = 0;
        counters[1] = 0;
        counters[2] = 0;
        counters[3] = 0;
        let end = row.getSize();
        let rowOffset = startRange[1];

        for (let x = 0; x < 4 && rowOffset < end; x++) {
            let bestMatch = UPCEANReader.decodeDigit(row, counters, rowOffset, UPCEANReader.L_PATTERNS);
            resultString += String.fromCharCode(('0'.charCodeAt(0) + bestMatch));

            for (let counter of counters) {
                rowOffset += counter;
            }
        }

        let middleRange = UPCEANReader.findGuardPattern(row, rowOffset, true, UPCEANReader.MIDDLE_PATTERN, new Int32Array(UPCEANReader.MIDDLE_PATTERN.length).fill(0));
        rowOffset = middleRange[1];

        for (let x = 0; x < 4 && rowOffset < end; x++) {
            let bestMatch = UPCEANReader.decodeDigit(row, counters, rowOffset, UPCEANReader.L_PATTERNS);
            resultString += String.fromCharCode(('0'.charCodeAt(0) + bestMatch));

            for (let counter of counters) {
                rowOffset += counter;
            }
        }

        return {rowOffset, resultString};
    }

    public getBarcodeFormat(): BarcodeFormat {
        return BarcodeFormat.EAN_8;
    }
}