com.google.zxing
Class LuminanceSource

java.lang.Object
  extended by com.google.zxing.LuminanceSource
Direct Known Subclasses:
BitmapLuminanceSource

public abstract class LuminanceSource
extends Object

The purpose of this class hierarchy is to abstract different bitmap implementations across platforms into a standard interface for requesting greyscale luminance values. The interface only provides immutable methods; therefore crop and rotation create copies. This is to ensure that one Reader does not modify the original luminance source and leave it in an unknown state for other Readers in the chain.

Since:
BlackBerry API 6.0.0

Constructor Summary
protected LuminanceSource(int width, int height)
           
 
Method Summary
 LuminanceSource crop(int left, int top, int width, int height)
          Returns a new object with cropped image data.
 int getHeight()
           
abstract  byte[] getMatrix()
          Fetches luminance data for the underlying bitmap.
abstract  byte[] getRow(int y, byte[] row)
          Fetches one row of luminance data from the underlying platform's bitmap.
 int getWidth()
           
 boolean isCropSupported()
           
 boolean isRotateSupported()
           
 LuminanceSource rotateCounterClockwise()
          Returns a new object with rotated image data.
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 



Constructor Detail

LuminanceSource

protected LuminanceSource(int width,
                          int height)
Since:
BlackBerry API 6.0.0


Method Detail

getRow

public abstract byte[] getRow(int y,
                              byte[] row)
Fetches one row of luminance data from the underlying platform's bitmap. Values range from 0 (black) to 255 (white). Because Java does not have an unsigned byte type, callers will have to bitwise and with 0xff for each value. It is preferable for implementations of this method to only fetch this row rather than the whole image, since no 2D Readers may be installed and getMatrix() may never be called.

Parameters:
y - The row to fetch, 0 <= y < getHeight().
row - An optional preallocated array. If null or too small, it will be ignored. Always use the returned object, and ignore the .length of the array.
Returns:
An array containing the luminance data.
Since:
BlackBerry API 6.0.0

getMatrix

public abstract byte[] getMatrix()
Fetches luminance data for the underlying bitmap. Values should be fetched using: int luminance = array[y * width + x] & 0xff;

Returns:
A row-major 2D array of luminance values. Do not use result.length as it may be larger than width * height bytes on some platforms. Do not modify the contents of the result.
Since:
BlackBerry API 6.0.0

getWidth

public final int getWidth()
Returns:
The width of the bitmap.
Since:
BlackBerry API 6.0.0

getHeight

public final int getHeight()
Returns:
The height of the bitmap.
Since:
BlackBerry API 6.0.0

isCropSupported

public boolean isCropSupported()
Returns:
Whether this subclass supports cropping.
Since:
BlackBerry API 6.0.0

crop

public LuminanceSource crop(int left,
                            int top,
                            int width,
                            int height)
Returns a new object with cropped image data. Implementations may keep a reference to the original data rather than a copy. Only callable if isCropSupported() is true.

Parameters:
left - The left coordinate, 0 <= left < getWidth().
top - The top coordinate, 0 <= top <= getHeight().
width - The width of the rectangle to crop.
height - The height of the rectangle to crop.
Returns:
A cropped version of this object.
Since:
BlackBerry API 6.0.0

isRotateSupported

public boolean isRotateSupported()
Returns:
Whether this subclass supports counter-clockwise rotation.
Since:
BlackBerry API 6.0.0

rotateCounterClockwise

public LuminanceSource rotateCounterClockwise()
Returns a new object with rotated image data. Only callable if isRotateSupported() is true.

Returns:
A rotated version of this object.
Since:
BlackBerry API 6.0.0





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