/*\r
- * Copyright 2007 Google Inc.\r
+ * Copyright 2007 ZXing authors\r
*\r
* Licensed under the Apache License, Version 2.0 (the "License");\r
* you may not use this file except in compliance with the License.\r
\r
package com.google.zxing.qrcode.decoder;\r
\r
-import com.google.zxing.ReaderException;\r
+import com.google.zxing.ChecksumException;\r
+import com.google.zxing.FormatException;\r
+import com.google.zxing.NotFoundException;\r
import com.google.zxing.common.BitMatrix;\r
+import com.google.zxing.common.DecoderResult;\r
+import com.google.zxing.common.reedsolomon.GF256;\r
import com.google.zxing.common.reedsolomon.ReedSolomonDecoder;\r
import com.google.zxing.common.reedsolomon.ReedSolomonException;\r
\r
+import java.util.Hashtable;\r
+\r
/**\r
- * @author srowen@google.com (Sean Owen)\r
+ * <p>The main class which implements QR Code decoding -- as opposed to locating and extracting\r
+ * the QR Code from an image.</p>\r
+ *\r
+ * @author Sean Owen\r
*/\r
public final class Decoder {\r
\r
- private Decoder() {\r
+ private final ReedSolomonDecoder rsDecoder;\r
+\r
+ public Decoder() {\r
+ rsDecoder = new ReedSolomonDecoder(GF256.QR_CODE_FIELD);\r
}\r
\r
- public static String decode(boolean[][] image) throws ReaderException {\r
+ public DecoderResult decode(boolean[][] image)\r
+ throws ChecksumException, FormatException, NotFoundException {\r
+ return decode(image, null);\r
+ }\r
+\r
+ /**\r
+ * <p>Convenience method that can decode a QR Code represented as a 2D array of booleans.\r
+ * "true" is taken to mean a black module.</p>\r
+ *\r
+ * @param image booleans representing white/black QR Code modules\r
+ * @return text and bytes encoded within the QR Code\r
+ * @throws FormatException if the QR Code cannot be decoded\r
+ * @throws ChecksumException if error correction fails\r
+ */\r
+ public DecoderResult decode(boolean[][] image, Hashtable hints) throws ChecksumException, FormatException {\r
int dimension = image.length;\r
BitMatrix bits = new BitMatrix(dimension);\r
for (int i = 0; i < dimension; i++) {\r
for (int j = 0; j < dimension; j++) {\r
if (image[i][j]) {\r
- bits.set(i, j);\r
+ bits.set(j, i);\r
}\r
}\r
}\r
- return decode(bits);\r
+ return decode(bits, hints);\r
}\r
\r
- public static String decode(BitMatrix bits) throws ReaderException {\r
+ public DecoderResult decode(BitMatrix bits) throws ChecksumException, FormatException {\r
+ return decode(bits, null);\r
+ }\r
+\r
+ /**\r
+ * <p>Decodes a QR Code represented as a {@link BitMatrix}. A 1 or "true" is taken to mean a black module.</p>\r
+ *\r
+ * @param bits booleans representing white/black QR Code modules\r
+ * @return text and bytes encoded within the QR Code\r
+ * @throws FormatException if the QR Code cannot be decoded\r
+ * @throws ChecksumException if error correction fails\r
+ */\r
+ public DecoderResult decode(BitMatrix bits, Hashtable hints) throws FormatException, ChecksumException {\r
+\r
+ // Construct a parser and read version, error-correction level\r
BitMatrixParser parser = new BitMatrixParser(bits);\r
Version version = parser.readVersion();\r
ErrorCorrectionLevel ecLevel = parser.readFormatInformation().getErrorCorrectionLevel();\r
+\r
+ // Read codewords\r
byte[] codewords = parser.readCodewords();\r
+ // Separate into data blocks\r
DataBlock[] dataBlocks = DataBlock.getDataBlocks(codewords, version, ecLevel);\r
+\r
+ // Count total number of data bytes\r
int totalBytes = 0;\r
for (int i = 0; i < dataBlocks.length; i++) {\r
totalBytes += dataBlocks[i].getNumDataCodewords();\r
}\r
byte[] resultBytes = new byte[totalBytes];\r
int resultOffset = 0;\r
+\r
+ // Error-correct and copy data blocks together into a stream of bytes\r
for (int j = 0; j < dataBlocks.length; j++) {\r
DataBlock dataBlock = dataBlocks[j];\r
byte[] codewordBytes = dataBlock.getCodewords();\r
}\r
}\r
\r
- return DecodedBitStreamParser.decode(resultBytes, version);\r
+ // Decode the contents of that stream of bytes\r
+ return DecodedBitStreamParser.decode(resultBytes, version, ecLevel, hints);\r
}\r
\r
- private static void correctErrors(byte[] codewordBytes, int numDataCodewords)\r
- throws ReaderException {\r
+ /**\r
+ * <p>Given data and error-correction codewords received, possibly corrupted by errors, attempts to\r
+ * correct the errors in-place using Reed-Solomon error correction.</p>\r
+ *\r
+ * @param codewordBytes data and error correction codewords\r
+ * @param numDataCodewords number of codewords that are data bytes\r
+ * @throws ChecksumException if error correction fails\r
+ */\r
+ private void correctErrors(byte[] codewordBytes, int numDataCodewords) throws ChecksumException {\r
int numCodewords = codewordBytes.length;\r
+ // First read into an array of ints\r
int[] codewordsInts = new int[numCodewords];\r
for (int i = 0; i < numCodewords; i++) {\r
codewordsInts[i] = codewordBytes[i] & 0xFF;\r
}\r
int numECCodewords = codewordBytes.length - numDataCodewords;\r
try {\r
- ReedSolomonDecoder.decode(codewordsInts, numECCodewords);\r
+ rsDecoder.decode(codewordsInts, numECCodewords);\r
} catch (ReedSolomonException rse) {\r
- throw new ReaderException(rse.toString());\r
+ throw ChecksumException.getChecksumInstance();\r
}\r
+ // Copy back into array of bytes -- only need to worry about the bytes that were data\r
+ // We don't care about errors in the error-correction codewords\r
for (int i = 0; i < numDataCodewords; i++) {\r
codewordBytes[i] = (byte) codewordsInts[i];\r
}\r
projects / zxing.git / blobdiff