/*
- * Copyright 2007 Google Inc.
+ * 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.
package com.google.zxing.qrcode.decoder;
import com.google.zxing.ReaderException;
+import com.google.zxing.common.BitSource;
+import com.google.zxing.common.CharacterSetECI;
+import com.google.zxing.common.DecoderResult;
import java.io.UnsupportedEncodingException;
+import java.util.Vector;
/**
* <p>QR Codes can encode text as bits in one of several modes, and can use multiple modes
*
* <p>See ISO 18004:2006, 6.4.3 - 6.4.7</p>
*
- * @author srowen@google.com (Sean Owen)
+ * @author Sean Owen
*/
final class DecodedBitStreamParser {
/**
* See ISO 18004:2006, 6.4.4 Table 5
*/
- private static final char[] ALPHANUMERIC_CHARS = new char[]{
+ private static final char[] ALPHANUMERIC_CHARS = {
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B',
'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N',
'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
' ', '$', '%', '*', '+', '-', '.', '/', ':'
};
- private static final String SHIFT_JIS = "Shift_JIS";
+ private static final String SHIFT_JIS = "SJIS";
+ private static final String EUC_JP = "EUC_JP";
private static final boolean ASSUME_SHIFT_JIS;
- private static final String UTF8 = "UTF-8";
- private static final String ISO88591 = "ISO-8859-1";
+ private static final String UTF8 = "UTF8";
+ private static final String ISO88591 = "ISO8859_1";
static {
String platformDefault = System.getProperty("file.encoding");
- ASSUME_SHIFT_JIS = SHIFT_JIS.equalsIgnoreCase(platformDefault) ||
- "EUC-JP".equalsIgnoreCase(platformDefault);
+ ASSUME_SHIFT_JIS = SHIFT_JIS.equalsIgnoreCase(platformDefault) || EUC_JP.equalsIgnoreCase(platformDefault);
}
private DecodedBitStreamParser() {
}
- static String decode(byte[] bytes, Version version) throws ReaderException {
+ static DecoderResult decode(byte[] bytes, Version version) throws ReaderException {
BitSource bits = new BitSource(bytes);
StringBuffer result = new StringBuffer();
+ CharacterSetECI currentCharacterSetECI = null;
+ boolean fc1InEffect = false;
+ Vector byteSegments = new Vector(1);
Mode mode;
do {
// While still another segment to read...
- mode = Mode.forBits(bits.readBits(4)); // mode is encoded by 4 bits
+ if (bits.available() < 4) {
+ // OK, assume we're done. Really, a TERMINATOR mode should have been recorded here
+ mode = Mode.TERMINATOR;
+ } else {
+ mode = Mode.forBits(bits.readBits(4)); // mode is encoded by 4 bits
+ }
if (!mode.equals(Mode.TERMINATOR)) {
- // How many characters will follow, encoded in this mode?
- int count = bits.readBits(mode.getCharacterCountBits(version));
- if (mode.equals(Mode.NUMERIC)) {
- decodeNumericSegment(bits, result, count);
- } else if (mode.equals(Mode.ALPHANUMERIC)) {
- decodeAlphanumericSegment(bits, result, count);
- } else if (mode.equals(Mode.BYTE)) {
- decodeByteSegment(bits, result, count);
- } else if (mode.equals(Mode.KANJI)) {
- decodeKanjiSegment(bits, result, count);
+ if (mode.equals(Mode.FNC1_FIRST_POSITION) || mode.equals(Mode.FNC1_SECOND_POSITION)) {
+ // We do little with FNC1 except alter the parsed result a bit according to the spec
+ fc1InEffect = true;
+ } else if (mode.equals(Mode.ECI)) {
+ // Count doesn't apply to ECI
+ int value = parseECIValue(bits);
+ try {
+ currentCharacterSetECI = CharacterSetECI.getCharacterSetECIByValue(value);
+ } catch (IllegalArgumentException iae) {
+ // unsupported... just continue?
+ }
} else {
- throw new ReaderException("Unsupported mode indicator");
+ // How many characters will follow, encoded in this mode?
+ int count = bits.readBits(mode.getCharacterCountBits(version));
+ if (mode.equals(Mode.NUMERIC)) {
+ decodeNumericSegment(bits, result, count);
+ } else if (mode.equals(Mode.ALPHANUMERIC)) {
+ decodeAlphanumericSegment(bits, result, count, fc1InEffect);
+ } else if (mode.equals(Mode.BYTE)) {
+ decodeByteSegment(bits, result, count, currentCharacterSetECI, byteSegments);
+ } else if (mode.equals(Mode.KANJI)) {
+ decodeKanjiSegment(bits, result, count);
+ } else {
+ throw new ReaderException("Unsupported mode indicator");
+ }
}
}
} while (!mode.equals(Mode.TERMINATOR));
- // I thought it wasn't allowed to leave extra bytes after the terminator but it happens
- /*
- int bitsLeft = bits.available();
- if (bitsLeft > 0) {
- if (bitsLeft > 6 || bits.readBits(bitsLeft) != 0) {
- throw new ReaderException("Excess bits or non-zero bits after terminator mode indicator");
- }
- }
- */
- return result.toString();
+ return new DecoderResult(bytes, result.toString(), byteSegments.isEmpty() ? null : byteSegments);
}
private static void decodeKanjiSegment(BitSource bits,
private static void decodeByteSegment(BitSource bits,
StringBuffer result,
- int count) throws ReaderException {
+ int count,
+ CharacterSetECI currentCharacterSetECI,
+ Vector byteSegments) throws ReaderException {
byte[] readBytes = new byte[count];
if (count << 3 > bits.available()) {
throw new ReaderException("Count too large: " + count);
for (int i = 0; i < count; i++) {
readBytes[i] = (byte) bits.readBits(8);
}
+ String encoding;
+ 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.
- String encoding = guessEncoding(readBytes);
+ encoding = guessEncoding(readBytes);
+ } else {
+ encoding = currentCharacterSetECI.getEncodingName();
+ }
try {
result.append(new String(readBytes, encoding));
} catch (UnsupportedEncodingException uce) {
throw new ReaderException(uce.toString());
}
+ byteSegments.addElement(readBytes);
}
private static void decodeAlphanumericSegment(BitSource bits,
StringBuffer result,
- int count) {
+ int count,
+ boolean fc1InEffect) {
// Read two characters at a time
+ int start = result.length();
while (count > 1) {
int nextTwoCharsBits = bits.readBits(11);
result.append(ALPHANUMERIC_CHARS[nextTwoCharsBits / 45]);
// special case: one character left
result.append(ALPHANUMERIC_CHARS[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 (int 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, (char) 0x1D);
+ }
+ }
+ }
+ }
}
private static void decodeNumericSegment(BitSource bits,
// If we see something else in that second byte, we'll make the risky guess
// that it's UTF-8.
int length = bytes.length;
- for (int i = 0; i < length; i++) {
+ boolean canBeISO88591 = true;
+ boolean canBeShiftJIS = true;
+ boolean sawDoubleByteStart = false;
+ int maybeSingleByteKatakanaCount = 0;
+ boolean lastWasPossibleDoubleByteStart = false;
+ for (int i = 0; i < length && (canBeISO88591 || canBeShiftJIS); i++) {
int value = bytes[i] & 0xFF;
- if (value >= 0x80 && value <= 0x9F && i < length - 1) {
- // ISO-8859-1 shouldn't use this, but before we decide it is Shift_JIS,
- // just double check that it is followed by a byte that's valid in
- // the Shift_JIS encoding
- int nextValue = bytes[i + 1] & 0xFF;
- if ((value & 0x1) == 0) {
- // if even,
- if (nextValue >= 0x9F && nextValue <= 0x7C) {
- return SHIFT_JIS;
- }
+ if (value >= 0x7F && value <= 0x9F) {
+ canBeISO88591 = false;
+ }
+ if (value >= 0xA1 && value <= 0xDF) {
+ // count the number of characters that might be a Shift_JIS single-byte Katakana character
+ if (!lastWasPossibleDoubleByteStart) {
+ maybeSingleByteKatakanaCount++;
+ }
+ }
+ if (!lastWasPossibleDoubleByteStart && ((value >= 0xF0 && value <= 0xFF) || value == 0x80 || value == 0xA0)) {
+ canBeShiftJIS = false;
+ }
+ if (((value >= 0x81 && value <= 0x9F) || (value >= 0xE0 && value <= 0xEF)) && i < length - 1) {
+ // These start double-byte characters in Shift_JIS. Let's see if it's followed by a valid
+ // second byte.
+ sawDoubleByteStart = true;
+ if (lastWasPossibleDoubleByteStart) {
+ // If we just checked this and the last byte for being a valid double-byte
+ // char, don't check starting on this byte. If this and the last byte
+ // formed a valid pair, then this shouldn't be checked to see if it starts
+ // a double byte pair of course.
+ lastWasPossibleDoubleByteStart = false;
} else {
- if (nextValue >= 0x40 && nextValue <= 0x9E) {
- return SHIFT_JIS;
+ // ... otherwise do check to see if this plus the next byte form a valid
+ // double byte pair encoding a character.
+ lastWasPossibleDoubleByteStart = true;
+ int nextValue = bytes[i + 1] & 0xFF;
+ if (nextValue < 0x40 || nextValue > 0xFC) {
+ canBeShiftJIS = false;
}
+ // There is some conflicting information out there about which bytes can follow which in
+ // double-byte Shift_JIS characters. The rule above seems to be the one that matches practice.
}
- // otherwise we're going to take a guess that it's UTF-8
- return UTF8;
+ } else {
+ lastWasPossibleDoubleByteStart = false;
}
}
- return ISO88591;
+ // Distinguishing Shift_JIS and ISO-8859-1 can be a little tough. The crude heuristic is:
+ // - If we saw
+ // - at least one byte that starts a double-byte value (bytes that are rare in ISO-8859-1), or
+ // - over 5% of bytes that could be single-byte Katakana (also rare in ISO-8859-1),
+ // - and, saw no sequences that are invalid in Shift_JIS, then we conclude Shift_JIS
+ if ((sawDoubleByteStart || 20 * maybeSingleByteKatakanaCount > length) && canBeShiftJIS) {
+ return SHIFT_JIS;
+ }
+ // Otherwise, we default to ISO-8859-1 unless we know it can't be
+ if (canBeISO88591) {
+ return ISO88591;
+ }
+ // Otherwise, we take a wild guess with UTF-8
+ return UTF8;
+ }
+
+ private static int parseECIValue(BitSource bits) {
+ int firstByte = bits.readBits(8);
+ if ((firstByte & 0x80) == 0) {
+ // just one byte
+ return firstByte & 0x7F;
+ } else if ((firstByte & 0xC0) == 0x80) {
+ // two bytes
+ int secondByte = bits.readBits(8);
+ return ((firstByte & 0x3F) << 8) | secondByte;
+ } else if ((firstByte & 0xE0) == 0xC0) {
+ // three bytes
+ int secondThirdBytes = bits.readBits(16);
+ return ((firstByte & 0x1F) << 16) | secondThirdBytes;
+ }
+ throw new IllegalArgumentException("Bad ECI bits starting with byte " + firstByte);
}
}
projects / zxing.git / blobdiff