@zxing/library
Version:
TypeScript port of ZXing multi-format 1D/2D barcode image processing library.
272 lines (271 loc) • 10.7 kB
JavaScript
import { ECIEncoderSet } from './ECIEncoderSet';
import Integer from '../util/Integer';
import StringBuilder from '../util/StringBuilder';
const COST_PER_ECI = 3; // approximated (latch + 2 codewords)
export class MinimalECIInput {
/**
* Constructs a minimal input
*
* @param stringToEncode the character string to encode
* @param priorityCharset The preferred {@link Charset}. When the value of the argument is null, the algorithm
* chooses charsets that leads to a minimal representation. Otherwise the algorithm will use the priority
* charset to encode any character in the input that can be encoded by it if the charset is among the
* supported charsets.
* @param fnc1 denotes the character in the input that represents the FNC1 character or -1 if this is not GS1
* input.
*/
constructor(stringToEncode, priorityCharset, fnc1) {
this.fnc1 = fnc1;
const encoderSet = new ECIEncoderSet(stringToEncode, priorityCharset, fnc1);
if (encoderSet.length() === 1) {
// optimization for the case when all can be encoded without ECI in ISO-8859-1
for (let i = 0; i < this.bytes.length; i++) {
const c = stringToEncode.charAt(i).charCodeAt(0);
this.bytes[i] = c === fnc1 ? 1000 : c;
}
}
else {
this.bytes = this.encodeMinimally(stringToEncode, encoderSet, fnc1);
}
}
getFNC1Character() {
return this.fnc1;
}
/**
* Returns the length of this input. The length is the number
* of {@code byte}s, FNC1 characters or ECIs in the sequence.
*
* @return the number of {@code char}s in this sequence
*/
length() {
return this.bytes.length;
}
haveNCharacters(index, n) {
if (index + n - 1 >= this.bytes.length) {
return false;
}
for (let i = 0; i < n; i++) {
if (this.isECI(index + i)) {
return false;
}
}
return true;
}
/**
* Returns the {@code byte} value at the specified index. An index ranges from zero
* to {@code length() - 1}. The first {@code byte} value of the sequence is at
* index zero, the next at index one, and so on, as for array
* indexing.
*
* @param index the index of the {@code byte} value to be returned
*
* @return the specified {@code byte} value as character or the FNC1 character
*
* @throws IndexOutOfBoundsException
* if the {@code index} argument is negative or not less than
* {@code length()}
* @throws IllegalArgumentException
* if the value at the {@code index} argument is an ECI (@see #isECI)
*/
charAt(index) {
if (index < 0 || index >= this.length()) {
throw new Error('' + index);
}
if (this.isECI(index)) {
throw new Error('value at ' + index + ' is not a character but an ECI');
}
return this.isFNC1(index) ? this.fnc1 : this.bytes[index];
}
/**
* Returns a {@code CharSequence} that is a subsequence of this sequence.
* The subsequence starts with the {@code char} value at the specified index and
* ends with the {@code char} value at index {@code end - 1}. The length
* (in {@code char}s) of the
* returned sequence is {@code end - start}, so if {@code start == end}
* then an empty sequence is returned.
*
* @param start the start index, inclusive
* @param end the end index, exclusive
*
* @return the specified subsequence
*
* @throws IndexOutOfBoundsException
* if {@code start} or {@code end} are negative,
* if {@code end} is greater than {@code length()},
* or if {@code start} is greater than {@code end}
* @throws IllegalArgumentException
* if a value in the range {@code start}-{@code end} is an ECI (@see #isECI)
*/
subSequence(start, end) {
if (start < 0 || start > end || end > this.length()) {
throw new Error('' + start);
}
const result = new StringBuilder();
for (let i = start; i < end; i++) {
if (this.isECI(i)) {
throw new Error('value at ' + i + ' is not a character but an ECI');
}
result.append(this.charAt(i));
}
return result.toString();
}
/**
* Determines if a value is an ECI
*
* @param index the index of the value
*
* @return true if the value at position {@code index} is an ECI
*
* @throws IndexOutOfBoundsException
* if the {@code index} argument is negative or not less than
* {@code length()}
*/
isECI(index) {
if (index < 0 || index >= this.length()) {
throw new Error('' + index);
}
return this.bytes[index] > 255 && this.bytes[index] <= 999;
}
/**
* Determines if a value is the FNC1 character
*
* @param index the index of the value
*
* @return true if the value at position {@code index} is the FNC1 character
*
* @throws IndexOutOfBoundsException
* if the {@code index} argument is negative or not less than
* {@code length()}
*/
isFNC1(index) {
if (index < 0 || index >= this.length()) {
throw new Error('' + index);
}
return this.bytes[index] === 1000;
}
/**
* Returns the {@code int} ECI value at the specified index. An index ranges from zero
* to {@code length() - 1}. The first {@code byte} value of the sequence is at
* index zero, the next at index one, and so on, as for array
* indexing.
*
* @param index the index of the {@code int} value to be returned
*
* @return the specified {@code int} ECI value.
* The ECI specified the encoding of all bytes with a higher index until the
* next ECI or until the end of the input if no other ECI follows.
*
* @throws IndexOutOfBoundsException
* if the {@code index} argument is negative or not less than
* {@code length()}
* @throws IllegalArgumentException
* if the value at the {@code index} argument is not an ECI (@see #isECI)
*/
getECIValue(index) {
if (index < 0 || index >= this.length()) {
throw new Error('' + index);
}
if (!this.isECI(index)) {
throw new Error('value at ' + index + ' is not an ECI but a character');
}
return this.bytes[index] - 256;
}
addEdge(edges, to, edge) {
if (edges[to][edge.encoderIndex] == null ||
edges[to][edge.encoderIndex].cachedTotalSize > edge.cachedTotalSize) {
edges[to][edge.encoderIndex] = edge;
}
}
addEdges(stringToEncode, encoderSet, edges, from, previous, fnc1) {
const ch = stringToEncode.charAt(from).charCodeAt(0);
let start = 0;
let end = encoderSet.length();
if (encoderSet.getPriorityEncoderIndex() >= 0 &&
(ch === fnc1 ||
encoderSet.canEncode(ch, encoderSet.getPriorityEncoderIndex()))) {
start = encoderSet.getPriorityEncoderIndex();
end = start + 1;
}
for (let i = start; i < end; i++) {
if (ch === fnc1 || encoderSet.canEncode(ch, i)) {
this.addEdge(edges, from + 1, new InputEdge(ch, encoderSet, i, previous, fnc1));
}
}
}
encodeMinimally(stringToEncode, encoderSet, fnc1) {
const inputLength = stringToEncode.length;
// Array that represents vertices. There is a vertex for every character and encoding.
const edges = new InputEdge[inputLength + 1][encoderSet.length()]();
this.addEdges(stringToEncode, encoderSet, edges, 0, null, fnc1);
for (let i = 1; i <= inputLength; i++) {
for (let j = 0; j < encoderSet.length(); j++) {
if (edges[i][j] != null && i < inputLength) {
this.addEdges(stringToEncode, encoderSet, edges, i, edges[i][j], fnc1);
}
}
// optimize memory by removing edges that have been passed.
for (let j = 0; j < encoderSet.length(); j++) {
edges[i - 1][j] = null;
}
}
let minimalJ = -1;
let minimalSize = Integer.MAX_VALUE;
for (let j = 0; j < encoderSet.length(); j++) {
if (edges[inputLength][j] != null) {
const edge = edges[inputLength][j];
if (edge.cachedTotalSize < minimalSize) {
minimalSize = edge.cachedTotalSize;
minimalJ = j;
}
}
}
if (minimalJ < 0) {
throw new Error('Failed to encode "' + stringToEncode + '"');
}
const intsAL = [];
let current = edges[inputLength][minimalJ];
while (current != null) {
if (current.isFNC1()) {
intsAL.unshift(1000);
}
else {
const bytes = encoderSet.encode(current.c, current.encoderIndex);
for (let i = bytes.length - 1; i >= 0; i--) {
intsAL.unshift(bytes[i] & 0xff);
}
}
const previousEncoderIndex = current.previous === null ? 0 : current.previous.encoderIndex;
if (previousEncoderIndex !== current.encoderIndex) {
intsAL.unshift(256 + encoderSet.getECIValue(current.encoderIndex));
}
current = current.previous;
}
const ints = [];
for (let i = 0; i < ints.length; i++) {
ints[i] = intsAL[i];
}
return ints;
}
}
class InputEdge {
constructor(c, encoderSet, encoderIndex, previous, fnc1) {
this.c = c;
this.encoderSet = encoderSet;
this.encoderIndex = encoderIndex;
this.previous = previous;
this.fnc1 = fnc1;
this.c = c === fnc1 ? 1000 : c;
let size = this.isFNC1() ? 1 : encoderSet.encode(c, encoderIndex).length;
const previousEncoderIndex = previous === null ? 0 : previous.encoderIndex;
if (previousEncoderIndex !== encoderIndex) {
size += COST_PER_ECI;
}
if (previous != null) {
size += previous.cachedTotalSize;
}
this.cachedTotalSize = size;
}
isFNC1() {
return this.c === 1000;
}
}