diff options
Diffstat (limited to 'libraries/zxing/src/com/google/zxing/qrcode/encoder/Encoder.java')
| -rw-r--r-- | libraries/zxing/src/com/google/zxing/qrcode/encoder/Encoder.java | 557 |
1 files changed, 557 insertions, 0 deletions
diff --git a/libraries/zxing/src/com/google/zxing/qrcode/encoder/Encoder.java b/libraries/zxing/src/com/google/zxing/qrcode/encoder/Encoder.java new file mode 100644 index 000000000..8796511ab --- /dev/null +++ b/libraries/zxing/src/com/google/zxing/qrcode/encoder/Encoder.java @@ -0,0 +1,557 @@ +/* + * 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.ECI; +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.Hashtable; +import java.util.Vector; + +/** + * @author satorux@google.com (Satoru Takabayashi) - creator + * @author dswitkin@google.com (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) { + int penalty = 0; + penalty += MaskUtil.applyMaskPenaltyRule1(matrix); + penalty += MaskUtil.applyMaskPenaltyRule2(matrix); + penalty += MaskUtil.applyMaskPenaltyRule3(matrix); + penalty += MaskUtil.applyMaskPenaltyRule4(matrix); + return penalty; + } + + /** + * 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 void encode(String content, ErrorCorrectionLevel ecLevel, QRCode qrCode) + throws WriterException { + encode(content, ecLevel, null, qrCode); + } + + public static void encode(String content, ErrorCorrectionLevel ecLevel, Hashtable hints, + QRCode qrCode) throws WriterException { + + String encoding = hints == null ? null : (String) hints.get(EncodeHintType.CHARACTER_SET); + if (encoding == null) { + encoding = DEFAULT_BYTE_MODE_ENCODING; + } + + // Step 1: Choose the mode (encoding). + Mode mode = chooseMode(content, encoding); + + // Step 2: Append "bytes" into "dataBits" in appropriate encoding. + BitArray dataBits = new BitArray(); + appendBytes(content, mode, dataBits, encoding); + // Step 3: Initialize QR code that can contain "dataBits". + int numInputBytes = dataBits.getSizeInBytes(); + initQRCode(numInputBytes, ecLevel, mode, qrCode); + + // Step 4: Build another bit vector that contains header and data. + BitArray headerAndDataBits = new BitArray(); + + // Step 4.5: Append ECI message if applicable + if (mode == Mode.BYTE && !DEFAULT_BYTE_MODE_ENCODING.equals(encoding)) { + CharacterSetECI eci = CharacterSetECI.getCharacterSetECIByName(encoding); + if (eci != null) { + appendECI(eci, headerAndDataBits); + } + } + + appendModeInfo(mode, headerAndDataBits); + + int numLetters = mode.equals(Mode.BYTE) ? dataBits.getSizeInBytes() : content.length(); + appendLengthInfo(numLetters, qrCode.getVersion(), mode, headerAndDataBits); + headerAndDataBits.appendBitArray(dataBits); + + // Step 5: Terminate the bits properly. + terminateBits(qrCode.getNumDataBytes(), headerAndDataBits); + + // Step 6: Interleave data bits with error correction code. + BitArray finalBits = new BitArray(); + interleaveWithECBytes(headerAndDataBits, qrCode.getNumTotalBytes(), qrCode.getNumDataBytes(), + qrCode.getNumRSBlocks(), finalBits); + + // Step 7: Choose the mask pattern and set to "qrCode". + ByteMatrix matrix = new ByteMatrix(qrCode.getMatrixWidth(), qrCode.getMatrixWidth()); + qrCode.setMaskPattern(chooseMaskPattern(finalBits, qrCode.getECLevel(), qrCode.getVersion(), + matrix)); + + // Step 8. Build the matrix and set it to "qrCode". + MatrixUtil.buildMatrix(finalBits, qrCode.getECLevel(), qrCode.getVersion(), + qrCode.getMaskPattern(), matrix); + qrCode.setMatrix(matrix); + // Step 9. Make sure we have a valid QR Code. + if (!qrCode.isValid()) { + throw new WriterException("Invalid QR code: " + qrCode.toString()); + } + } + + /** + * @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}. + */ + public 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; + } else if (hasNumeric) { + return Mode.NUMERIC; + } + return Mode.BYTE; + } + + private static boolean isOnlyDoubleByteKanji(String content) { + byte[] bytes; + try { + bytes = content.getBytes("Shift_JIS"); + } catch (UnsupportedEncodingException uee) { + 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, int 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; + } + + /** + * Initialize "qrCode" according to "numInputBytes", "ecLevel", and "mode". On success, + * modify "qrCode". + */ + private static void initQRCode(int numInputBytes, ErrorCorrectionLevel ecLevel, Mode mode, + QRCode qrCode) throws WriterException { + qrCode.setECLevel(ecLevel); + qrCode.setMode(mode); + + // 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(); + // getNumRSBlocks = 5 + int numRSBlocks = ecBlocks.getNumBlocks(); + // getNumDataBytes = 196 - 130 = 66 + int numDataBytes = numBytes - numEcBytes; + // We want to choose the smallest version which can contain data of "numInputBytes" + some + // extra bits for the header (mode info and length info). The header can be three bytes + // (precisely 4 + 16 bits) at most. Hence we do +3 here. + if (numDataBytes >= numInputBytes + 3) { + // Yay, we found the proper rs block info! + qrCode.setVersion(versionNum); + qrCode.setNumTotalBytes(numBytes); + qrCode.setNumDataBytes(numDataBytes); + qrCode.setNumRSBlocks(numRSBlocks); + // getNumECBytes = 196 - 66 = 130 + qrCode.setNumECBytes(numEcBytes); + // matrix width = 21 + 6 * 4 = 45 + qrCode.setMatrixWidth(version.getDimensionForVersion()); + return; + } + } + throw new WriterException("Cannot find proper rs block info (input 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 void interleaveWithECBytes(BitArray bits, int numTotalBytes, + int numDataBytes, int numRSBlocks, BitArray result) 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. + Vector blocks = new Vector(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.addElement(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"); + } + + // First, place data blocks. + for (int i = 0; i < maxNumDataBytes; ++i) { + for (int j = 0; j < blocks.size(); ++j) { + byte[] dataBytes = ((BlockPair) blocks.elementAt(j)).getDataBytes(); + if (i < dataBytes.length) { + result.appendBits(dataBytes[i], 8); + } + } + } + // Then, place error correction blocks. + for (int i = 0; i < maxNumEcBytes; ++i) { + for (int j = 0; j < blocks.size(); ++j) { + byte[] ecBytes = ((BlockPair) blocks.elementAt(j)).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."); + } + } + + 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, int version, Mode mode, BitArray bits) + throws WriterException { + int numBits = mode.getCharacterCountBits(Version.getVersionForNumber(version)); + if (numLetters > ((1 << numBits) - 1)) { + 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 { + if (mode.equals(Mode.NUMERIC)) { + appendNumericBytes(content, bits); + } else if (mode.equals(Mode.ALPHANUMERIC)) { + appendAlphanumericBytes(content, bits); + } else if (mode.equals(Mode.BYTE)) { + append8BitBytes(content, bits, encoding); + } else if (mode.equals(Mode.KANJI)) { + appendKanjiBytes(content, bits); + } else { + throw new WriterException("Invalid mode: " + mode); + } + } + + static void appendNumericBytes(String 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(String 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.toString()); + } + for (int i = 0; i < bytes.length; ++i) { + bits.appendBits(bytes[i], 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.toString()); + } + 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(ECI 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); + } + +} |