Package com.google.zxing.common

Class BitMatrix

java.lang.Object
com.google.zxing.common.BitMatrix
All Implemented Interfaces:
Cloneable
public final class BitMatrix
extends Object
implements Cloneable

Represents a 2D matrix of bits. In function arguments below, and throughout the common module, x is the column position, and y is the row position. The ordering is always x, y. The origin is at the top-left.

Internally the bits are represented in a 1-D array of 32-bit ints. However, each row begins with a new int. This is done intentionally so that we can copy out a row into a BitArray very efficiently.

The ordering of bits is row-major. Within each int, the least significant bits are used first, meaning they represent lower x values. This is compatible with BitArray's implementation.

Author:
Sean Owen, dswitkin@google.com (Daniel Switkin)

  • Constructor Details

    • BitMatrix

      public BitMatrix​(int dimension)
      Creates an empty square BitMatrix.
      Parameters:
      dimension - height and width

    • BitMatrix

      public BitMatrix​(int width, int height)
      Creates an empty BitMatrix.
      Parameters:
      width - bit matrix width
      height - bit matrix height

  • Method Details

    • parse

      public static BitMatrix parse​(boolean[][] image)
      Interprets a 2D array of booleans as a BitMatrix, where "true" means an "on" bit.
      Parameters:
      image - bits of the image, as a row-major 2D array. Elements are arrays representing rows
      Returns:
      BitMatrix representation of image

    • parse

      public static BitMatrix parse​(String stringRepresentation, String setString, String unsetString)

    • get

      public boolean get​(int x, int y)

      Gets the requested bit, where true means black.

      Parameters:
      x - The horizontal component (i.e. which column)
      y - The vertical component (i.e. which row)
      Returns:
      value of given bit in matrix

    • set

      public void set​(int x, int y)

      Sets the given bit to true.

      Parameters:
      x - The horizontal component (i.e. which column)
      y - The vertical component (i.e. which row)

    • unset

      public void unset​(int x, int y)

    • flip

      public void flip​(int x, int y)

      Flips the given bit.

      Parameters:
      x - The horizontal component (i.e. which column)
      y - The vertical component (i.e. which row)

    • xor

      public void xor​(BitMatrix mask)
      Exclusive-or (XOR): Flip the bit in this BitMatrix if the corresponding mask bit is set.
      Parameters:
      mask - XOR mask

    • clear

      public void clear()
      Clears all bits (sets to false).

    • setRegion

      public void setRegion​(int left, int top, int width, int height)

      Sets a square region of the bit matrix to true.

      Parameters:
      left - The horizontal position to begin at (inclusive)
      top - The vertical position to begin at (inclusive)
      width - The width of the region
      height - The height of the region

    • getRow

      public BitArray getRow​(int y, BitArray row)
      A fast method to retrieve one row of data from the matrix as a BitArray.
      Parameters:
      y - The row to retrieve
      row - An optional caller-allocated BitArray, will be allocated if null or too small
      Returns:
      The resulting BitArray - this reference should always be used even when passing your own row

    • setRow

      public void setRow​(int y, BitArray row)
      Parameters:
      y - row to set
      row - BitArray to copy from

    • rotate180

      public void rotate180()
      Modifies this BitMatrix to represent the same but rotated 180 degrees

    • getEnclosingRectangle

      public int[] getEnclosingRectangle()
      This is useful in detecting the enclosing rectangle of a 'pure' barcode.
      Returns:
      left,top,width,height enclosing rectangle of all 1 bits, or null if it is all white

    • getTopLeftOnBit

      public int[] getTopLeftOnBit()
      This is useful in detecting a corner of a 'pure' barcode.
      Returns:
      x,y coordinate of top-left-most 1 bit, or null if it is all white

    • getBottomRightOnBit

      public int[] getBottomRightOnBit()

    • getWidth

      public int getWidth()
      Returns:
      The width of the matrix

    • getHeight

      public int getHeight()
      Returns:
      The height of the matrix

    • getRowSize

      public int getRowSize()
      Returns:
      The row size of the matrix

    • equals

      public boolean equals​(Object o)
      Overrides:
      equals in class Object

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object

    • toString

      public String toString()
      Overrides:
      toString in class Object
      Returns:
      string representation using "X" for set and " " for unset bits

    • toString

      public String toString​(String setString, String unsetString)
      Parameters:
      setString - representation of a set bit
      unsetString - representation of an unset bit
      Returns:
      string representation of entire matrix utilizing given strings

    • toString

      @Deprecated public String toString​(String setString, String unsetString, String lineSeparator)
      Deprecated.
      call toString(String,String) only, which uses \n line separator always
      Parameters:
      setString - representation of a set bit
      unsetString - representation of an unset bit
      lineSeparator - newline character in string representation
      Returns:
      string representation of entire matrix utilizing given strings and line separator

    • clone

      public BitMatrix clone()
      Overrides:
      clone in class Object