java.lang.Object
com.google.zxing.qrcode.encoder.MaskUtil
final class MaskUtilextends Object
Utility class for QR code mask operations.

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    private static final int
    N1
    Penalty weight for runs of five like modules, spec section 6.8.2.1.
    private static final int
    N2
    Penalty weight for 2x2 blocks of like modules.
    private static final int
    N3
    Penalty weight for finder-like patterns.
    private static final int
    N4
    Penalty weight for dark-light imbalance.

  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
    private
    MaskUtil()
    Utility class, not intended for instantiation.

  • Method Summary

    Private Methods
    Modifier and Type
    Method
    Description
    (package private) static int
    applyMaskPenaltyRule1(ByteMatrix matrix)
    Apply mask penalty rule 1 and return the penalty.
    private static int
    applyMaskPenaltyRule1Internal(ByteMatrix matrix, boolean isHorizontal)
    Helper function for applyMaskPenaltyRule1.
    (package private) static int
    applyMaskPenaltyRule2(ByteMatrix matrix)
    Apply mask penalty rule 2 and return the penalty.
    (package private) static int
    applyMaskPenaltyRule3(ByteMatrix matrix)
    Apply mask penalty rule 3 and return the penalty.
    (package private) static int
    applyMaskPenaltyRule4(ByteMatrix matrix)
    Apply mask penalty rule 4 and return the penalty.
    (package private) static boolean
    getDataMaskBit(int maskPattern, int x, int y)
    Return the mask bit for "getMaskPattern" at "x" and "y".
    private static boolean
    isWhiteHorizontal(byte[] rowArray, int from, int to)
    Checks whether a stretch of one row is all white.
    private static boolean
    isWhiteVertical(byte[][] array, int col, int from, int to)
    Checks whether a stretch of one column is all white.

    Methods inherited from class Object

    clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Field Details

    • N1

      private static final int N1
      Penalty weight for runs of five like modules, spec section 6.8.2.1.
      See Also:

    • N2

      private static final int N2
      Penalty weight for 2x2 blocks of like modules.
      See Also:

    • N3

      private static final int N3
      Penalty weight for finder-like patterns.
      See Also:

    • N4

      private static final int N4
      Penalty weight for dark-light imbalance.
      See Also:

  • Constructor Details

    • MaskUtil

      private MaskUtil()
      Utility class, not intended for instantiation.

  • Method Details

    • applyMaskPenaltyRule1

      static int applyMaskPenaltyRule1(ByteMatrix matrix)
      Apply mask penalty rule 1 and return the penalty. Find repetitive cells with the same color and give penalty to them. Example: 00000 or 11111.
      Parameters:
      matrix - the byte matrix
      Returns:
      N1 (3) points for each run of five or more same-colored cells

    • applyMaskPenaltyRule2

      static int applyMaskPenaltyRule2(ByteMatrix matrix)
      Apply mask penalty rule 2 and return the penalty. Find 2x2 blocks with the same color and give penalty to them. This is actually equivalent to the spec's rule, which is to find MxN blocks and give a penalty proportional to (M-1)x(N-1), because this is the number of 2x2 blocks inside such a block.
      Parameters:
      matrix - the byte matrix
      Returns:
      N2 (3) points for each solid 2x2 block of one color

    • applyMaskPenaltyRule3

      static int applyMaskPenaltyRule3(ByteMatrix matrix)
      Apply mask penalty rule 3 and return the penalty. Find consecutive runs of 1:1:3:1:1:4 starting with black, or 4:1:1:3:1:1 starting with white, and give penalty to them. If we find patterns like 000010111010000, we give penalty once.
      Parameters:
      matrix - the byte matrix
      Returns:
      N3 (40) points for each 1:1:3:1:1 or 4:1:1:3:1:1 pattern

    • isWhiteHorizontal

      private static boolean isWhiteHorizontal(byte[] rowArray, int from, int to)
      Checks whether a stretch of one row is all white.
      Parameters:
      rowArray - the row's modules
      from - the first column to check
      to - the last column to check
      Returns:
      true if every module in the stretch is white

    • isWhiteVertical

      private static boolean isWhiteVertical(byte[][] array, int col, int from, int to)
      Checks whether a stretch of one column is all white.
      Parameters:
      array - the symbol's rows
      col - the column to check
      from - the first row to check
      to - the last row to check
      Returns:
      true if every module in the stretch is white

    • applyMaskPenaltyRule4

      static int applyMaskPenaltyRule4(ByteMatrix matrix)
      Apply mask penalty rule 4 and return the penalty. Calculate the ratio of dark cells and give penalty if the ratio is far from 50%. It gives 10 penalty for 5% distance.
      Parameters:
      matrix - the byte matrix
      Returns:
      N4 (10) points per 5% the dark-module ratio deviates from 50%

    • getDataMaskBit

      static boolean getDataMaskBit(int maskPattern, int x, int y)
      Return the mask bit for "getMaskPattern" at "x" and "y". See 8.8 of JISX0510:2004 for mask pattern conditions.
      Parameters:
      maskPattern - the mask pattern
      x - the x coordinate
      y - the y coordinate
      Returns:
      the mask bit

    • applyMaskPenaltyRule1Internal

      private static int applyMaskPenaltyRule1Internal(ByteMatrix matrix, boolean isHorizontal)
      Helper function for applyMaskPenaltyRule1. We need this for doing this calculation in both vertical and horizontal orders respectively.
      Parameters:
      matrix - the QR code matrix to scan
      isHorizontal - true to scan row by row, false to scan column by column
      Returns:
      the penalty for runs of five or more identical cells in any row or column of the matrix