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java.lang.Object | +--com.keypoint.PngEncoder
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., 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 | |
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static boolean |
ENCODE_ALPHA
Constant specifying that alpha channel should be encoded. |
static int |
FILTER_LAST
Constants for filter (LAST) |
static int |
FILTER_NONE
Constants for filter (NONE) |
static int |
FILTER_SUB
Constants for filter (SUB) |
static int |
FILTER_UP
Constants for filter (UP) |
static boolean |
NO_ALPHA
Constant specifying that alpha channel should not be encoded. |
Constructor Summary | |
---|---|
PngEncoder()
Class constructor |
|
PngEncoder(java.awt.Image image)
Class constructor specifying Image to encode, with no alpha channel encoding. |
|
PngEncoder(java.awt.Image image,
boolean encodeAlpha)
Class constructor specifying Image to encode, and whether to encode alpha. |
|
PngEncoder(java.awt.Image image,
boolean encodeAlpha,
int whichFilter)
Class constructor specifying Image to encode, whether to encode alpha, and filter to use. |
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PngEncoder(java.awt.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 | |
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protected void |
filterSub(byte[] pixels,
int startPos,
int width)
Perform "sub" filtering on the given row. |
protected void |
filterUp(byte[] pixels,
int startPos,
int width)
Perform "up" filtering on the given row. |
int |
getCompressionLevel()
Retrieve compression level |
boolean |
getEncodeAlpha()
Retrieve alpha encoding status. |
int |
getFilter()
Retrieve filtering scheme |
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. |
protected byte[] |
resizeByteArray(byte[] array,
int newLength)
Increase or decrease the length of a byte array. |
void |
setCompressionLevel(int level)
Set the compression level to use |
void |
setEncodeAlpha(boolean encodeAlpha)
Set the alpha encoding on or off. |
void |
setFilter(int whichFilter)
Set the filter to use |
void |
setImage(java.awt.Image image)
Set the image to be encoded |
protected int |
writeByte(int b,
int offset)
Write a single byte into the pngBytes array at a given position. |
protected int |
writeBytes(byte[] data,
int offset)
Write an array of bytes into the pngBytes array. |
protected int |
writeBytes(byte[] data,
int nBytes,
int offset)
Write an array of bytes into the pngBytes array, specifying number of bytes to write. |
protected void |
writeEnd()
Write a PNG "IEND" chunk into the pngBytes array. |
protected void |
writeHeader()
Write a PNG "IHDR" chunk into the pngBytes array. |
protected boolean |
writeImageData()
Write the image data into the pngBytes array. |
protected int |
writeInt2(int n,
int offset)
Write a two-byte integer into the pngBytes array at a given position. |
protected int |
writeInt4(int n,
int offset)
Write a four-byte integer into the pngBytes array at a given position. |
protected int |
writeString(java.lang.String s,
int offset)
Write a string into the pngBytes array at a given position. |
Methods inherited from class java.lang.Object |
---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
public static final boolean ENCODE_ALPHA
public static final boolean NO_ALPHA
public static final int FILTER_NONE
public static final int FILTER_SUB
public static final int FILTER_UP
public static final int FILTER_LAST
Constructor Detail |
public PngEncoder()
public PngEncoder(java.awt.Image image)
image
- A Java Image object which uses the DirectColorModelImage
public PngEncoder(java.awt.Image image, boolean encodeAlpha)
image
- A Java Image object which uses the DirectColorModelencodeAlpha
- Encode the alpha channel? false=no; true=yesImage
public PngEncoder(java.awt.Image image, boolean encodeAlpha, int whichFilter)
image
- A Java Image object which uses the DirectColorModelencodeAlpha
- Encode the alpha channel? false=no; true=yeswhichFilter
- 0=none, 1=sub, 2=upImage
public PngEncoder(java.awt.Image image, boolean encodeAlpha, int whichFilter, int compLevel)
image
- A Java Image objectencodeAlpha
- Encode the alpha channel? false=no; true=yeswhichFilter
- 0=none, 1=sub, 2=upcompLevel
- 0..9Image
Method Detail |
public void setImage(java.awt.Image image)
image
- A Java Image object which uses the DirectColorModelImage
,
DirectColorModel
public byte[] pngEncode(boolean encodeAlpha)
encodeAlpha
- boolean false=no alpha, true=encode alpha
public byte[] pngEncode()
public void setEncodeAlpha(boolean encodeAlpha)
encodeAlpha
- false=no, true=yespublic boolean getEncodeAlpha()
public void setFilter(int whichFilter)
whichFilter
- from constant listpublic int getFilter()
public void setCompressionLevel(int level)
level
- 0 through 9public int getCompressionLevel()
protected byte[] resizeByteArray(byte[] array, int newLength)
array
- The original array.newLength
- The length you wish the new array to have.
protected int writeBytes(byte[] data, int offset)
data
- The data to be written into pngBytes.offset
- The starting point to write to.
protected int writeBytes(byte[] data, int nBytes, int offset)
data
- The data to be written into pngBytes.nBytes
- The number of bytes to be written.offset
- The starting point to write to.
protected int writeInt2(int n, int offset)
n
- The integer to be written into pngBytes.offset
- The starting point to write to.
protected int writeInt4(int n, int offset)
n
- The integer to be written into pngBytes.offset
- The starting point to write to.
protected int writeByte(int b, int offset)
b
- The integer to be written into pngBytes.offset
- The starting point to write to.
protected int writeString(java.lang.String s, int offset)
s
- The string to be written into pngBytes.offset
- The starting point to write to.
String.getBytes()
protected void writeHeader()
protected void filterSub(byte[] pixels, int startPos, int width)
pixels
- The array holding the scan lines being builtstartPos
- Starting position within pixels of bytes to be filtered.width
- Width of a scanline in pixels.protected void filterUp(byte[] pixels, int startPos, int width)
pixels
- The array holding the scan lines being builtstartPos
- Starting position within pixels of bytes to be filtered.width
- Width of a scanline in pixels.protected boolean writeImageData()
protected void writeEnd()
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