@zxing/library/es2015/core/datamatrix/encoder/EdifactEncoder.js

TypeScript port of ZXing multi-format 1D/2D barcode image processing library.

import StringUtils from '../../common/StringUtils';
import StringBuilder from '../../util/StringBuilder';
import { EDIFACT_ENCODATION, ASCII_ENCODATION } from './constants';
import HighLevelEncoder from './HighLevelEncoder';
export class EdifactEncoder {
    getEncodingMode() {
        return EDIFACT_ENCODATION;
    }
    encode(context) {
        // step F
        const buffer = new StringBuilder();
        while (context.hasMoreCharacters()) {
            const c = context.getCurrentChar();
            this.encodeChar(c, buffer);
            context.pos++;
            const count = buffer.length();
            if (count >= 4) {
                context.writeCodewords(this.encodeToCodewords(buffer.toString()));
                const test = buffer.toString().substring(4);
                buffer.setLengthToZero();
                buffer.append(test);
                // buffer.delete(0, 4);
                // for (let i = 0; i < 4; i++) {
                //  buffer.deleteCharAt(i);
                // }
                const newMode = HighLevelEncoder.lookAheadTest(context.getMessage(), context.pos, this.getEncodingMode());
                if (newMode !== this.getEncodingMode()) {
                    // Return to ASCII encodation, which will actually handle latch to new mode
                    context.signalEncoderChange(ASCII_ENCODATION);
                    break;
                }
            }
        }
        buffer.append(StringUtils.getCharAt(31)); // Unlatch
        this.handleEOD(context, buffer);
    }
    /**
     * Handle "end of data" situations
     *
     * @param context the encoder context
     * @param buffer  the buffer with the remaining encoded characters
     */
    handleEOD(context, buffer) {
        try {
            const count = buffer.length();
            if (count === 0) {
                return; // Already finished
            }
            if (count === 1) {
                // Only an unlatch at the end
                context.updateSymbolInfo();
                let available = context.getSymbolInfo().getDataCapacity() -
                    context.getCodewordCount();
                const remaining = context.getRemainingCharacters();
                // The following two lines are a hack inspired by the 'fix' from https://sourceforge.net/p/barcode4j/svn/221/
                if (remaining > available) {
                    context.updateSymbolInfo(context.getCodewordCount() + 1);
                    available =
                        context.getSymbolInfo().getDataCapacity() -
                            context.getCodewordCount();
                }
                if (remaining <= available && available <= 2) {
                    return; // No unlatch
                }
            }
            if (count > 4) {
                throw new Error('Count must not exceed 4');
            }
            const restChars = count - 1;
            const encoded = this.encodeToCodewords(buffer.toString());
            const endOfSymbolReached = !context.hasMoreCharacters();
            let restInAscii = endOfSymbolReached && restChars <= 2;
            if (restChars <= 2) {
                context.updateSymbolInfo(context.getCodewordCount() + restChars);
                const available = context.getSymbolInfo().getDataCapacity() -
                    context.getCodewordCount();
                if (available >= 3) {
                    restInAscii = false;
                    context.updateSymbolInfo(context.getCodewordCount() + encoded.length);
                    // available = context.symbolInfo.dataCapacity - context.getCodewordCount();
                }
            }
            if (restInAscii) {
                context.resetSymbolInfo();
                context.pos -= restChars;
            }
            else {
                context.writeCodewords(encoded);
            }
        }
        finally {
            context.signalEncoderChange(ASCII_ENCODATION);
        }
    }
    encodeChar(c, sb) {
        if (c >= ' '.charCodeAt(0) && c <= '?'.charCodeAt(0)) {
            sb.append(c);
        }
        else if (c >= '@'.charCodeAt(0) && c <= '^'.charCodeAt(0)) {
            sb.append(StringUtils.getCharAt(c - 64));
        }
        else {
            HighLevelEncoder.illegalCharacter(StringUtils.getCharAt(c));
        }
    }
    encodeToCodewords(sb) {
        const len = sb.length;
        if (len === 0) {
            throw new Error('StringBuilder must not be empty');
        }
        const c1 = sb.charAt(0).charCodeAt(0);
        const c2 = len >= 2 ? sb.charAt(1).charCodeAt(0) : 0;
        const c3 = len >= 3 ? sb.charAt(2).charCodeAt(0) : 0;
        const c4 = len >= 4 ? sb.charAt(3).charCodeAt(0) : 0;
        const v = (c1 << 18) + (c2 << 12) + (c3 << 6) + c4;
        const cw1 = (v >> 16) & 255;
        const cw2 = (v >> 8) & 255;
        const cw3 = v & 255;
        const res = new StringBuilder();
        res.append(cw1);
        if (len >= 2) {
            res.append(cw2);
        }
        if (len >= 3) {
            res.append(cw3);
        }
        return res.toString();
    }
}