src/core/qrcode/decoder/DecodedBitStreamParser.ts
/*
* Copyright 2007 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.
*/
/*namespace com.google.zxing.qrcode.decoder {*/
import BitSource from '../../common/BitSource';
import CharacterSetECI from '../../common/CharacterSetECI';
import DecoderResult from '../../common/DecoderResult';
import StringUtils from '../../common/StringUtils';
import DecodeHintType from '../../DecodeHintType';
import FormatException from '../../FormatException';
import StringBuilder from '../../util/StringBuilder';
import StringEncoding from '../../util/StringEncoding';
import ErrorCorrectionLevel from './ErrorCorrectionLevel';
import Mode from './Mode';
import Version from './Version';
/*import java.io.UnsupportedEncodingException;*/
/*import java.util.ArrayList;*/
/*import java.util.Collection;*/
/*import java.util.List;*/
/*import java.util.Map;*/
/**
* <p>QR Codes can encode text as bits in one of several modes, and can use multiple modes
* in one QR Code. This class decodes the bits back into text.</p>
*
* <p>See ISO 18004:2006, 6.4.3 - 6.4.7</p>
*
* @author Sean Owen
*/
export default class DecodedBitStreamParser {
/**
* See ISO 18004:2006, 6.4.4 Table 5
*/
private static ALPHANUMERIC_CHARS =
'0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ $%*+-./:';
private static GB2312_SUBSET = 1;
public static decode(bytes: Uint8Array,
version: Version,
ecLevel: ErrorCorrectionLevel,
hints: Map<DecodeHintType, any>): DecoderResult /*throws FormatException*/ {
const bits = new BitSource(bytes);
let result = new StringBuilder();
const byteSegments = new Array<Uint8Array>(); // 1
// TYPESCRIPTPORT: I do not use constructor with size 1 as in original Java means capacity and the array length is checked below
let symbolSequence = -1;
let parityData = -1;
try {
let currentCharacterSetECI: CharacterSetECI = null;
let fc1InEffect: boolean = false;
let mode: Mode;
do {
// While still another segment to read...
if (bits.available() < 4) {
// OK, assume we're done. Really, a TERMINATOR mode should have been recorded here
mode = Mode.TERMINATOR;
} else {
const modeBits = bits.readBits(4);
mode = Mode.forBits(modeBits); // mode is encoded by 4 bits
}
switch (mode) {
case Mode.TERMINATOR:
break;
case Mode.FNC1_FIRST_POSITION:
case Mode.FNC1_SECOND_POSITION:
// We do little with FNC1 except alter the parsed result a bit according to the spec
fc1InEffect = true;
break;
case Mode.STRUCTURED_APPEND:
if (bits.available() < 16) {
throw new FormatException();
}
// sequence number and parity is added later to the result metadata
// Read next 8 bits (symbol sequence #) and 8 bits (data: parity), then continue
symbolSequence = bits.readBits(8);
parityData = bits.readBits(8);
break;
case Mode.ECI:
// Count doesn't apply to ECI
const value = DecodedBitStreamParser.parseECIValue(bits);
currentCharacterSetECI = CharacterSetECI.getCharacterSetECIByValue(value);
if (currentCharacterSetECI === null) {
throw new FormatException();
}
break;
case Mode.HANZI:
// First handle Hanzi mode which does not start with character count
// Chinese mode contains a sub set indicator right after mode indicator
const subset = bits.readBits(4);
const countHanzi = bits.readBits(mode.getCharacterCountBits(version));
if (subset === DecodedBitStreamParser.GB2312_SUBSET) {
DecodedBitStreamParser.decodeHanziSegment(bits, result, countHanzi);
}
break;
default:
// "Normal" QR code modes:
// How many characters will follow, encoded in this mode?
const count = bits.readBits(mode.getCharacterCountBits(version));
switch (mode) {
case Mode.NUMERIC:
DecodedBitStreamParser.decodeNumericSegment(bits, result, count);
break;
case Mode.ALPHANUMERIC:
DecodedBitStreamParser.decodeAlphanumericSegment(bits, result, count, fc1InEffect);
break;
case Mode.BYTE:
DecodedBitStreamParser.decodeByteSegment(bits, result, count, currentCharacterSetECI, byteSegments, hints);
break;
case Mode.KANJI:
DecodedBitStreamParser.decodeKanjiSegment(bits, result, count);
break;
default:
throw new FormatException();
}
break;
}
} while (mode !== Mode.TERMINATOR);
} catch (iae/*: IllegalArgumentException*/) {
// from readBits() calls
throw new FormatException();
}
return new DecoderResult(bytes,
result.toString(),
byteSegments.length === 0 ? null : byteSegments,
ecLevel === null ? null : ecLevel.toString(),
symbolSequence,
parityData);
}
/**
* See specification GBT 18284-2000
*/
private static decodeHanziSegment(bits: BitSource,
result: StringBuilder,
count: number /*int*/): void /*throws FormatException*/ {
// Don't crash trying to read more bits than we have available.
if (count * 13 > bits.available()) {
throw new FormatException();
}
// Each character will require 2 bytes. Read the characters as 2-byte pairs
// and decode as GB2312 afterwards
const buffer = new Uint8Array(2 * count);
let offset = 0;
while (count > 0) {
// Each 13 bits encodes a 2-byte character
const twoBytes = bits.readBits(13);
let assembledTwoBytes = (((twoBytes / 0x060) << 8) & 0xFFFFFFFF) | (twoBytes % 0x060);
if (assembledTwoBytes < 0x003BF) {
// In the 0xA1A1 to 0xAAFE range
assembledTwoBytes += 0x0A1A1;
} else {
// In the 0xB0A1 to 0xFAFE range
assembledTwoBytes += 0x0A6A1;
}
buffer[offset] = /*(byte) */((assembledTwoBytes >> 8) & 0xFF);
buffer[offset + 1] = /*(byte) */(assembledTwoBytes & 0xFF);
offset += 2;
count--;
}
try {
result.append(StringEncoding.decode(buffer, StringUtils.GB2312));
// TYPESCRIPTPORT: TODO: implement GB2312 decode. StringView from MDN could be a starting point
} catch (ignored/*: UnsupportedEncodingException*/) {
throw new FormatException(ignored);
}
}
private static decodeKanjiSegment(bits: BitSource,
result: StringBuilder,
count: number /*int*/): void /*throws FormatException*/ {
// Don't crash trying to read more bits than we have available.
if (count * 13 > bits.available()) {
throw new FormatException();
}
// Each character will require 2 bytes. Read the characters as 2-byte pairs
// and decode as Shift_JIS afterwards
const buffer = new Uint8Array(2 * count);
let offset = 0;
while (count > 0) {
// Each 13 bits encodes a 2-byte character
const twoBytes = bits.readBits(13);
let assembledTwoBytes = (((twoBytes / 0x0C0) << 8) & 0xFFFFFFFF) | (twoBytes % 0x0C0);
if (assembledTwoBytes < 0x01F00) {
// In the 0x8140 to 0x9FFC range
assembledTwoBytes += 0x08140;
} else {
// In the 0xE040 to 0xEBBF range
assembledTwoBytes += 0x0C140;
}
buffer[offset] = /*(byte) */(assembledTwoBytes >> 8);
buffer[offset + 1] = /*(byte) */assembledTwoBytes;
offset += 2;
count--;
}
// Shift_JIS may not be supported in some environments:
try {
result.append(StringEncoding.decode(buffer, StringUtils.SHIFT_JIS));
// TYPESCRIPTPORT: TODO: implement SHIFT_JIS decode. StringView from MDN could be a starting point
} catch (ignored/*: UnsupportedEncodingException*/) {
throw new FormatException(ignored);
}
}
private static decodeByteSegment(bits: BitSource,
result: StringBuilder,
count: number /*int*/,
currentCharacterSetECI: CharacterSetECI,
byteSegments: Uint8Array[],
hints: Map<DecodeHintType, any>): void /*throws FormatException*/ {
// Don't crash trying to read more bits than we have available.
if (8 * count > bits.available()) {
throw new FormatException();
}
const readBytes = new Uint8Array(count);
for (let i = 0; i < count; i++) {
readBytes[i] = /*(byte) */bits.readBits(8);
}
let encoding: string;
if (currentCharacterSetECI === null) {
// The spec isn't clear on this mode; see
// section 6.4.5: t does not say which encoding to assuming
// upon decoding. I have seen ISO-8859-1 used as well as
// Shift_JIS -- without anything like an ECI designator to
// give a hint.
encoding = StringUtils.guessEncoding(readBytes, hints);
} else {
encoding = currentCharacterSetECI.getName();
}
try {
result.append(StringEncoding.decode(readBytes, encoding));
} catch (ignored/*: UnsupportedEncodingException*/) {
throw new FormatException(ignored);
}
byteSegments.push(readBytes);
}
private static toAlphaNumericChar(value: number /*int*/): string /*throws FormatException*/ {
if (value >= DecodedBitStreamParser.ALPHANUMERIC_CHARS.length) {
throw new FormatException();
}
return DecodedBitStreamParser.ALPHANUMERIC_CHARS[value];
}
private static decodeAlphanumericSegment(bits: BitSource,
result: StringBuilder,
count: number /*int*/,
fc1InEffect: boolean): void /*throws FormatException*/ {
// Read two characters at a time
const start = result.length();
while (count > 1) {
if (bits.available() < 11) {
throw new FormatException();
}
const nextTwoCharsBits = bits.readBits(11);
result.append(DecodedBitStreamParser.toAlphaNumericChar(Math.floor(nextTwoCharsBits / 45)));
result.append(DecodedBitStreamParser.toAlphaNumericChar(nextTwoCharsBits % 45));
count -= 2;
}
if (count === 1) {
// special case: one character left
if (bits.available() < 6) {
throw new FormatException();
}
result.append(DecodedBitStreamParser.toAlphaNumericChar(bits.readBits(6)));
}
// See section 6.4.8.1, 6.4.8.2
if (fc1InEffect) {
// We need to massage the result a bit if in an FNC1 mode:
for (let i = start; i < result.length(); i++) {
if (result.charAt(i) === '%') {
if (i < result.length() - 1 && result.charAt(i + 1) === '%') {
// %% is rendered as %
result.deleteCharAt(i + 1);
} else {
// In alpha mode, % should be converted to FNC1 separator 0x1D
result.setCharAt(i, String.fromCharCode(0x1D));
}
}
}
}
}
private static decodeNumericSegment(bits: BitSource,
result: StringBuilder,
count: number /*int*/): void /*throws FormatException*/ {
// Read three digits at a time
while (count >= 3) {
// Each 10 bits encodes three digits
if (bits.available() < 10) {
throw new FormatException();
}
const threeDigitsBits = bits.readBits(10);
if (threeDigitsBits >= 1000) {
throw new FormatException();
}
result.append(DecodedBitStreamParser.toAlphaNumericChar(Math.floor(threeDigitsBits / 100)));
result.append(DecodedBitStreamParser.toAlphaNumericChar(Math.floor(threeDigitsBits / 10) % 10));
result.append(DecodedBitStreamParser.toAlphaNumericChar(threeDigitsBits % 10));
count -= 3;
}
if (count === 2) {
// Two digits left over to read, encoded in 7 bits
if (bits.available() < 7) {
throw new FormatException();
}
const twoDigitsBits = bits.readBits(7);
if (twoDigitsBits >= 100) {
throw new FormatException();
}
result.append(DecodedBitStreamParser.toAlphaNumericChar(Math.floor(twoDigitsBits / 10)));
result.append(DecodedBitStreamParser.toAlphaNumericChar(twoDigitsBits % 10));
} else if (count === 1) {
// One digit left over to read
if (bits.available() < 4) {
throw new FormatException();
}
const digitBits = bits.readBits(4);
if (digitBits >= 10) {
throw new FormatException();
}
result.append(DecodedBitStreamParser.toAlphaNumericChar(digitBits));
}
}
private static parseECIValue(bits: BitSource): number /*int*/ /*throws FormatException*/ {
const firstByte = bits.readBits(8);
if ((firstByte & 0x80) === 0) {
// just one byte
return firstByte & 0x7F;
}
if ((firstByte & 0xC0) === 0x80) {
// two bytes
const secondByte = bits.readBits(8);
return (((firstByte & 0x3F) << 8) & 0xFFFFFFFF) | secondByte;
}
if ((firstByte & 0xE0) === 0xC0) {
// three bytes
const secondThirdBytes = bits.readBits(16);
return (((firstByte & 0x1F) << 16) & 0xFFFFFFFF) | secondThirdBytes;
}
throw new FormatException();
}
}
// function Uint8ArrayToString(a: Uint8Array): string {
// const CHUNK_SZ = 0x8000;
// const c = new StringBuilder();
// for (let i = 0, length = a.length; i < length; i += CHUNK_SZ) {
// c.append(String.fromCharCode.apply(null, a.subarray(i, i + CHUNK_SZ)));
// }
// return c.toString();
// }