// Embed type information. On success, modify the matrix. public static void embedTypeInfo(ErrorCorrectionLevel ecLevel, int maskPattern, ByteMatrix matrix) throws WriterException { BitArray typeInfoBits = new BitArray(); makeTypeInfoBits(ecLevel, maskPattern, typeInfoBits); for (int i = 0; i < typeInfoBits.getSize(); ++i) { // Place bits in LSB to MSB order. LSB (least significant bit) is the last value in // "typeInfoBits". boolean bit = typeInfoBits.get(typeInfoBits.getSize() - 1 - i); // Type info bits at the left top corner. See 8.9 of JISX0510:2004 (p.46). int x1 = TYPE_INFO_COORDINATES[i][0]; int y1 = TYPE_INFO_COORDINATES[i][1]; matrix.set(x1, y1, bit); if (i < 8) { // Right top corner. int x2 = matrix.getWidth() - i - 1; int y2 = 8; matrix.set(x2, y2, bit); } else { // Left bottom corner. int x2 = 8; int y2 = matrix.getHeight() - 7 + (i - 8); matrix.set(x2, y2, bit); } } }
// Make bit vector of version information. On success, store the result in "bits" and return true. // See 8.10 of JISX0510:2004 (p.45) for details. public static void makeVersionInfoBits(int version, BitArray bits) throws WriterException { bits.appendBits(version, 6); int bchCode = calculateBCHCode(version, VERSION_INFO_POLY); bits.appendBits(bchCode, 12); if (bits.getSize() != 18) { // Just in case. throw new WriterException("should not happen but we got: " + bits.getSize()); } }
// Embed "dataBits" using "getMaskPattern". On success, modify the matrix and return true. // For debugging purposes, it skips masking process if "getMaskPattern" is -1. // See 8.7 of JISX0510:2004 (p.38) for how to embed data bits. public static void embedDataBits(BitArray dataBits, int maskPattern, ByteMatrix matrix) throws WriterException { int bitIndex = 0; int direction = -1; // Start from the right bottom cell. int x = matrix.getWidth() - 1; int y = matrix.getHeight() - 1; while (x > 0) { // Skip the vertical timing pattern. if (x == 6) { x -= 1; } while (y >= 0 && y < matrix.getHeight()) { for (int i = 0; i < 2; ++i) { int xx = x - i; // Skip the cell if it's not empty. if (!isEmpty(matrix.get(xx, y))) { continue; } boolean bit; if (bitIndex < dataBits.getSize()) { bit = dataBits.get(bitIndex); ++bitIndex; } else { // Padding bit. If there is no bit left, we'll fill the left cells with 0, as described // in 8.4.9 of JISX0510:2004 (p. 24). bit = false; } // Skip masking if mask_pattern is -1. if (maskPattern != -1) { if (MaskUtil.getDataMaskBit(maskPattern, xx, y)) { bit = !bit; } } matrix.set(xx, y, bit); } y += direction; } direction = -direction; // Reverse the direction. y += direction; x -= 2; // Move to the left. } // All bits should be consumed. if (bitIndex != dataBits.getSize()) { throw new WriterException("Not all bits consumed: " + bitIndex + '/' + dataBits.getSize()); } }
// Embed version information if need be. On success, modify the matrix and return true. // See 8.10 of JISX0510:2004 (p.47) for how to embed version information. public static void maybeEmbedVersionInfo(int version, ByteMatrix matrix) throws WriterException { if (version < 7) { // Version info is necessary if version >= 7. return; // Don't need version info. } BitArray versionInfoBits = new BitArray(); makeVersionInfoBits(version, versionInfoBits); int bitIndex = 6 * 3 - 1; // It will decrease from 17 to 0. for (int i = 0; i < 6; ++i) { for (int j = 0; j < 3; ++j) { // Place bits in LSB (least significant bit) to MSB order. boolean bit = versionInfoBits.get(bitIndex); bitIndex--; // Left bottom corner. matrix.set(i, matrix.getHeight() - 11 + j, bit); // Right bottom corner. matrix.set(matrix.getHeight() - 11 + j, i, bit); } } }
// Make bit vector of type information. On success, store the result in "bits" and return true. // Encode error correction level and mask pattern. See 8.9 of // JISX0510:2004 (p.45) for details. public static void makeTypeInfoBits(ErrorCorrectionLevel ecLevel, int maskPattern, BitArray bits) throws WriterException { if (!QRCode.isValidMaskPattern(maskPattern)) { throw new WriterException("Invalid mask pattern"); } int typeInfo = (ecLevel.getBits() << 3) | maskPattern; bits.appendBits(typeInfo, 5); int bchCode = calculateBCHCode(typeInfo, TYPE_INFO_POLY); bits.appendBits(bchCode, 10); BitArray maskBits = new BitArray(); maskBits.appendBits(TYPE_INFO_MASK_PATTERN, 15); bits.xor(maskBits); if (bits.getSize() != 15) { // Just in case. throw new WriterException("should not happen but we got: " + bits.getSize()); } }