content: /*
   * 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.ailiwean.core.zxing.core.qrcode.decoder;
  
  
  import com.ailiwean.core.zxing.core.common.BitMatrix;
  
  /**
   * <p>Encapsulates data masks for the data bits in a QR code, per ISO 18004:2006 6.8. Implementations
   * of this class can un-mask a raw BitMatrix. For simplicity, they will unmask the entire BitMatrix,
   * including areas used for finder patterns, timing patterns, etc. These areas should be unused
   * after the point they are unmasked anyway.</p>
   *
   * <p>Note that the diagram in section 6.8.1 is misleading since it indicates that i is column position
   * and j is row position. In fact, as the text says, i is row position and j is column position.</p>
   *
   * @author Sean Owen
   */
  enum DataMask {
  
    // See ISO 18004:2006 6.8.1
  
    /**
     * 000: mask bits for which (x + y) mod 2 == 0
     */
    DATA_MASK_000() {
      @Override
      boolean isMasked(int i, int j) {
        return ((i + j) & 0x01) == 0;
      }
    },
  
    /**
     * 001: mask bits for which x mod 2 == 0
     */
    DATA_MASK_001() {
      @Override
      boolean isMasked(int i, int j) {
        return (i & 0x01) == 0;
      }
    },
  
    /**
     * 010: mask bits for which y mod 3 == 0
     */
    DATA_MASK_010() {
      @Override
      boolean isMasked(int i, int j) {
        return j % 3 == 0;
      }
    },
  
    /**
     * 011: mask bits for which (x + y) mod 3 == 0
     */
    DATA_MASK_011() {
      @Override
      boolean isMasked(int i, int j) {
        return (i + j) % 3 == 0;
      }
    },
  
    /**
     * 100: mask bits for which (x/2 + y/3) mod 2 == 0
     */
    DATA_MASK_100() {
      @Override
      boolean isMasked(int i, int j) {
        return (((i / 2) + (j / 3)) & 0x01) == 0;
      }
    },
  
    /**
     * 101: mask bits for which xy mod 2 + xy mod 3 == 0
     * equivalently, such that xy mod 6 == 0
     */
    DATA_MASK_101() {
      @Override
      boolean isMasked(int i, int j) {
        return (i * j) % 6 == 0;
      }
    },
  
    /**
     * 110: mask bits for which (xy mod 2 + xy mod 3) mod 2 == 0
     * equivalently, such that xy mod 6 < 3
     */
    DATA_MASK_110() {
      @Override
      boolean isMasked(int i, int j) {
        return ((i * j) % 6) < 3;
      }
    },
  
    /**
     * 111: mask bits for which ((x+y)mod 2 + xy mod 3) mod 2 == 0
     * equivalently, such that (x + y + xy mod 3) mod 2 == 0
     */
    DATA_MASK_111() {
      @Override
      boolean isMasked(int i, int j) {
        return ((i + j + ((i * j) % 3)) & 0x01) == 0;
      }
    };
  
    // End of enum constants.
  
  
    /**
     * <p>Implementations of this method reverse the data masking process applied to a QR Code and
     * make its bits ready to read.</p>
     *
     * @param bits representation of QR Code bits
     * @param dimension dimension of QR Code, represented by bits, being unmasked
     */
    final void unmaskBitMatrix(BitMatrix bits, int dimension) {
      for (int i = 0; i < dimension; i++) {
        for (int j = 0; j < dimension; j++) {
          if (isMasked(i, j)) {
            bits.flip(j, i);
          }
        }
      }
    }
  
    abstract boolean isMasked(int i, int j);
  
  }
  