org.pentaho.reporting.libraries.base.util

Class PngEncoder

public class PngEncoder extends Object implements ImageEncoder

PngEncoder takes a Java Image object and creates a byte string which can be saved as a PNG file. The Image is presumed to use the DirectColorModel.

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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. A copy of the GNU LGPL may be found at http://www.gnu.org/copyleft/lesser.html

Version: 1.5, 19 Oct 2003

CHANGES: -------- 19-Nov-2002 : CODING STYLE CHANGES ONLY (by David Gilbert for Object Refinery Limited); 19-Sep-2003 : Fix for platforms using EBCDIC (contributed by Paulo Soares); 19-Oct-2003 : Change private fields to protected fields so that PngEncoderB can inherit them (JDE) Fixed bug with calculation of nRows

Author: J. David Eisenberg

Field Summary
static booleanENCODE_ALPHA
Constant specifying that alpha channel should be encoded.
static intFILTER_LAST
Constants for filter (LAST).
static intFILTER_NONE
Constants for filter (NONE).
static intFILTER_SUB
Constants for filter (SUB).
static intFILTER_UP
Constants for filter (UP).
static booleanNO_ALPHA
Constant specifying that alpha channel should not be encoded.
Constructor Summary
PngEncoder()
Class constructor.
PngEncoder(Image image)
Class constructor specifying Image to encode, with no alpha channel encoding.
PngEncoder(Image image, boolean encodeAlpha)
Class constructor specifying Image to encode, and whether to encode alpha.
PngEncoder(Image image, boolean encodeAlpha, int whichFilter)
Class constructor specifying Image to encode, whether to encode alpha, and filter to use.
PngEncoder(Image image, boolean encodeAlpha, int whichFilter, int compLevel)
Class constructor specifying Image source to encode, whether to encode alpha, filter to use, and compression level.
Method Summary
voidencodeImage(Image image, OutputStream outputStream, float quality, boolean encodeAlpha)
intgetCompressionLevel()
Retrieve compression level.
booleangetEncodeAlpha()
Retrieve alpha encoding status.
intgetFilter()
Retrieve filtering scheme.
ImagegetImage()
Returns the image to be encoded.
StringgetMimeType()
intgetXDpi()
Get the DPI for the X axis.
intgetYDpi()
Get the DPI for the Y axis.
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.
byte[]pngEncode()
Creates an array of bytes that is the PNG equivalent of the current image.
voidsetCompressionLevel(int level)
Set the compression level to use.
voidsetDpi(int xDpi, int yDpi)
Set the DPI resolution.
voidsetEncodeAlpha(boolean encodeAlpha)
Set the alpha encoding on or off.
voidsetFilter(int whichFilter)
Set the filter to use.
voidsetImage(Image image)
Set the image to be encoded.
voidsetXDpi(int xDpi)
Set the DPI for the X axis.
voidsetYDpi(int yDpi)
Set the DPI for the Y axis.

Field Detail

ENCODE_ALPHA

public static final boolean ENCODE_ALPHA
Constant specifying that alpha channel should be encoded.

FILTER_LAST

public static final int FILTER_LAST
Constants for filter (LAST).

FILTER_NONE

public static final int FILTER_NONE
Constants for filter (NONE).

FILTER_SUB

public static final int FILTER_SUB
Constants for filter (SUB).

FILTER_UP

public static final int FILTER_UP
Constants for filter (UP).

NO_ALPHA

public static final boolean NO_ALPHA
Constant specifying that alpha channel should not be encoded.

Constructor Detail

PngEncoder

public PngEncoder()
Class constructor.

PngEncoder

public PngEncoder(Image image)
Class constructor specifying Image to encode, with no alpha channel encoding.

Parameters: image A Java Image object which uses the DirectColorModel

See Also: java.awt.Image

PngEncoder

public PngEncoder(Image image, boolean encodeAlpha)
Class constructor specifying Image to encode, and whether to encode alpha.

Parameters: image A Java Image object which uses the DirectColorModel encodeAlpha Encode the alpha channel? false=no; true=yes

See Also: java.awt.Image

PngEncoder

public PngEncoder(Image image, boolean encodeAlpha, int whichFilter)
Class constructor specifying Image to encode, whether to encode alpha, and filter to use.

Parameters: image A Java Image object which uses the DirectColorModel encodeAlpha Encode the alpha channel? false=no; true=yes whichFilter 0=none, 1=sub, 2=up

See Also: java.awt.Image

PngEncoder

public PngEncoder(Image image, boolean encodeAlpha, int whichFilter, int compLevel)
Class constructor specifying Image source to encode, whether to encode alpha, filter to use, and compression level.

Parameters: image A Java Image object encodeAlpha Encode the alpha channel? false=no; true=yes whichFilter 0=none, 1=sub, 2=up compLevel 0..9 (1 = best speed, 9 = best compression, 0 = no compression)

See Also: java.awt.Image

Method Detail

encodeImage

public void encodeImage(Image image, OutputStream outputStream, float quality, boolean encodeAlpha)

getCompressionLevel

public int getCompressionLevel()
Retrieve compression level.

Returns: int (1 = best speed, 9 = best compression, 0 = no compression)

getEncodeAlpha

public boolean getEncodeAlpha()
Retrieve alpha encoding status.

Returns: boolean false=no, true=yes

getFilter

public int getFilter()
Retrieve filtering scheme.

Returns: int (see constant list)

getImage

public Image getImage()
Returns the image to be encoded.

Returns: the image to be encoded.

getMimeType

public String getMimeType()

getXDpi

public int getXDpi()
Get the DPI for the X axis.

Returns: The number of dots per inch

getYDpi

public int getYDpi()
Get the DPI for the Y axis.

Returns: The number of dots per inch

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.

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.

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

setCompressionLevel

public void setCompressionLevel(int level)
Set the compression level to use.

Parameters: level the compression level (1 = best speed, 9 = best compression, 0 = no compression)

setDpi

public void setDpi(int xDpi, int yDpi)
Set the DPI resolution.

Parameters: xDpi The number of dots per inch for the X axis. yDpi The number of dots per inch for the Y axis.

setEncodeAlpha

public void setEncodeAlpha(boolean encodeAlpha)
Set the alpha encoding on or off.

Parameters: encodeAlpha false=no, true=yes

setFilter

public void setFilter(int whichFilter)
Set the filter to use.

Parameters: whichFilter from constant list

setImage

public void setImage(Image image)
Set the image to be encoded.

Parameters: image A Java Image object which uses the DirectColorModel

See Also: java.awt.Image java.awt.image.DirectColorModel

setXDpi

public void setXDpi(int xDpi)
Set the DPI for the X axis.

Parameters: xDpi The number of dots per inch

setYDpi

public void setYDpi(int yDpi)
Set the DPI for the Y axis.

Parameters: yDpi The number of dots per inch