@zxing/library
Version:
TypeScript port of ZXing multi-format 1D/2D barcode image processing library.
196 lines (195 loc) • 7.59 kB
JavaScript
import StringBuilder from '../../util/StringBuilder';
import HighLevelEncoder from './HighLevelEncoder';
import { C40_ENCODATION, LATCH_TO_C40, ASCII_ENCODATION, C40_UNLATCH, } from './constants';
export class C40Encoder {
getEncodingMode() {
return C40_ENCODATION;
}
encodeMaximal(context) {
const buffer = new StringBuilder();
let lastCharSize = 0;
let backtrackStartPosition = context.pos;
let backtrackBufferLength = 0;
while (context.hasMoreCharacters()) {
const c = context.getCurrentChar();
context.pos++;
lastCharSize = this.encodeChar(c, buffer);
if (buffer.length() % 3 === 0) {
backtrackStartPosition = context.pos;
backtrackBufferLength = buffer.length();
}
}
if (backtrackBufferLength !== buffer.length()) {
const unwritten = Math.floor((buffer.length() / 3) * 2);
const curCodewordCount = Math.floor(context.getCodewordCount() + unwritten + 1); // +1 for the latch to C40
context.updateSymbolInfo(curCodewordCount);
const available = context.getSymbolInfo().getDataCapacity() - curCodewordCount;
const rest = Math.floor(buffer.length() % 3);
if ((rest === 2 && available !== 2) ||
(rest === 1 && (lastCharSize > 3 || available !== 1))) {
// buffer.setLength(backtrackBufferLength);
context.pos = backtrackStartPosition;
}
}
if (buffer.length() > 0) {
context.writeCodeword(LATCH_TO_C40);
}
this.handleEOD(context, buffer);
}
encode(context) {
// step C
const buffer = new StringBuilder();
while (context.hasMoreCharacters()) {
const c = context.getCurrentChar();
context.pos++;
let lastCharSize = this.encodeChar(c, buffer);
const unwritten = Math.floor(buffer.length() / 3) * 2;
const curCodewordCount = context.getCodewordCount() + unwritten;
context.updateSymbolInfo(curCodewordCount);
const available = context.getSymbolInfo().getDataCapacity() - curCodewordCount;
if (!context.hasMoreCharacters()) {
// Avoid having a single C40 value in the last triplet
const removed = new StringBuilder();
if (buffer.length() % 3 === 2 && available !== 2) {
lastCharSize = this.backtrackOneCharacter(context, buffer, removed, lastCharSize);
}
while (buffer.length() % 3 === 1 &&
(lastCharSize > 3 || available !== 1)) {
lastCharSize = this.backtrackOneCharacter(context, buffer, removed, lastCharSize);
}
break;
}
const count = buffer.length();
if (count % 3 === 0) {
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;
}
}
}
this.handleEOD(context, buffer);
}
backtrackOneCharacter(context, buffer, removed, lastCharSize) {
const count = buffer.length();
const test = buffer.toString().substring(0, count - lastCharSize);
buffer.setLengthToZero();
buffer.append(test);
// buffer.delete(count - lastCharSize, count);
/*for (let i = count - lastCharSize; i < count; i++) {
buffer.deleteCharAt(i);
}*/
context.pos--;
const c = context.getCurrentChar();
lastCharSize = this.encodeChar(c, removed);
context.resetSymbolInfo(); // Deal with possible reduction in symbol size
return lastCharSize;
}
writeNextTriplet(context, buffer) {
context.writeCodewords(this.encodeToCodewords(buffer.toString()));
const test = buffer.toString().substring(3);
buffer.setLengthToZero();
buffer.append(test);
// buffer.delete(0, 3);
/*for (let i = 0; i < 3; i++) {
buffer.deleteCharAt(i);
}*/
}
/**
* Handle "end of data" situations
*
* @param context the encoder context
* @param buffer the buffer with the remaining encoded characters
*/
handleEOD(context, buffer) {
const unwritten = Math.floor((buffer.length() / 3) * 2);
const rest = buffer.length() % 3;
const curCodewordCount = context.getCodewordCount() + unwritten;
context.updateSymbolInfo(curCodewordCount);
const available = context.getSymbolInfo().getDataCapacity() - curCodewordCount;
if (rest === 2) {
buffer.append('\0'); // Shift 1
while (buffer.length() >= 3) {
this.writeNextTriplet(context, buffer);
}
if (context.hasMoreCharacters()) {
context.writeCodeword(C40_UNLATCH);
}
}
else if (available === 1 && rest === 1) {
while (buffer.length() >= 3) {
this.writeNextTriplet(context, buffer);
}
if (context.hasMoreCharacters()) {
context.writeCodeword(C40_UNLATCH);
}
// else no unlatch
context.pos--;
}
else if (rest === 0) {
while (buffer.length() >= 3) {
this.writeNextTriplet(context, buffer);
}
if (available > 0 || context.hasMoreCharacters()) {
context.writeCodeword(C40_UNLATCH);
}
}
else {
throw new Error('Unexpected case. Please report!');
}
context.signalEncoderChange(ASCII_ENCODATION);
}
encodeChar(c, sb) {
if (c === ' '.charCodeAt(0)) {
sb.append(0o3);
return 1;
}
if (c >= '0'.charCodeAt(0) && c <= '9'.charCodeAt(0)) {
sb.append(c - 48 + 4);
return 1;
}
if (c >= 'A'.charCodeAt(0) && c <= 'Z'.charCodeAt(0)) {
sb.append(c - 65 + 14);
return 1;
}
if (c < ' '.charCodeAt(0)) {
sb.append(0o0); // Shift 1 Set
sb.append(c);
return 2;
}
if (c <= '/'.charCodeAt(0)) {
sb.append(0o1); // Shift 2 Set
sb.append(c - 33);
return 2;
}
if (c <= '@'.charCodeAt(0)) {
sb.append(0o1); // Shift 2 Set
sb.append(c - 58 + 15);
return 2;
}
if (c <= '_'.charCodeAt(0)) {
sb.append(0o1); // Shift 2 Set
sb.append(c - 91 + 22);
return 2;
}
if (c <= 127) {
sb.append(0o2); // Shift 3 Set
sb.append(c - 96);
return 2;
}
sb.append(`${0o1}\u001e`); // Shift 2, Upper Shift
let len = 2;
len += this.encodeChar(c - 128, sb);
return len;
}
encodeToCodewords(sb) {
const v = 1600 * sb.charCodeAt(0) + 40 * sb.charCodeAt(1) + sb.charCodeAt(2) + 1;
const cw1 = v / 256;
const cw2 = v % 256;
const result = new StringBuilder();
result.append(cw1);
result.append(cw2);
return result.toString();
}
}