| java.lang.Object
 com.keypoint.PngEncoder
| PngEncoder | | public class PngEncoder (Code) | | 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
author:
J. David Eisenberg
version:
1.5, 19 Oct 2003
version:
CHANGES:
version:
--------
version:
19-Nov-2002 : CODING STYLE CHANGES ONLY (by David Gilbert for Object
version:
Refinery Limited);
version:
19-Sep-2003 : Fix for platforms using EBCDIC (contributed by Paulo Soares);
version:
19-Oct-2003 : Change private fields to protected fields so that
version:
PngEncoderB can inherit them (JDE)
version:
Fixed bug with calculation of nRows |
| Field Summary | |
| final public static boolean | ENCODE_ALPHA
Constant specifying that alpha channel should be encoded. | | final public static int | FILTER_LAST
Constants for filter (LAST). | | final public static int | FILTER_NONE
Constants for filter (NONE). | | final public static int | FILTER_SUB
Constants for filter (SUB). | | final public static int | FILTER_UP
Constants for filter (UP). | | final protected static byte[] | IDAT
IDAT tag. | | final protected static byte[] | IEND
IEND tag. | | final protected static byte[] | IHDR
IHDR tag. | | final public static boolean | NO_ALPHA
Constant specifying that alpha channel should not be encoded. | | final protected static byte[] | PHYS
| | protected int | bytePos
The byte position. | | protected int | bytesPerPixel
The bytes-per-pixel. | | protected int | compressionLevel
The compression level (1 = best speed, 9 = best compression,
0 = no compression). | | protected CRC32 | crc
CRC. | | protected long | crcValue
The CRC value. | | protected boolean | encodeAlpha
| | protected int | filter
The filter type. | | protected int | height
The height. | | protected Image | image
The image. | | protected byte[] | leftBytes
The left bytes. | | protected int | maxPos
The maximum position. | | protected byte[] | pngBytes
The png bytes. | | protected byte[] | priorRow
The prior row. | | protected int | width
The width. |
| Constructor Summary | |
| public | PngEncoder()
Class constructor. | | public | PngEncoder(Image image)
Class constructor specifying Image to encode, with no alpha channel
encoding. | | public | PngEncoder(Image image, boolean encodeAlpha)
Class constructor specifying Image to encode, and whether to encode
alpha. | | public | PngEncoder(Image image, boolean encodeAlpha, int whichFilter)
Class constructor specifying Image to encode, whether to encode alpha,
and filter to use. | | 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. |
| Method Summary | |
| protected void | filterSub(byte[] pixels, int startPos, int width)
Perform "sub" filtering on the given row.
Uses temporary array leftBytes to store the original values
of the previous pixels. | | protected void | filterUp(byte[] pixels, int startPos, int width)
Perform "up" filtering on the given row. | | public int | getCompressionLevel()
Retrieve compression level. | | public boolean | getEncodeAlpha()
Retrieve alpha encoding status. | | public int | getFilter()
Retrieve filtering scheme. | | public Image | getImage()
Returns the image to be encoded. | | public int | getXDpi()
Get the DPI for the X axis. | | public int | getYDpi()
Get the DPI for the Y axis. | | 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. | | public byte[] | pngEncode()
Creates an array of bytes that is the PNG equivalent of the current
image. | | protected byte[] | resizeByteArray(byte[] array, int newLength)
Increase or decrease the length of a byte array.
Parameters:
array - The original array.
Parameters:
newLength - The length you wish the new array to have. | | public void | setCompressionLevel(int level)
Set the compression level to use. | | public void | setDpi(int xDpi, int yDpi)
Set the DPI resolution. | | public void | setEncodeAlpha(boolean encodeAlpha)
Set the alpha encoding on or off. | | public void | setFilter(int whichFilter)
Set the filter to use. | | public void | setImage(Image image)
Set the image to be encoded. | | public void | setXDpi(int xDpi)
Set the DPI for the X axis. | | public void | setYDpi(int yDpi)
Set the DPI for the Y axis. | | protected int | writeByte(int b, int offset)
Write a single byte into the pngBytes array at a given position.
Parameters:
b - The integer to be written into pngBytes.
Parameters:
offset - The starting point to write to. | | protected int | writeBytes(byte[] data, int offset)
Write an array of bytes into the pngBytes array.
Note: This routine has the side effect of updating
maxPos, the largest element written in the array.
The array is resized by 1000 bytes or the length
of the data to be written, whichever is larger.
Parameters:
data - The data to be written into pngBytes.
Parameters:
offset - The starting point to write to. | | 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.
This will write one or more PNG "IDAT" chunks. | | protected int | writeInt2(int n, int offset)
Write a two-byte integer into the pngBytes array at a given position.
Parameters:
n - The integer to be written into pngBytes.
Parameters:
offset - The starting point to write to. | | protected int | writeInt4(int n, int offset)
Write a four-byte integer into the pngBytes array at a given position.
Parameters:
n - The integer to be written into pngBytes.
Parameters:
offset - The starting point to write to. | | protected void | writeResolution()
Write a PNG "pHYs" chunk into the pngBytes array. |
| ENCODE_ALPHA | | final public static boolean ENCODE_ALPHA(Code) | | Constant specifying that alpha channel should be encoded.
|
| FILTER_LAST | | final public static int FILTER_LAST(Code) | | Constants for filter (LAST).
|
| FILTER_NONE | | final public static int FILTER_NONE(Code) | | Constants for filter (NONE).
|
| FILTER_SUB | | final public static int FILTER_SUB(Code) | | Constants for filter (SUB).
|
| FILTER_UP | | final public static int FILTER_UP(Code) | | Constants for filter (UP).
|
| IDAT | | final protected static byte[] IDAT(Code) | | IDAT tag.
|
| IEND | | final protected static byte[] IEND(Code) | | IEND tag.
|
| IHDR | | final protected static byte[] IHDR(Code) | | IHDR tag.
|
| NO_ALPHA | | final public static boolean NO_ALPHA(Code) | | Constant specifying that alpha channel should not be encoded.
|
| PHYS | | final protected static byte[] PHYS(Code) | | |
| bytePos | | protected int bytePos(Code) | | The byte position.
|
| bytesPerPixel | | protected int bytesPerPixel(Code) | | The bytes-per-pixel.
|
| compressionLevel | | protected int compressionLevel(Code) | | The compression level (1 = best speed, 9 = best compression,
0 = no compression).
|
| crcValue | | protected long crcValue(Code) | | The CRC value.
|
| encodeAlpha | | protected boolean encodeAlpha(Code) | | Encode alpha?
|
| filter | | protected int filter(Code) | | The filter type.
|
| height | | protected int height(Code) | | The height.
|
| leftBytes | | protected byte[] leftBytes(Code) | | The left bytes.
|
| maxPos | | protected int maxPos(Code) | | The maximum position.
|
| pngBytes | | protected byte[] pngBytes(Code) | | The png bytes.
|
| priorRow | | protected byte[] priorRow(Code) | | The prior row.
|
| width | | protected int width(Code) | | The width.
|
| PngEncoder | | public PngEncoder()(Code) | | Class constructor.
|
| PngEncoder | | public PngEncoder(Image image)(Code) | | 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)(Code) | | Class constructor specifying Image to encode, and whether to encode
alpha.
Parameters:
image - A Java Image object which uses the DirectColorModel
Parameters:
encodeAlpha - Encode the alpha channel? false=no; true=yes
See Also: java.awt.Image |
| PngEncoder | | public PngEncoder(Image image, boolean encodeAlpha, int whichFilter)(Code) | | Class constructor specifying Image to encode, whether to encode alpha,
and filter to use.
Parameters:
image - A Java Image object which uses the DirectColorModel
Parameters:
encodeAlpha - Encode the alpha channel? false=no; true=yes
Parameters:
whichFilter - 0=none, 1=sub, 2=up
See Also: java.awt.Image |
| PngEncoder | | public PngEncoder(Image image, boolean encodeAlpha, int whichFilter, int compLevel)(Code) | | Class constructor specifying Image source to encode, whether to encode
alpha, filter to use, and compression level.
Parameters:
image - A Java Image object
Parameters:
encodeAlpha - Encode the alpha channel? false=no; true=yes
Parameters:
whichFilter - 0=none, 1=sub, 2=up
Parameters:
compLevel - 0..9 (1 = best speed, 9 = best compression, 0 = no compression)
See Also: java.awt.Image |
| filterSub | | protected void filterSub(byte[] pixels, int startPos, int width)(Code) | | Perform "sub" filtering on the given row.
Uses temporary array leftBytes to store the original values
of the previous pixels. The array is 16 bytes long, which
will easily hold two-byte samples plus two-byte alpha.
Parameters:
pixels - The array holding the scan lines being built
Parameters:
startPos - Starting position within pixels of bytes to be filtered.
Parameters:
width - Width of a scanline in pixels. |
| filterUp | | protected void filterUp(byte[] pixels, int startPos, int width)(Code) | | Perform "up" filtering on the given row.
Side effect: refills the prior row with current row
Parameters:
pixels - The array holding the scan lines being built
Parameters:
startPos - Starting position within pixels of bytes to be filtered.
Parameters:
width - Width of a scanline in pixels. |
| getCompressionLevel | | public int getCompressionLevel()(Code) | | Retrieve compression level.
int (1 = best speed, 9 = best compression, 0 = no compression) |
| getEncodeAlpha | | public boolean getEncodeAlpha()(Code) | | Retrieve alpha encoding status.
boolean false=no, true=yes |
| getFilter | | public int getFilter()(Code) | | Retrieve filtering scheme.
int (see constant list) |
| getImage | | public Image getImage()(Code) | | Returns the image to be encoded.
|
| getXDpi | | public int getXDpi()(Code) | | Get the DPI for the X axis.
The number of dots per inch |
| getYDpi | | public int getYDpi()(Code) | | Get the DPI for the Y axis.
The number of dots per inch |
| pngEncode | | public byte[] pngEncode(boolean encodeAlpha)(Code) | | 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 an array of bytes, or null if there was a problem |
| pngEncode | | public byte[] pngEncode()(Code) | | Creates an array of bytes that is the PNG equivalent of the current
image. Alpha encoding is determined by its setting in the constructor.
an array of bytes, or null if there was a problem |
| resizeByteArray | | protected byte[] resizeByteArray(byte[] array, int newLength)(Code) | | Increase or decrease the length of a byte array.
Parameters:
array - The original array.
Parameters:
newLength - The length you wish the new array to have. Array of newly desired length. If shorter than theoriginal, the trailing elements are truncated. |
| setCompressionLevel | | public void setCompressionLevel(int level)(Code) | | 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)(Code) | | Set the DPI resolution.
Parameters:
xDpi - The number of dots per inch for the X axis.
Parameters:
yDpi - The number of dots per inch for the Y axis. |
| setEncodeAlpha | | public void setEncodeAlpha(boolean encodeAlpha)(Code) | | Set the alpha encoding on or off.
Parameters:
encodeAlpha - false=no, true=yes |
| setFilter | | public void setFilter(int whichFilter)(Code) | | Set the filter to use.
Parameters:
whichFilter - from constant list |
| setXDpi | | public void setXDpi(int xDpi)(Code) | | Set the DPI for the X axis.
Parameters:
xDpi - The number of dots per inch |
| setYDpi | | public void setYDpi(int yDpi)(Code) | | Set the DPI for the Y axis.
Parameters:
yDpi - The number of dots per inch |
| writeByte | | protected int writeByte(int b, int offset)(Code) | | Write a single byte into the pngBytes array at a given position.
Parameters:
b - The integer to be written into pngBytes.
Parameters:
offset - The starting point to write to. The next place to be written to in the pngBytes array. |
| writeBytes | | protected int writeBytes(byte[] data, int offset)(Code) | | Write an array of bytes into the pngBytes array.
Note: This routine has the side effect of updating
maxPos, the largest element written in the array.
The array is resized by 1000 bytes or the length
of the data to be written, whichever is larger.
Parameters:
data - The data to be written into pngBytes.
Parameters:
offset - The starting point to write to. The next place to be written to in the pngBytes array. |
| writeBytes | | protected int writeBytes(byte[] data, int nBytes, int offset)(Code) | | Write an array of bytes into the pngBytes array, specifying number of
bytes to write. Note: This routine has the side effect of updating
maxPos, the largest element written in the array.
The array is resized by 1000 bytes or the length
of the data to be written, whichever is larger.
Parameters:
data - The data to be written into pngBytes.
Parameters:
nBytes - The number of bytes to be written.
Parameters:
offset - The starting point to write to. The next place to be written to in the pngBytes array. |
| writeEnd | | protected void writeEnd()(Code) | | Write a PNG "IEND" chunk into the pngBytes array.
|
| writeHeader | | protected void writeHeader()(Code) | | Write a PNG "IHDR" chunk into the pngBytes array.
|
| writeImageData | | protected boolean writeImageData()(Code) | | 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.
true if no errors; false if error grabbing pixels |
| writeInt2 | | protected int writeInt2(int n, int offset)(Code) | | Write a two-byte integer into the pngBytes array at a given position.
Parameters:
n - The integer to be written into pngBytes.
Parameters:
offset - The starting point to write to. The next place to be written to in the pngBytes array. |
| writeInt4 | | protected int writeInt4(int n, int offset)(Code) | | Write a four-byte integer into the pngBytes array at a given position.
Parameters:
n - The integer to be written into pngBytes.
Parameters:
offset - The starting point to write to. The next place to be written to in the pngBytes array. |
| writeResolution | | protected void writeResolution()(Code) | | Write a PNG "pHYs" chunk into the pngBytes array.
|
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