com.sun.pdfview.decode

Class PNGPredictor

public class PNGPredictor extends Predictor

Undo prediction based on the PNG algorithm.
Constructor Summary
PNGPredictor()
Creates a new instance of PNGPredictor
Method Summary
protected voiddoAverageLine(byte[] curLine, byte[] prevLine)
Return the value of the average algorithm on the line (compare bytes to the average of the previous byte of the same color and the same byte on the previous line)
protected voiddoPaethLine(byte[] curLine, byte[] prevLine)
Return the value of the average algorithm on the line (compare bytes to the average of the previous byte of the same color and the same byte on the previous line)
protected voiddoSubLine(byte[] curLine)
Return the value of the Sub algorithm on the line (compare bytes to the previous byte of the same color on this line).
protected voiddoUpLine(byte[] curLine, byte[] prevLine)
Return the value of the up algorithm on the line (compare bytes to the same byte in the previous line)
protected intpaeth(int left, int up, int upLeft)
The paeth algorithm
ByteBufferunpredict(ByteBuffer imageData)
Undo data based on the png algorithm

Constructor Detail

PNGPredictor

public PNGPredictor()
Creates a new instance of PNGPredictor

Method Detail

doAverageLine

protected void doAverageLine(byte[] curLine, byte[] prevLine)
Return the value of the average algorithm on the line (compare bytes to the average of the previous byte of the same color and the same byte on the previous line)

doPaethLine

protected void doPaethLine(byte[] curLine, byte[] prevLine)
Return the value of the average algorithm on the line (compare bytes to the average of the previous byte of the same color and the same byte on the previous line)

doSubLine

protected void doSubLine(byte[] curLine)
Return the value of the Sub algorithm on the line (compare bytes to the previous byte of the same color on this line).

doUpLine

protected void doUpLine(byte[] curLine, byte[] prevLine)
Return the value of the up algorithm on the line (compare bytes to the same byte in the previous line)

paeth

protected int paeth(int left, int up, int upLeft)
The paeth algorithm

unpredict

public ByteBuffer unpredict(ByteBuffer imageData)
Undo data based on the png algorithm