Add minimal support for FNC1 mode in QR Code

[zxing.git] / core / src / com / google / zxing / qrcode / decoder / BitMatrixParser.java

diff --git a/core/src/com/google/zxing/qrcode/decoder/BitMatrixParser.java b/core/src/com/google/zxing/qrcode/decoder/BitMatrixParser.java
index 7e20d75..27f19ad 100644 (file)
--- a/core/src/com/google/zxing/qrcode/decoder/BitMatrixParser.java
+++ b/core/src/com/google/zxing/qrcode/decoder/BitMatrixParser.java
@@ -1,5 +1,5 @@
 /*\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
@@ -29,8 +29,8 @@ final class BitMatrixParser {
   private FormatInformation parsedFormatInfo;\r
 \r
   /**\r
-   * @throws com.google.zxing.ReaderException\r
-   *          if dimension is not >= 21 and 1 mod 4\r
+   * @param bitMatrix {@link BitMatrix} to parse\r
+   * @throws ReaderException if dimension is not >= 21 and 1 mod 4\r
    */\r
   BitMatrixParser(BitMatrix bitMatrix) throws ReaderException {\r
     int dimension = bitMatrix.getDimension();\r
@@ -40,6 +40,13 @@ final class BitMatrixParser {
     this.bitMatrix = bitMatrix;\r
   }\r
 \r
+  /**\r
+   * <p>Reads format information from one of its two locations within the QR Code.</p>\r
+   *\r
+   * @return {@link FormatInformation} encapsulating the QR Code's format info\r
+   * @throws ReaderException if both format information locations cannot be parsed as\r
+   * the valid encoding of format information\r
+   */\r
   FormatInformation readFormatInformation() throws ReaderException {\r
 \r
     if (parsedFormatInfo != null) {\r
@@ -83,6 +90,13 @@ final class BitMatrixParser {
     throw new ReaderException("Could not decode format information");\r
   }\r
 \r
+  /**\r
+   * <p>Reads version information from one of its two locations within the QR Code.</p>\r
+   *\r
+   * @return {@link Version} encapsulating the QR Code's version\r
+   * @throws ReaderException if both version information locations cannot be parsed as\r
+   * the valid encoding of version information\r
+   */\r
   Version readVersion() throws ReaderException {\r
 \r
     if (parsedVersion != null) {\r
@@ -130,11 +144,21 @@ final class BitMatrixParser {
     return bitMatrix.get(i, j) ? (versionBits << 1) | 0x1 : versionBits << 1;\r
   }\r
 \r
+  /**\r
+   * <p>Reads the bits in the {@link BitMatrix} representing the finder pattern in the\r
+   * correct order in order to reconstitute the codewords bytes contained within the\r
+   * QR Code.</p>\r
+   *\r
+   * @return bytes encoded within the QR Code\r
+   * @throws ReaderException if the exact number of bytes expected is not read\r
+   */\r
   byte[] readCodewords() throws ReaderException {\r
 \r
     FormatInformation formatInfo = readFormatInformation();\r
     Version version = readVersion();\r
 \r
+    // Get the data mask for the format used in this QR Code. This will exclude\r
+    // some bits from reading as we wind through the bit matrix.\r
     DataMask dataMask = DataMask.forReference((int) formatInfo.getDataMask());\r
     int dimension = bitMatrix.getDimension();\r
     dataMask.unmaskBitMatrix(bitMatrix.getBits(), dimension);\r
@@ -146,21 +170,26 @@ final class BitMatrixParser {
     int resultOffset = 0;\r
     int currentByte = 0;\r
     int bitsRead = 0;\r
+    // Read columns in pairs, from right to left\r
     for (int j = dimension - 1; j > 0; j -= 2) {\r
       if (j == 6) {\r
         // Skip whole column with vertical alignment pattern;\r
         // saves time and makes the other code proceed more cleanly\r
         j--;\r
       }\r
+      // Read alternatingly from bottom to top then top to bottom\r
       for (int count = 0; count < dimension; count++) {\r
         int i = readingUp ? dimension - 1 - count : count;\r
         for (int col = 0; col < 2; col++) {\r
+          // Ignore bits covered by the function pattern\r
           if (!functionPattern.get(i, j - col)) {\r
+            // Read a bit\r
             bitsRead++;\r
             currentByte <<= 1;\r
             if (bitMatrix.get(i, j - col)) {\r
               currentByte |= 1;\r
             }\r
+            // If we've made a whole byte, save it off\r
             if (bitsRead == 8) {\r
               result[resultOffset++] = (byte) currentByte;\r
               bitsRead = 0;\r