diff options
Diffstat (limited to 'libraries/zxing/src/com/google/zxing/qrcode/decoder/BitMatrixParser.java')
| -rw-r--r-- | libraries/zxing/src/com/google/zxing/qrcode/decoder/BitMatrixParser.java | 203 |
1 files changed, 203 insertions, 0 deletions
diff --git a/libraries/zxing/src/com/google/zxing/qrcode/decoder/BitMatrixParser.java b/libraries/zxing/src/com/google/zxing/qrcode/decoder/BitMatrixParser.java new file mode 100644 index 000000000..9d131a554 --- /dev/null +++ b/libraries/zxing/src/com/google/zxing/qrcode/decoder/BitMatrixParser.java @@ -0,0 +1,203 @@ +/*
+ * 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.
+ */
+
+package com.google.zxing.qrcode.decoder;
+
+import com.google.zxing.FormatException;
+import com.google.zxing.common.BitMatrix;
+
+/**
+ * @author Sean Owen
+ */
+final class BitMatrixParser {
+
+ private final BitMatrix bitMatrix;
+ private Version parsedVersion;
+ private FormatInformation parsedFormatInfo;
+
+ /**
+ * @param bitMatrix {@link BitMatrix} to parse
+ * @throws FormatException if dimension is not >= 21 and 1 mod 4
+ */
+ BitMatrixParser(BitMatrix bitMatrix) throws FormatException {
+ int dimension = bitMatrix.getHeight();
+ if (dimension < 21 || (dimension & 0x03) != 1) {
+ throw FormatException.getFormatInstance();
+ }
+ this.bitMatrix = bitMatrix;
+ }
+
+ /**
+ * <p>Reads format information from one of its two locations within the QR Code.</p>
+ *
+ * @return {@link FormatInformation} encapsulating the QR Code's format info
+ * @throws FormatException if both format information locations cannot be parsed as
+ * the valid encoding of format information
+ */
+ FormatInformation readFormatInformation() throws FormatException {
+
+ if (parsedFormatInfo != null) {
+ return parsedFormatInfo;
+ }
+
+ // Read top-left format info bits
+ int formatInfoBits1 = 0;
+ for (int i = 0; i < 6; i++) {
+ formatInfoBits1 = copyBit(i, 8, formatInfoBits1);
+ }
+ // .. and skip a bit in the timing pattern ...
+ formatInfoBits1 = copyBit(7, 8, formatInfoBits1);
+ formatInfoBits1 = copyBit(8, 8, formatInfoBits1);
+ formatInfoBits1 = copyBit(8, 7, formatInfoBits1);
+ // .. and skip a bit in the timing pattern ...
+ for (int j = 5; j >= 0; j--) {
+ formatInfoBits1 = copyBit(8, j, formatInfoBits1);
+ }
+
+ // Read the top-right/bottom-left pattern too
+ int dimension = bitMatrix.getHeight();
+ int formatInfoBits2 = 0;
+ int jMin = dimension - 7;
+ for (int j = dimension - 1; j >= jMin; j--) {
+ formatInfoBits2 = copyBit(8, j, formatInfoBits2);
+ }
+ for (int i = dimension - 8; i < dimension; i++) {
+ formatInfoBits2 = copyBit(i, 8, formatInfoBits2);
+ }
+
+ parsedFormatInfo = FormatInformation.decodeFormatInformation(formatInfoBits1, formatInfoBits2);
+ if (parsedFormatInfo != null) {
+ return parsedFormatInfo;
+ }
+ throw FormatException.getFormatInstance();
+ }
+
+ /**
+ * <p>Reads version information from one of its two locations within the QR Code.</p>
+ *
+ * @return {@link Version} encapsulating the QR Code's version
+ * @throws FormatException if both version information locations cannot be parsed as
+ * the valid encoding of version information
+ */
+ Version readVersion() throws FormatException {
+
+ if (parsedVersion != null) {
+ return parsedVersion;
+ }
+
+ int dimension = bitMatrix.getHeight();
+
+ int provisionalVersion = (dimension - 17) >> 2;
+ if (provisionalVersion <= 6) {
+ return Version.getVersionForNumber(provisionalVersion);
+ }
+
+ // Read top-right version info: 3 wide by 6 tall
+ int versionBits = 0;
+ int ijMin = dimension - 11;
+ for (int j = 5; j >= 0; j--) {
+ for (int i = dimension - 9; i >= ijMin; i--) {
+ versionBits = copyBit(i, j, versionBits);
+ }
+ }
+
+ parsedVersion = Version.decodeVersionInformation(versionBits);
+ if (parsedVersion != null && parsedVersion.getDimensionForVersion() == dimension) {
+ return parsedVersion;
+ }
+
+ // Hmm, failed. Try bottom left: 6 wide by 3 tall
+ versionBits = 0;
+ for (int i = 5; i >= 0; i--) {
+ for (int j = dimension - 9; j >= ijMin; j--) {
+ versionBits = copyBit(i, j, versionBits);
+ }
+ }
+
+ parsedVersion = Version.decodeVersionInformation(versionBits);
+ if (parsedVersion != null && parsedVersion.getDimensionForVersion() == dimension) {
+ return parsedVersion;
+ }
+ throw FormatException.getFormatInstance();
+ }
+
+ private int copyBit(int i, int j, int versionBits) {
+ return bitMatrix.get(i, j) ? (versionBits << 1) | 0x1 : versionBits << 1;
+ }
+
+ /**
+ * <p>Reads the bits in the {@link BitMatrix} representing the finder pattern in the
+ * correct order in order to reconstitute the codewords bytes contained within the
+ * QR Code.</p>
+ *
+ * @return bytes encoded within the QR Code
+ * @throws FormatException if the exact number of bytes expected is not read
+ */
+ byte[] readCodewords() throws FormatException {
+
+ FormatInformation formatInfo = readFormatInformation();
+ Version version = readVersion();
+
+ // Get the data mask for the format used in this QR Code. This will exclude
+ // some bits from reading as we wind through the bit matrix.
+ DataMask dataMask = DataMask.forReference((int) formatInfo.getDataMask());
+ int dimension = bitMatrix.getHeight();
+ dataMask.unmaskBitMatrix(bitMatrix, dimension);
+
+ BitMatrix functionPattern = version.buildFunctionPattern();
+
+ boolean readingUp = true;
+ byte[] result = new byte[version.getTotalCodewords()];
+ int resultOffset = 0;
+ int currentByte = 0;
+ int bitsRead = 0;
+ // Read columns in pairs, from right to left
+ for (int j = dimension - 1; j > 0; j -= 2) {
+ if (j == 6) {
+ // Skip whole column with vertical alignment pattern;
+ // saves time and makes the other code proceed more cleanly
+ j--;
+ }
+ // Read alternatingly from bottom to top then top to bottom
+ for (int count = 0; count < dimension; count++) {
+ int i = readingUp ? dimension - 1 - count : count;
+ for (int col = 0; col < 2; col++) {
+ // Ignore bits covered by the function pattern
+ if (!functionPattern.get(j - col, i)) {
+ // Read a bit
+ bitsRead++;
+ currentByte <<= 1;
+ if (bitMatrix.get(j - col, i)) {
+ currentByte |= 1;
+ }
+ // If we've made a whole byte, save it off
+ if (bitsRead == 8) {
+ result[resultOffset++] = (byte) currentByte;
+ bitsRead = 0;
+ currentByte = 0;
+ }
+ }
+ }
+ }
+ readingUp ^= true; // readingUp = !readingUp; // switch directions
+ }
+ if (resultOffset != version.getTotalCodewords()) {
+ throw FormatException.getFormatInstance();
+ }
+ return result;
+ }
+
+}
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