com.google.zxing.qrcode.encoder.Encoder Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of core Show documentation
Show all versions of core Show documentation
Core barcode encoding/decoding library
/*
* Copyright 2008 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.
*/
package com.google.zxing.qrcode.encoder;
import com.google.zxing.EncodeHintType;
import com.google.zxing.WriterException;
import com.google.zxing.common.BitArray;
import com.google.zxing.common.CharacterSetECI;
import com.google.zxing.common.reedsolomon.GenericGF;
import com.google.zxing.common.reedsolomon.ReedSolomonEncoder;
import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel;
import com.google.zxing.qrcode.decoder.Mode;
import com.google.zxing.qrcode.decoder.Version;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Map;
/**
* @author [email protected] (Satoru Takabayashi) - creator
* @author [email protected] (Daniel Switkin) - ported from C++
*/
public final class Encoder {
// The original table is defined in the table 5 of JISX0510:2004 (p.19).
private static final int[] ALPHANUMERIC_TABLE = {
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 0x00-0x0f
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 0x10-0x1f
36, -1, -1, -1, 37, 38, -1, -1, -1, -1, 39, 40, -1, 41, 42, 43, // 0x20-0x2f
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 44, -1, -1, -1, -1, -1, // 0x30-0x3f
-1, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, // 0x40-0x4f
25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, -1, -1, -1, -1, -1, // 0x50-0x5f
};
static final String DEFAULT_BYTE_MODE_ENCODING = "ISO-8859-1";
private Encoder() {
}
// The mask penalty calculation is complicated. See Table 21 of JISX0510:2004 (p.45) for details.
// Basically it applies four rules and summate all penalties.
private static int calculateMaskPenalty(ByteMatrix matrix) {
return MaskUtil.applyMaskPenaltyRule1(matrix)
+ MaskUtil.applyMaskPenaltyRule2(matrix)
+ MaskUtil.applyMaskPenaltyRule3(matrix)
+ MaskUtil.applyMaskPenaltyRule4(matrix);
}
/**
* Encode "bytes" with the error correction level "ecLevel". The encoding mode will be chosen
* internally by chooseMode(). On success, store the result in "qrCode".
*
* We recommend you to use QRCode.EC_LEVEL_L (the lowest level) for
* "getECLevel" since our primary use is to show QR code on desktop screens. We don't need very
* strong error correction for this purpose.
*
* Note that there is no way to encode bytes in MODE_KANJI. We might want to add EncodeWithMode()
* with which clients can specify the encoding mode. For now, we don't need the functionality.
*/
public static QRCode encode(String content, ErrorCorrectionLevel ecLevel) throws WriterException {
return encode(content, ecLevel, null);
}
public static QRCode encode(String content,
ErrorCorrectionLevel ecLevel,
Map hints) throws WriterException {
// Determine what character encoding has been specified by the caller, if any
String encoding = hints == null ? null : (String) hints.get(EncodeHintType.CHARACTER_SET);
if (encoding == null) {
encoding = DEFAULT_BYTE_MODE_ENCODING;
}
// Pick an encoding mode appropriate for the content. Note that this will not attempt to use
// multiple modes / segments even if that were more efficient. Twould be nice.
Mode mode = chooseMode(content, encoding);
// This will store the header information, like mode and
// length, as well as "header" segments like an ECI segment.
BitArray headerBits = new BitArray();
// Append ECI segment if applicable
if (mode == Mode.BYTE && !DEFAULT_BYTE_MODE_ENCODING.equals(encoding)) {
CharacterSetECI eci = CharacterSetECI.getCharacterSetECIByName(encoding);
if (eci != null) {
appendECI(eci, headerBits);
}
}
// (With ECI in place,) Write the mode marker
appendModeInfo(mode, headerBits);
// Collect data within the main segment, separately, to count its size if needed. Don't add it to
// main payload yet.
BitArray dataBits = new BitArray();
appendBytes(content, mode, dataBits, encoding);
// Hard part: need to know version to know how many bits length takes. But need to know how many
// bits it takes to know version. First we take a guess at version by assuming version will be
// the minimum, 1:
int provisionalBitsNeeded = headerBits.getSize()
+ mode.getCharacterCountBits(Version.getVersionForNumber(1))
+ dataBits.getSize();
Version provisionalVersion = chooseVersion(provisionalBitsNeeded, ecLevel);
// Use that guess to calculate the right version. I am still not sure this works in 100% of cases.
int bitsNeeded = headerBits.getSize()
+ mode.getCharacterCountBits(provisionalVersion)
+ dataBits.getSize();
Version version = chooseVersion(bitsNeeded, ecLevel);
BitArray headerAndDataBits = new BitArray();
headerAndDataBits.appendBitArray(headerBits);
// Find "length" of main segment and write it
int numLetters = mode == Mode.BYTE ? dataBits.getSizeInBytes() : content.length();
appendLengthInfo(numLetters, version, mode, headerAndDataBits);
// Put data together into the overall payload
headerAndDataBits.appendBitArray(dataBits);
Version.ECBlocks ecBlocks = version.getECBlocksForLevel(ecLevel);
int numDataBytes = version.getTotalCodewords() - ecBlocks.getTotalECCodewords();
// Terminate the bits properly.
terminateBits(numDataBytes, headerAndDataBits);
// Interleave data bits with error correction code.
BitArray finalBits = interleaveWithECBytes(headerAndDataBits,
version.getTotalCodewords(),
numDataBytes,
ecBlocks.getNumBlocks());
QRCode qrCode = new QRCode();
qrCode.setECLevel(ecLevel);
qrCode.setMode(mode);
qrCode.setVersion(version);
// Choose the mask pattern and set to "qrCode".
int dimension = version.getDimensionForVersion();
ByteMatrix matrix = new ByteMatrix(dimension, dimension);
int maskPattern = chooseMaskPattern(finalBits, ecLevel, version, matrix);
qrCode.setMaskPattern(maskPattern);
// Build the matrix and set it to "qrCode".
MatrixUtil.buildMatrix(finalBits, ecLevel, version, maskPattern, matrix);
qrCode.setMatrix(matrix);
return qrCode;
}
/**
* @return the code point of the table used in alphanumeric mode or
* -1 if there is no corresponding code in the table.
*/
static int getAlphanumericCode(int code) {
if (code < ALPHANUMERIC_TABLE.length) {
return ALPHANUMERIC_TABLE[code];
}
return -1;
}
public static Mode chooseMode(String content) {
return chooseMode(content, null);
}
/**
* Choose the best mode by examining the content. Note that 'encoding' is used as a hint;
* if it is Shift_JIS, and the input is only double-byte Kanji, then we return {@link Mode#KANJI}.
*/
private static Mode chooseMode(String content, String encoding) {
if ("Shift_JIS".equals(encoding)) {
// Choose Kanji mode if all input are double-byte characters
return isOnlyDoubleByteKanji(content) ? Mode.KANJI : Mode.BYTE;
}
boolean hasNumeric = false;
boolean hasAlphanumeric = false;
for (int i = 0; i < content.length(); ++i) {
char c = content.charAt(i);
if (c >= '0' && c <= '9') {
hasNumeric = true;
} else if (getAlphanumericCode(c) != -1) {
hasAlphanumeric = true;
} else {
return Mode.BYTE;
}
}
if (hasAlphanumeric) {
return Mode.ALPHANUMERIC;
}
if (hasNumeric) {
return Mode.NUMERIC;
}
return Mode.BYTE;
}
private static boolean isOnlyDoubleByteKanji(String content) {
byte[] bytes;
try {
bytes = content.getBytes("Shift_JIS");
} catch (UnsupportedEncodingException ignored) {
return false;
}
int length = bytes.length;
if (length % 2 != 0) {
return false;
}
for (int i = 0; i < length; i += 2) {
int byte1 = bytes[i] & 0xFF;
if ((byte1 < 0x81 || byte1 > 0x9F) && (byte1 < 0xE0 || byte1 > 0xEB)) {
return false;
}
}
return true;
}
private static int chooseMaskPattern(BitArray bits,
ErrorCorrectionLevel ecLevel,
Version version,
ByteMatrix matrix) throws WriterException {
int minPenalty = Integer.MAX_VALUE; // Lower penalty is better.
int bestMaskPattern = -1;
// We try all mask patterns to choose the best one.
for (int maskPattern = 0; maskPattern < QRCode.NUM_MASK_PATTERNS; maskPattern++) {
MatrixUtil.buildMatrix(bits, ecLevel, version, maskPattern, matrix);
int penalty = calculateMaskPenalty(matrix);
if (penalty < minPenalty) {
minPenalty = penalty;
bestMaskPattern = maskPattern;
}
}
return bestMaskPattern;
}
private static Version chooseVersion(int numInputBits, ErrorCorrectionLevel ecLevel) throws WriterException {
// In the following comments, we use numbers of Version 7-H.
for (int versionNum = 1; versionNum <= 40; versionNum++) {
Version version = Version.getVersionForNumber(versionNum);
// numBytes = 196
int numBytes = version.getTotalCodewords();
// getNumECBytes = 130
Version.ECBlocks ecBlocks = version.getECBlocksForLevel(ecLevel);
int numEcBytes = ecBlocks.getTotalECCodewords();
// getNumDataBytes = 196 - 130 = 66
int numDataBytes = numBytes - numEcBytes;
int totalInputBytes = (numInputBits + 7) / 8;
if (numDataBytes >= totalInputBytes) {
return version;
}
}
throw new WriterException("Data too big");
}
/**
* Terminate bits as described in 8.4.8 and 8.4.9 of JISX0510:2004 (p.24).
*/
static void terminateBits(int numDataBytes, BitArray bits) throws WriterException {
int capacity = numDataBytes << 3;
if (bits.getSize() > capacity) {
throw new WriterException("data bits cannot fit in the QR Code" + bits.getSize() + " > " +
capacity);
}
for (int i = 0; i < 4 && bits.getSize() < capacity; ++i) {
bits.appendBit(false);
}
// Append termination bits. See 8.4.8 of JISX0510:2004 (p.24) for details.
// If the last byte isn't 8-bit aligned, we'll add padding bits.
int numBitsInLastByte = bits.getSize() & 0x07;
if (numBitsInLastByte > 0) {
for (int i = numBitsInLastByte; i < 8; i++) {
bits.appendBit(false);
}
}
// If we have more space, we'll fill the space with padding patterns defined in 8.4.9 (p.24).
int numPaddingBytes = numDataBytes - bits.getSizeInBytes();
for (int i = 0; i < numPaddingBytes; ++i) {
bits.appendBits((i & 0x01) == 0 ? 0xEC : 0x11, 8);
}
if (bits.getSize() != capacity) {
throw new WriterException("Bits size does not equal capacity");
}
}
/**
* Get number of data bytes and number of error correction bytes for block id "blockID". Store
* the result in "numDataBytesInBlock", and "numECBytesInBlock". See table 12 in 8.5.1 of
* JISX0510:2004 (p.30)
*/
static void getNumDataBytesAndNumECBytesForBlockID(int numTotalBytes,
int numDataBytes,
int numRSBlocks,
int blockID,
int[] numDataBytesInBlock,
int[] numECBytesInBlock) throws WriterException {
if (blockID >= numRSBlocks) {
throw new WriterException("Block ID too large");
}
// numRsBlocksInGroup2 = 196 % 5 = 1
int numRsBlocksInGroup2 = numTotalBytes % numRSBlocks;
// numRsBlocksInGroup1 = 5 - 1 = 4
int numRsBlocksInGroup1 = numRSBlocks - numRsBlocksInGroup2;
// numTotalBytesInGroup1 = 196 / 5 = 39
int numTotalBytesInGroup1 = numTotalBytes / numRSBlocks;
// numTotalBytesInGroup2 = 39 + 1 = 40
int numTotalBytesInGroup2 = numTotalBytesInGroup1 + 1;
// numDataBytesInGroup1 = 66 / 5 = 13
int numDataBytesInGroup1 = numDataBytes / numRSBlocks;
// numDataBytesInGroup2 = 13 + 1 = 14
int numDataBytesInGroup2 = numDataBytesInGroup1 + 1;
// numEcBytesInGroup1 = 39 - 13 = 26
int numEcBytesInGroup1 = numTotalBytesInGroup1 - numDataBytesInGroup1;
// numEcBytesInGroup2 = 40 - 14 = 26
int numEcBytesInGroup2 = numTotalBytesInGroup2 - numDataBytesInGroup2;
// Sanity checks.
// 26 = 26
if (numEcBytesInGroup1 != numEcBytesInGroup2) {
throw new WriterException("EC bytes mismatch");
}
// 5 = 4 + 1.
if (numRSBlocks != numRsBlocksInGroup1 + numRsBlocksInGroup2) {
throw new WriterException("RS blocks mismatch");
}
// 196 = (13 + 26) * 4 + (14 + 26) * 1
if (numTotalBytes !=
((numDataBytesInGroup1 + numEcBytesInGroup1) *
numRsBlocksInGroup1) +
((numDataBytesInGroup2 + numEcBytesInGroup2) *
numRsBlocksInGroup2)) {
throw new WriterException("Total bytes mismatch");
}
if (blockID < numRsBlocksInGroup1) {
numDataBytesInBlock[0] = numDataBytesInGroup1;
numECBytesInBlock[0] = numEcBytesInGroup1;
} else {
numDataBytesInBlock[0] = numDataBytesInGroup2;
numECBytesInBlock[0] = numEcBytesInGroup2;
}
}
/**
* Interleave "bits" with corresponding error correction bytes. On success, store the result in
* "result". The interleave rule is complicated. See 8.6 of JISX0510:2004 (p.37) for details.
*/
static BitArray interleaveWithECBytes(BitArray bits,
int numTotalBytes,
int numDataBytes,
int numRSBlocks) throws WriterException {
// "bits" must have "getNumDataBytes" bytes of data.
if (bits.getSizeInBytes() != numDataBytes) {
throw new WriterException("Number of bits and data bytes does not match");
}
// Step 1. Divide data bytes into blocks and generate error correction bytes for them. We'll
// store the divided data bytes blocks and error correction bytes blocks into "blocks".
int dataBytesOffset = 0;
int maxNumDataBytes = 0;
int maxNumEcBytes = 0;
// Since, we know the number of reedsolmon blocks, we can initialize the vector with the number.
Collection blocks = new ArrayList(numRSBlocks);
for (int i = 0; i < numRSBlocks; ++i) {
int[] numDataBytesInBlock = new int[1];
int[] numEcBytesInBlock = new int[1];
getNumDataBytesAndNumECBytesForBlockID(
numTotalBytes, numDataBytes, numRSBlocks, i,
numDataBytesInBlock, numEcBytesInBlock);
int size = numDataBytesInBlock[0];
byte[] dataBytes = new byte[size];
bits.toBytes(8*dataBytesOffset, dataBytes, 0, size);
byte[] ecBytes = generateECBytes(dataBytes, numEcBytesInBlock[0]);
blocks.add(new BlockPair(dataBytes, ecBytes));
maxNumDataBytes = Math.max(maxNumDataBytes, size);
maxNumEcBytes = Math.max(maxNumEcBytes, ecBytes.length);
dataBytesOffset += numDataBytesInBlock[0];
}
if (numDataBytes != dataBytesOffset) {
throw new WriterException("Data bytes does not match offset");
}
BitArray result = new BitArray();
// First, place data blocks.
for (int i = 0; i < maxNumDataBytes; ++i) {
for (BlockPair block : blocks) {
byte[] dataBytes = block.getDataBytes();
if (i < dataBytes.length) {
result.appendBits(dataBytes[i], 8);
}
}
}
// Then, place error correction blocks.
for (int i = 0; i < maxNumEcBytes; ++i) {
for (BlockPair block : blocks) {
byte[] ecBytes = block.getErrorCorrectionBytes();
if (i < ecBytes.length) {
result.appendBits(ecBytes[i], 8);
}
}
}
if (numTotalBytes != result.getSizeInBytes()) { // Should be same.
throw new WriterException("Interleaving error: " + numTotalBytes + " and " +
result.getSizeInBytes() + " differ.");
}
return result;
}
static byte[] generateECBytes(byte[] dataBytes, int numEcBytesInBlock) {
int numDataBytes = dataBytes.length;
int[] toEncode = new int[numDataBytes + numEcBytesInBlock];
for (int i = 0; i < numDataBytes; i++) {
toEncode[i] = dataBytes[i] & 0xFF;
}
new ReedSolomonEncoder(GenericGF.QR_CODE_FIELD_256).encode(toEncode, numEcBytesInBlock);
byte[] ecBytes = new byte[numEcBytesInBlock];
for (int i = 0; i < numEcBytesInBlock; i++) {
ecBytes[i] = (byte) toEncode[numDataBytes + i];
}
return ecBytes;
}
/**
* Append mode info. On success, store the result in "bits".
*/
static void appendModeInfo(Mode mode, BitArray bits) {
bits.appendBits(mode.getBits(), 4);
}
/**
* Append length info. On success, store the result in "bits".
*/
static void appendLengthInfo(int numLetters, Version version, Mode mode, BitArray bits) throws WriterException {
int numBits = mode.getCharacterCountBits(version);
if (numLetters >= (1 << numBits)) {
throw new WriterException(numLetters + " is bigger than " + ((1 << numBits) - 1));
}
bits.appendBits(numLetters, numBits);
}
/**
* Append "bytes" in "mode" mode (encoding) into "bits". On success, store the result in "bits".
*/
static void appendBytes(String content,
Mode mode,
BitArray bits,
String encoding) throws WriterException {
switch (mode) {
case NUMERIC:
appendNumericBytes(content, bits);
break;
case ALPHANUMERIC:
appendAlphanumericBytes(content, bits);
break;
case BYTE:
append8BitBytes(content, bits, encoding);
break;
case KANJI:
appendKanjiBytes(content, bits);
break;
default:
throw new WriterException("Invalid mode: " + mode);
}
}
static void appendNumericBytes(CharSequence content, BitArray bits) {
int length = content.length();
int i = 0;
while (i < length) {
int num1 = content.charAt(i) - '0';
if (i + 2 < length) {
// Encode three numeric letters in ten bits.
int num2 = content.charAt(i + 1) - '0';
int num3 = content.charAt(i + 2) - '0';
bits.appendBits(num1 * 100 + num2 * 10 + num3, 10);
i += 3;
} else if (i + 1 < length) {
// Encode two numeric letters in seven bits.
int num2 = content.charAt(i + 1) - '0';
bits.appendBits(num1 * 10 + num2, 7);
i += 2;
} else {
// Encode one numeric letter in four bits.
bits.appendBits(num1, 4);
i++;
}
}
}
static void appendAlphanumericBytes(CharSequence content, BitArray bits) throws WriterException {
int length = content.length();
int i = 0;
while (i < length) {
int code1 = getAlphanumericCode(content.charAt(i));
if (code1 == -1) {
throw new WriterException();
}
if (i + 1 < length) {
int code2 = getAlphanumericCode(content.charAt(i + 1));
if (code2 == -1) {
throw new WriterException();
}
// Encode two alphanumeric letters in 11 bits.
bits.appendBits(code1 * 45 + code2, 11);
i += 2;
} else {
// Encode one alphanumeric letter in six bits.
bits.appendBits(code1, 6);
i++;
}
}
}
static void append8BitBytes(String content, BitArray bits, String encoding)
throws WriterException {
byte[] bytes;
try {
bytes = content.getBytes(encoding);
} catch (UnsupportedEncodingException uee) {
throw new WriterException(uee);
}
for (byte b : bytes) {
bits.appendBits(b, 8);
}
}
static void appendKanjiBytes(String content, BitArray bits) throws WriterException {
byte[] bytes;
try {
bytes = content.getBytes("Shift_JIS");
} catch (UnsupportedEncodingException uee) {
throw new WriterException(uee);
}
int length = bytes.length;
for (int i = 0; i < length; i += 2) {
int byte1 = bytes[i] & 0xFF;
int byte2 = bytes[i + 1] & 0xFF;
int code = (byte1 << 8) | byte2;
int subtracted = -1;
if (code >= 0x8140 && code <= 0x9ffc) {
subtracted = code - 0x8140;
} else if (code >= 0xe040 && code <= 0xebbf) {
subtracted = code - 0xc140;
}
if (subtracted == -1) {
throw new WriterException("Invalid byte sequence");
}
int encoded = ((subtracted >> 8) * 0xc0) + (subtracted & 0xff);
bits.appendBits(encoded, 13);
}
}
private static void appendECI(CharacterSetECI eci, BitArray bits) {
bits.appendBits(Mode.ECI.getBits(), 4);
// This is correct for values up to 127, which is all we need now.
bits.appendBits(eci.getValue(), 8);
}
}
© 2015 - 2024 Weber Informatics LLC | Privacy Policy