Package org.apache.xmlgraphics.image.codec.png

Class PNGImageEncoder

java.lang.Object

org.apache.xmlgraphics.image.codec.util.ImageEncoderImpl

org.apache.xmlgraphics.image.codec.png.PNGImageEncoder

All Implemented Interfaces:

ImageEncoder

public class PNGImageEncoder
extends ImageEncoderImpl

An ImageEncoder for the PNG file format.

Since:

EA4

Field Summary

Fields

Modifier and Type	Field	Description
private byte[]	alphaPalette
private int	bitDepth
private int	bitShift
private byte[]	bluePalette
private int	bpp
private int	colorType
private boolean	compressGray
private byte[]	currRow
private DataOutputStream	dataOutput
private byte[][]	filteredRows
private byte[]	greenPalette
private int	height
private RenderedImage	image
private boolean	interlace
private static final byte[]	MAGIC
private int	numBands
private PNGEncodeParam	param
private static final int	PNG_COLOR_GRAY
private static final int	PNG_COLOR_GRAY_ALPHA
private static final int	PNG_COLOR_PALETTE
private static final int	PNG_COLOR_RGB
private static final int	PNG_COLOR_RGB_ALPHA
private byte[]	prevRow
private byte[]	redPalette
private boolean	skipAlpha
private static final float[]	SRGB_CHROMA
private int	width

Fields inherited from class org.apache.xmlgraphics.image.codec.util.ImageEncoderImpl

output

Constructor Summary

Constructors

Constructor	Description
PNGImageEncoder(OutputStream output, PNGEncodeParam param)

Method Summary

Modifier and Type	Method	Description
private static int	clamp(int val, int maxValue)
private PNGEncodeParam.Gray	createGrayParam(byte[] redPalette, byte[] greenPalette, byte[] bluePalette, byte[] alphaPalette)	Analyzes a set of palettes and determines if it can be expressed as a standard set of gray values, with zero or one values being fully transparent and the rest being fully opaque.
void	encode(RenderedImage im)	This method encodes a RenderedImage into PNG.
private void	encodePass(OutputStream os, Raster ras, int xOffset, int yOffset, int xSkip, int ySkip)
private void	writeBKGD()
private void	writeCHRM()
private void	writeGAMA()
private void	writeHIST()
private void	writeICCP()
private void	writeIDAT()
private void	writeIEND()
private void	writeIHDR()
private void	writeMagic()
private void	writePHYS()
private void	writePLTE()
private void	writePrivateChunks()
private void	writeSBIT()
private void	writeSPLT()
private void	writeSRGB()
private void	writeTEXT()
private void	writeTIME()
private void	writeTRNS()
private void	writeZTXT()

Methods inherited from class org.apache.xmlgraphics.image.codec.util.ImageEncoderImpl

encode, getOutputStream, getParam, setParam

Methods inherited from class java.lang.Object

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

Field Details

PNG_COLOR_GRAY

private static final int PNG_COLOR_GRAY

See Also:

• Constant Field Values

PNG_COLOR_RGB

private static final int PNG_COLOR_RGB

See Also:

• Constant Field Values

PNG_COLOR_PALETTE

private static final int PNG_COLOR_PALETTE

See Also:

• Constant Field Values

PNG_COLOR_GRAY_ALPHA

private static final int PNG_COLOR_GRAY_ALPHA

See Also:

• Constant Field Values

PNG_COLOR_RGB_ALPHA

private static final int PNG_COLOR_RGB_ALPHA

See Also:

• Constant Field Values

MAGIC

private static final byte[] MAGIC

param

private PNGEncodeParam param

image

private RenderedImage image

width

private int width

height

private int height

bitDepth

private int bitDepth

bitShift

private int bitShift

numBands

private int numBands

colorType

private int colorType

bpp

private int bpp

skipAlpha

private boolean skipAlpha

compressGray

private boolean compressGray

interlace

private boolean interlace

redPalette

private byte[] redPalette

greenPalette

private byte[] greenPalette

bluePalette

private byte[] bluePalette

alphaPalette

private byte[] alphaPalette

dataOutput

private DataOutputStream dataOutput

prevRow

private byte[] prevRow

currRow

private byte[] currRow

filteredRows

private byte[][] filteredRows

SRGB_CHROMA

private static final float[] SRGB_CHROMA

Constructor Details

PNGImageEncoder

public PNGImageEncoder(OutputStream output,
 PNGEncodeParam param)

Method Details

writeMagic

private void writeMagic()
                 throws IOException

Throws:

IOException

writeIHDR

private void writeIHDR()
                throws IOException

Throws:

IOException

clamp

private static int clamp(int val,
 int maxValue)

encodePass

private void encodePass(OutputStream os,
 Raster ras,
 int xOffset,
 int yOffset,
 int xSkip,
 int ySkip)
                 throws IOException

Throws:

IOException

writeIDAT

private void writeIDAT()
                throws IOException

Throws:

IOException

writeIEND

private void writeIEND()
                throws IOException

Throws:

IOException

writeCHRM

private void writeCHRM()
                throws IOException

Throws:

IOException

writeGAMA

private void writeGAMA()
                throws IOException

Throws:

IOException

writeICCP

private void writeICCP()
                throws IOException

Throws:

IOException

writeSBIT

private void writeSBIT()
                throws IOException

Throws:

IOException

writeSRGB

private void writeSRGB()
                throws IOException

Throws:

IOException

writePLTE

private void writePLTE()
                throws IOException

Throws:

IOException

writeBKGD

private void writeBKGD()
                throws IOException

Throws:

IOException

writeHIST

private void writeHIST()
                throws IOException

Throws:

IOException

writeTRNS

private void writeTRNS()
                throws IOException

Throws:

IOException

writePHYS

private void writePHYS()
                throws IOException

Throws:

IOException

writeSPLT

private void writeSPLT()
                throws IOException

Throws:

IOException

writeTIME

private void writeTIME()
                throws IOException

Throws:

IOException

writeTEXT

private void writeTEXT()
                throws IOException

Throws:

IOException

writeZTXT

private void writeZTXT()
                throws IOException

Throws:

IOException

writePrivateChunks

private void writePrivateChunks()
                         throws IOException

Throws:

IOException

createGrayParam

private PNGEncodeParam.Gray createGrayParam(byte[] redPalette,
 byte[] greenPalette,
 byte[] bluePalette,
 byte[] alphaPalette)

Analyzes a set of palettes and determines if it can be expressed as a standard set of gray values, with zero or one values being fully transparent and the rest being fully opaque. If it is possible to express the data thusly, the method returns a suitable instance of PNGEncodeParam.Gray; otherwise it returns null.

encode

public void encode(RenderedImage im)
            throws IOException

This method encodes a RenderedImage into PNG. The stream into which the PNG is dumped is not closed at the end of the operation, this should be done if needed by the caller of this method.

Specified by:

encode in interface ImageEncoder

Specified by:

encode in class ImageEncoderImpl

Throws:

IOException