com.keypoint
Class PngEncoderB

java.lang.Object
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  +--com.keypoint.PngEncoder
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        +--com.keypoint.PngEncoderB

public class PngEncoderB

extends PngEncoder

PngEncoderB takes a Java BufferedImage object and creates a byte string which can be saved as a PNG file. The encoder will accept BufferedImages with eight-bit samples or 4-byte ARGB samples.

There is also code to handle 4-byte samples returned as one int per pixel, but that has not been tested.

Thanks to Jay Denny at KeyPoint Software http://www.keypoint.com/ who let me develop this code on company time.

You may contact me with (probably very-much-needed) improvements, comments, and bug fixes at:

david@catcode.com

This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA A copy of the GNU LGPL may be found at http://www.gnu.org/copyleft/lesser.html

Field Summary

protected java.awt.image.BufferedImage	image
protected int	tType
protected java.awt.image.WritableRaster	wRaster

Fields inherited from class com.keypoint.PngEncoder

bytePos, bytesPerPixel, compressionLevel, crc, crcValue, ENCODE_ALPHA, encodeAlpha, filter, FILTER_LAST, FILTER_NONE, FILTER_SUB, FILTER_UP, height, IDAT, IEND, IHDR, leftBytes, maxPos, NO_ALPHA, pngBytes, priorRow, width

Constructor Summary

PngEncoderB()
Class constructor

PngEncoderB(java.awt.image.BufferedImage image)
Class constructor specifying BufferedImage to encode, with no alpha channel encoding.

PngEncoderB(java.awt.image.BufferedImage image, boolean encodeAlpha)
Class constructor specifying BufferedImage to encode, and whether to encode alpha.

PngEncoderB(java.awt.image.BufferedImage image, boolean encodeAlpha, int whichFilter)
Class constructor specifying BufferedImage to encode, whether to encode alpha, and filter to use.

PngEncoderB(java.awt.image.BufferedImage image, boolean encodeAlpha, int whichFilter, int compLevel)
Class constructor specifying BufferedImage source to encode, whether to encode alpha, filter to use, and compression level

Method Summary

protected boolean	establishStorageInfo() Get and set variables that determine how picture is stored.
byte[]	pngEncode() Creates an array of bytes that is the PNG equivalent of the current image.
byte[]	pngEncode(boolean encodeAlpha) Creates an array of bytes that is the PNG equivalent of the current image, specifying whether to encode alpha or not.
void	setImage(java.awt.image.BufferedImage image) Set the BufferedImage to be encoded
protected void	writeHeader() Write a PNG "IHDR" chunk into the pngBytes array.
protected boolean	writeImageData() Write the image data into the pngBytes array.
protected void	writePalette(java.awt.image.IndexColorModel icm)

Methods inherited from class com.keypoint.PngEncoder

filterSub, filterUp, getCompressionLevel, getEncodeAlpha, getFilter, resizeByteArray, setCompressionLevel, setEncodeAlpha, setFilter, setImage, writeByte, writeBytes, writeBytes, writeEnd, writeInt2, writeInt4

Methods inherited from class java.lang.Object

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

Field Detail

image

protected java.awt.image.BufferedImage image

wRaster

protected java.awt.image.WritableRaster wRaster

tType

protected int tType

Constructor Detail

PngEncoderB

public PngEncoderB()

Class constructor

PngEncoderB

public PngEncoderB(java.awt.image.BufferedImage image)

Class constructor specifying BufferedImage to encode, with no alpha channel encoding.

Parameters:

image - A Java BufferedImage object

PngEncoderB

public PngEncoderB(java.awt.image.BufferedImage image,
                   boolean encodeAlpha)

Class constructor specifying BufferedImage to encode, and whether to encode alpha.

Parameters:

image - A Java BufferedImage object

encodeAlpha - Encode the alpha channel? false=no; true=yes

PngEncoderB

public PngEncoderB(java.awt.image.BufferedImage image,
                   boolean encodeAlpha,
                   int whichFilter)

Class constructor specifying BufferedImage to encode, whether to encode alpha, and filter to use.

Parameters:

image - A Java BufferedImage object

encodeAlpha - Encode the alpha channel? false=no; true=yes

whichFilter - 0=none, 1=sub, 2=up

PngEncoderB

public PngEncoderB(java.awt.image.BufferedImage image,
                   boolean encodeAlpha,
                   int whichFilter,
                   int compLevel)

Class constructor specifying BufferedImage source to encode, whether to encode alpha, filter to use, and compression level

Parameters:

image - A Java BufferedImage object

encodeAlpha - Encode the alpha channel? false=no; true=yes

whichFilter - 0=none, 1=sub, 2=up

compLevel - 0..9

Method Detail

setImage

public void setImage(java.awt.image.BufferedImage image)

Set the BufferedImage to be encoded

pngEncode

public byte[] pngEncode(boolean encodeAlpha)

Creates an array of bytes that is the PNG equivalent of the current image, specifying whether to encode alpha or not.

Overrides:

pngEncode in class PngEncoder

Parameters:

encodeAlpha - boolean false=no alpha, true=encode alpha

Returns:

an array of bytes, or null if there was a problem

pngEncode

public byte[] pngEncode()

Creates an array of bytes that is the PNG equivalent of the current image. Alpha encoding is determined by its setting in the constructor.

Overrides:

pngEncode in class PngEncoder

Returns:

an array of bytes, or null if there was a problem

establishStorageInfo

protected boolean establishStorageInfo()

Get and set variables that determine how picture is stored. Retrieves the writable raster of the buffered image, as well its transfer type. Sets number of output bytes per pixel, and, if only eight-bit bytes, turns off alpha encoding.

Returns:

true if 1-byte or 4-byte data, false otherwise

writeHeader

protected void writeHeader()

Write a PNG "IHDR" chunk into the pngBytes array.

Overrides:

writeHeader in class PngEncoder

writePalette

protected void writePalette(java.awt.image.IndexColorModel icm)

writeImageData

protected boolean writeImageData()

Write the image data into the pngBytes array. This will write one or more PNG "IDAT" chunks. In order to conserve memory, this method grabs as many rows as will fit into 32K bytes, or the whole image; whichever is less.

Overrides:

writeImageData in class PngEncoder

Returns:

true if no errors; false if error grabbing pixels