Add parts of zxing library to generate qr codes

OpenPGP-Keychain/src/com/google/zxing/qrcode/decoder/DataBlock.java

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+/*
+ * 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;
+
+/**
+ * <p>Encapsulates a block of data within a QR Code. QR Codes may split their data into
+ * multiple blocks, each of which is a unit of data and error-correction codewords. Each
+ * is represented by an instance of this class.</p>
+ *
+ * @author Sean Owen
+ */
+final class DataBlock {
+
+  private final int numDataCodewords;
+  private final byte[] codewords;
+
+  private DataBlock(int numDataCodewords, byte[] codewords) {
+    this.numDataCodewords = numDataCodewords;
+    this.codewords = codewords;
+  }
+
+  /**
+   * <p>When QR Codes use multiple data blocks, they are actually interleaved.
+   * That is, the first byte of data block 1 to n is written, then the second bytes, and so on. This
+   * method will separate the data into original blocks.</p>
+   *
+   * @param rawCodewords bytes as read directly from the QR Code
+   * @param version version of the QR Code
+   * @param ecLevel error-correction level of the QR Code
+   * @return DataBlocks containing original bytes, "de-interleaved" from representation in the
+   *         QR Code
+   */
+  static DataBlock[] getDataBlocks(byte[] rawCodewords,
+                                   Version version,
+                                   ErrorCorrectionLevel ecLevel) {
+
+    if (rawCodewords.length != version.getTotalCodewords()) {
+      throw new IllegalArgumentException();
+    }
+
+    // Figure out the number and size of data blocks used by this version and
+    // error correction level
+    Version.ECBlocks ecBlocks = version.getECBlocksForLevel(ecLevel);
+
+    // First count the total number of data blocks
+    int totalBlocks = 0;
+    Version.ECB[] ecBlockArray = ecBlocks.getECBlocks();
+    for (int i = 0; i < ecBlockArray.length; i++) {
+      totalBlocks += ecBlockArray[i].getCount();
+    }
+
+    // Now establish DataBlocks of the appropriate size and number of data codewords
+    DataBlock[] result = new DataBlock[totalBlocks];
+    int numResultBlocks = 0;
+    for (int j = 0; j < ecBlockArray.length; j++) {
+      Version.ECB ecBlock = ecBlockArray[j];
+      for (int i = 0; i < ecBlock.getCount(); i++) {
+        int numDataCodewords = ecBlock.getDataCodewords();
+        int numBlockCodewords = ecBlocks.getECCodewordsPerBlock() + numDataCodewords;
+        result[numResultBlocks++] = new DataBlock(numDataCodewords, new byte[numBlockCodewords]);
+      }
+    }
+
+    // All blocks have the same amount of data, except that the last n
+    // (where n may be 0) have 1 more byte. Figure out where these start.
+    int shorterBlocksTotalCodewords = result[0].codewords.length;
+    int longerBlocksStartAt = result.length - 1;
+    while (longerBlocksStartAt >= 0) {
+      int numCodewords = result[longerBlocksStartAt].codewords.length;
+      if (numCodewords == shorterBlocksTotalCodewords) {
+        break;
+      }
+      longerBlocksStartAt--;
+    }
+    longerBlocksStartAt++;
+
+    int shorterBlocksNumDataCodewords = shorterBlocksTotalCodewords - ecBlocks.getECCodewordsPerBlock();
+    // The last elements of result may be 1 element longer;
+    // first fill out as many elements as all of them have
+    int rawCodewordsOffset = 0;
+    for (int i = 0; i < shorterBlocksNumDataCodewords; i++) {
+      for (int j = 0; j < numResultBlocks; j++) {
+        result[j].codewords[i] = rawCodewords[rawCodewordsOffset++];
+      }
+    }
+    // Fill out the last data block in the longer ones
+    for (int j = longerBlocksStartAt; j < numResultBlocks; j++) {
+      result[j].codewords[shorterBlocksNumDataCodewords] = rawCodewords[rawCodewordsOffset++];
+    }
+    // Now add in error correction blocks
+    int max = result[0].codewords.length;
+    for (int i = shorterBlocksNumDataCodewords; i < max; i++) {
+      for (int j = 0; j < numResultBlocks; j++) {
+        int iOffset = j < longerBlocksStartAt ? i : i + 1;
+        result[j].codewords[iOffset] = rawCodewords[rawCodewordsOffset++];
+      }
+    }
+    return result;
+  }
+
+  int getNumDataCodewords() {
+    return numDataCodewords;
+  }
+
+  byte[] getCodewords() {
+    return codewords;
+  }
+
+}