com.google.zxing.common
Class BitMatrix

java.lang.Object
  com.google.zxing.common.BitMatrix

public final class BitMatrix
extends Object

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.

Since:

BlackBerry API 6.0.0

Field Summary
int[]	bits
int	height
int	rowSize
int	width

Constructor Summary

BitMatrix(int dimension)

BitMatrix(int width, int height)

Method Summary
void	clear() Clears all bits (sets to false).
boolean	equals(Object o) Indicates whether some other object is "equal to" this one.
void	flip(int x, int y) Flips the given bit.
boolean	get(int x, int y) Gets the requested bit, where true means black.
int[]	getBottomRightOnBit()
int	getDimension() This method is for compatibility with older code.
int	getHeight()
BitArray	getRow(int y, BitArray row) A fast method to retrieve one row of data from the matrix as a BitArray.
int[]	getTopLeftOnBit() This is useful in detecting a corner of a 'pure' barcode.
int	getWidth()
int	hashCode() Returns a hash code value for the object.
void	set(int x, int y) Sets the given bit to true.
void	setRegion(int left, int top, int width, int height) Sets a square region of the bit matrix to true.
String	toString() Returns a string representation of the object.

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Field Detail

width

public final int width

Since:

BlackBerry API 6.0.0

height

public final int height

Since:

BlackBerry API 6.0.0

rowSize

public final int rowSize

Since:

BlackBerry API 6.0.0

bits

public final int[] bits

Since:

BlackBerry API 6.0.0

Constructor Detail

BitMatrix

public BitMatrix(int dimension)

Since:

BlackBerry API 6.0.0

BitMatrix

public BitMatrix(int width,
                 int height)

Since:

BlackBerry API 6.0.0

Method Detail

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

Since:

BlackBerry API 6.0.0

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)

Since:

BlackBerry API 6.0.0

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)

Since:

BlackBerry API 6.0.0

clear

public void clear()

Clears all bits (sets to false).

Since:

BlackBerry API 6.0.0

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

Since:

BlackBerry API 6.0.0

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

Since:

BlackBerry API 6.0.0

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

Since:

BlackBerry API 7.0.0

getBottomRightOnBit

public int[] getBottomRightOnBit()

Since:

BlackBerry API 7.0.0

getWidth

public int getWidth()

Returns:

The width of the matrix

Since:

BlackBerry API 6.0.0

getHeight

public int getHeight()

Returns:

The height of the matrix

Since:

BlackBerry API 6.0.0

getDimension

public int getDimension()

This method is for compatibility with older code. It's only logical to call if the matrix is square, so I'm throwing if that's not the case.

Returns:

row/column dimension of this matrix

Since:

BlackBerry API 6.0.0

equals

public boolean equals(Object o)

Description copied from class: Object

Indicates whether some other object is "equal to" this one.

The equals method implements an equivalence relation:

• It is reflexive: for any reference value x, x.equals(x) should return true.
• It is symmetric: for any reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.
• It is transitive: for any reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.
• It is consistent: for any reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the object is modified.
• For any non-null reference value x, x.equals(null) should return false.

The equals method for class Object implements the most discriminating possible equivalence relation on objects; that is, for any reference values x and y, this method returns true if and only if x and y refer to the same object (x==y has the value true).

Overrides:

equals in class Object

Parameters:

o - the reference object with which to compare.

Returns:

true if this object is the same as the obj argument; false otherwise.

See Also:

Boolean.hashCode(), Hashtable

Since:

BlackBerry API 7.0.0

hashCode

public int hashCode()

Description copied from class: Object

Returns a hash code value for the object. This method is supported for the benefit of hashtables such as those provided by java.util.Hashtable.

The general contract of hashCode is:

• Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.
• If two objects are equal according to the equals(Object) method, then calling the hashCode method on each of the two objects must produce the same integer result.
• It is not required that if two objects are unequal according to the Object.equals(java.lang.Object) method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hashtables.

As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the Java^TM programming language.)

Overrides:

hashCode in class Object

Returns:

a hash code value for this object.

See Also:

Object.equals(java.lang.Object), Hashtable

Since:

BlackBerry API 7.0.0

toString

public String toString()

Description copied from class: Object

Returns a string representation of the object. In general, the toString method returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommended that all subclasses override this method.

The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of:

 getClass().getName() + '@' + Integer.toHexString(hashCode())
 

Overrides:

toString in class Object

Returns:

a string representation of the object.

Since:

BlackBerry API 6.0.0