echopointng.image.PngEncoder Maven / Gradle / Ivy
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package echopointng.image;
/*
* This file is part of the Echo Point Project. This project is a collection
* of Components that have extended the Echo Web Application Framework.
*
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*/
/*
* This LGPL code was written by J. David Eisenberg and can be found at :
*
* http://www.catcode.com/pngencoder/index.html
*
* v1.4 was incorporated as part of the EchoPoint library on 12/04/2003.
* v1.5 was incorporated as part of the EchoPoint library on 29/10/2003.
*
* Below is the original copyright notices as per the LGPL.
*
*/
/*
*
* 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:
*
* [email protected]
*
* 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,
*
* @author J. David Eisenberg
* @version 1.5, 19 Oct 2003
*
* CHANGES:
* --------
* com.keypoint.PngEncoder :
*
* 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
*
* com.keypoint.PngEncoderB :
*
* 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
* Added modifications for unsigned short images
* (contributed by Christian at xpogen.com)
*/
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.awt.image.DataBuffer;
import java.awt.image.ImageObserver;
import java.awt.image.IndexColorModel;
import java.awt.image.PixelGrabber;
import java.awt.image.WritableRaster;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.Serializable;
import java.util.zip.CRC32;
import java.util.zip.Deflater;
import java.util.zip.DeflaterOutputStream;
/**
* PngEncoder implements the ImageEncoder interface
* and hence can take a java.awt.Image object and encode it as a PNG
* output stream.
*
* The Image can have a DirectColorModel or an IndexColorModel.
*
* NOTE : While the Echo framework has a PNG encoder built in to it, it currently
* does not handle transparency correctly. Therefore this encoder has been
* provided.
*/
public class PngEncoder implements ImageEncoder, Serializable {
private transient InternalPngEncoderA encoder=null;
private boolean encodeAlpha = true;
/**
* Constructs a PngEncoder ready to start encoding, with the Alpha channel
* being encoded.
*/
public PngEncoder() {
encodeAlpha = true;
}
/**
* @see echopointng.image.ImageEncoder#encode(java.awt.Image, java.io.OutputStream)
*/
public void encode(Image image, OutputStream out) throws IOException {
if (encoder == null) {
//
// The newer B encoder will only take BufferedImage objects
// whereas the older A encoder takes Image objects.
//
if (image instanceof BufferedImage) {
encoder = new InternalPngEncoderB((BufferedImage) image);
} else {
encoder = new InternalPngEncoderA(image);
}
encoder.setEncodeAlpha(isEncodeAlpha());
} else {
encoder.setImage(image);
}
encoder.encode(out,true);
}
/**
* @see echopointng.image.ImageEncoder#getContentType()
*/
public String getContentType() {
return "image/png";
}
/**
* This returns true if the Alpha channel of the image will be encoded
*
* @return - true if the Alpha channel of the image will be encoded
*/
public boolean isEncodeAlpha() {
return encodeAlpha;
}
/**
* If this is set to true then the Alpha channel of the image will be encoded.
* By this value is true by default.
*
* @param b - true if the Alpha channel of the image is to be encoded
*/
public void setEncodeAlpha(boolean b) {
encodeAlpha = b;
}
}
/**
* The InternalPngEncoderB class is the original
* com.keypoint.PngEncoderB class. It has been renamed to fit
* under the echoPoint ImageEncoder scheme.
*
* @author J. David Eisenberg
* @version 1.5, 19 Oct 2003
*
*/
class InternalPngEncoderB extends InternalPngEncoderA
{
/** PLTE tag. */
private static final byte PLTE[] = { 80, 76, 84, 69 };
protected BufferedImage image;
protected WritableRaster wRaster;
protected int tType;
/**
* Class constructor
*
*/
public InternalPngEncoderB()
{
this( null, false, FILTER_NONE, 0 );
}
/**
* Class constructor specifying BufferedImage to encode, with no alpha channel encoding.
*
* @param image A Java BufferedImage object
*/
public InternalPngEncoderB( BufferedImage image )
{
this(image, false, FILTER_NONE, 0);
}
/**
* Class constructor specifying BufferedImage to encode, and whether to encode alpha.
*
* @param image A Java BufferedImage object
* @param encodeAlpha Encode the alpha channel? false=no; true=yes
*/
public InternalPngEncoderB( BufferedImage image, boolean encodeAlpha )
{
this( image, encodeAlpha, FILTER_NONE, 0 );
}
/**
* Class constructor specifying BufferedImage to encode, whether to encode alpha, and filter to use.
*
* @param image A Java BufferedImage object
* @param encodeAlpha Encode the alpha channel? false=no; true=yes
* @param whichFilter 0=none, 1=sub, 2=up
*/
public InternalPngEncoderB( BufferedImage image, boolean encodeAlpha,int whichFilter )
{
this( image, encodeAlpha, whichFilter, 0 );
}
/**
* Class constructor specifying BufferedImage source to encode, whether to encode alpha, filter to use, and compression level
*
* @param image A Java BufferedImage object
* @param encodeAlpha Encode the alpha channel? false=no; true=yes
* @param whichFilter 0=none, 1=sub, 2=up
* @param compLevel 0..9
*/
public InternalPngEncoderB( BufferedImage image, boolean encodeAlpha,int whichFilter, int compLevel )
{
this.image = image;
this.encodeAlpha = encodeAlpha;
setFilter( whichFilter );
if (compLevel >=0 && compLevel <=9)
{
this.compressionLevel = compLevel;
}
}
/**
* Set the BufferedImage to be encoded
*
* @param BufferedImage A Java BufferedImage object
*/
public void setImage( BufferedImage image )
{
this.image = image;
pngBytes = null;
}
/**
* Creates an array of bytes that is the PNG equivalent of the current image, specifying whether to encode alpha or not.
*
* @param encodeAlpha boolean false=no alpha, true=encode alpha
* @return an array of bytes, or null if there was a problem
*/
public byte[] pngEncode( boolean encodeAlpha )
{
byte[] pngIdBytes = { -119, 80, 78, 71, 13, 10, 26, 10 };
if (image == null)
{
System.err.println("pngEncode: image is null; returning null");
return null;
}
width = image.getWidth( null );
height = image.getHeight( null );
if (!establishStorageInfo())
{
System.err.println("pngEncode: cannot establish storage info");
return null;
}
/*
* start with an array that is big enough to hold all the pixels
* (plus filter bytes), and an extra 200 bytes for header info
*/
pngBytes = new byte[((width+1) * height * 3) + 200];
/*
* keep track of largest byte written to the array
*/
maxPos = 0;
bytePos = writeBytes( pngIdBytes, 0 );
// hdrPos = bytePos;
writeHeader();
// dataPos = bytePos;
if (writeImageData())
{
writeEnd();
pngBytes = resizeByteArray( pngBytes, maxPos );
}
else
{
System.err.println("pngEncode: writeImageData failed => null");
pngBytes = null;
}
return pngBytes;
}
/**
* Creates an array of bytes that is the PNG equivalent of the current image.
* Alpha encoding is determined by its setting in the constructor.
*
* @return an array of bytes, or null if there was a problem
*/
public byte[] pngEncode()
{
return pngEncode( encodeAlpha );
}
/**
*
* 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.
* @return true if 1-byte or 4-byte data, false otherwise
*/
protected boolean establishStorageInfo()
{
int dataBytes;
wRaster = image.getRaster();
dataBytes = wRaster.getNumDataElements();
tType = wRaster.getTransferType();
if (((tType == DataBuffer.TYPE_BYTE ) && (dataBytes == 4)) ||
((tType == DataBuffer.TYPE_INT ) && (dataBytes == 1)) ||
// on Win 2k/ME, tType == 1, dataBytes == 1
((tType == DataBuffer.TYPE_USHORT) && (dataBytes == 1)) )
{
bytesPerPixel = (encodeAlpha) ? 4 : 3;
}
else if ((tType == DataBuffer.TYPE_BYTE) && (dataBytes == 1))
{
bytesPerPixel = 1;
encodeAlpha = false; // one-byte samples
}
else
{
System.err.println("PNG encoder cannot establish storage info:");
System.err.println(" TransferType == " + tType );
System.err.println(" NumDataElements == " + dataBytes);
return false;
}
return true;
}
/**
* Write a PNG "IHDR" chunk into the pngBytes array.
*/
protected void writeHeader()
{
int startPos;
startPos = bytePos = writeInt4( 13, bytePos );
bytePos = writeBytes( IHDR, bytePos );
width = image.getWidth( null );
height = image.getHeight( null );
bytePos = writeInt4( width, bytePos );
bytePos = writeInt4( height, bytePos );
bytePos = writeByte( 8, bytePos ); // bit depth
if (bytesPerPixel != 1)
{
bytePos = writeByte( (encodeAlpha) ? 6 : 2, bytePos ); // direct model
}
else
{
bytePos = writeByte( 3, bytePos ); // indexed
}
bytePos = writeByte( 0, bytePos ); // compression method
bytePos = writeByte( 0, bytePos ); // filter method
bytePos = writeByte( 0, bytePos ); // no interlace
crc.reset();
crc.update( pngBytes, startPos, bytePos-startPos );
crcValue = crc.getValue();
bytePos = writeInt4( (int) crcValue, bytePos );
}
protected void writePalette( IndexColorModel icm )
{
byte[] redPal = new byte[256];
byte[] greenPal = new byte[256];
byte[] bluePal = new byte[256];
byte[] allPal = new byte[768];
int i;
icm.getReds( redPal );
icm.getGreens( greenPal );
icm.getBlues( bluePal );
for (i=0; i<256; i++)
{
allPal[i*3 ] = redPal[i];
allPal[i*3+1] = greenPal[i];
allPal[i*3+2] = bluePal[i];
}
bytePos = writeInt4( 768, bytePos );
bytePos = writeBytes( PLTE, bytePos );
crc.reset();
crc.update( PLTE );
bytePos = writeBytes( allPal, bytePos );
crc.update( allPal );
crcValue = crc.getValue();
bytePos = writeInt4( (int) crcValue, bytePos );
}
/**
* 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.
*
*
* @return true if no errors; false if error grabbing pixels
*/
protected boolean writeImageData()
{
int rowsLeft = height; // number of rows remaining to write
int startRow = 0; // starting row to process this time through
int nRows; // how many rows to grab at a time
byte[] scanLines; // the scan lines to be compressed
int scanPos; // where we are in the scan lines
int startPos; // where this line's actual pixels start (used for filtering)
int readPos; // position from which source pixels are read
byte[] compressedLines; // the resultant compressed lines
int nCompressed; // how big is the compressed area?
byte[] pixels; // storage area for byte-sized pixels
int[] iPixels; // storage area for int-sized pixels
short[] sPixels; // for Win 2000/ME ushort pixels
final int type = image.getType();
// TYPE_INT_RGB = 1
// TYPE_INT_ARGB = 2
// TYPE_INT_ARGB_PRE = 3
// TYPE_INT_BGR = 4
// TYPE_3BYTE_BGR = 5
// TYPE_4BYTE_ABGR = 6
// TYPE_4BYTE_ABGR_PRE = 7
// TYPE_BYTE_GRAY = 10
// TYPE_BYTE_BINARY = 12
// TYPE_BYTE_INDEXED = 13
// TYPE_USHORT_GRAY = 11
// TYPE_USHORT_565_RGB = 8
// TYPE_USHORT_555_RGB = 9
// TYPE_CUSTOM = 0.
Deflater scrunch = new Deflater( compressionLevel );
ByteArrayOutputStream outBytes =
new ByteArrayOutputStream(1024);
DeflaterOutputStream compBytes =
new DeflaterOutputStream( outBytes, scrunch );
if (bytesPerPixel == 1)
{
writePalette( (IndexColorModel) image.getColorModel() );
}
try
{
while (rowsLeft > 0)
{
nRows = Math.min( 32767 / (width*(bytesPerPixel+1)), rowsLeft );
nRows = Math.max( nRows, 1 );
/*
* Create a data chunk. scanLines adds "nRows" for
* the filter bytes.
*/
scanLines = new byte[width * nRows * bytesPerPixel + nRows];
if (filter == FILTER_SUB)
{
leftBytes = new byte[16];
}
if (filter == FILTER_UP)
{
priorRow = new byte[width*bytesPerPixel];
}
final Object data =
wRaster.getDataElements( 0, startRow, width, nRows, null );
pixels = null;
iPixels = null;
sPixels = null;
if (tType == DataBuffer.TYPE_BYTE)
{
pixels = (byte[]) data;
}
else if (tType == DataBuffer.TYPE_INT)
{
iPixels = (int[]) data;
}
else if (tType == DataBuffer.TYPE_USHORT)
{
sPixels = (short[]) data;
}
scanPos = 0;
readPos = 0;
startPos = 1;
for (int i=0; i> 8) & 0xf8);
scanLines[scanPos++] = (byte) ((pxl >> 2) & 0xfc);
} else { // assume USHORT_555_RGB
scanLines[scanPos++] = (byte) ((pxl >> 7) & 0xf8);
scanLines[scanPos++] = (byte) ((pxl >> 2) & 0xf8);
}
scanLines[scanPos++] = (byte) ((pxl << 3) & 0xf8);
}
else // assume tType INT and type RGB or ARGB
{
int pxl = iPixels[readPos++];
scanLines[scanPos++] = (byte) ((pxl >> 16) & 0xff);
scanLines[scanPos++] = (byte) ((pxl >> 8) & 0xff);
scanLines[scanPos++] = (byte) ((pxl ) & 0xff);
if (encodeAlpha) {
scanLines[scanPos++] = (byte) ((pxl >> 24) & 0xff);
}
}
if ((i % width == width-1) && (filter != FILTER_NONE))
{
if (filter == FILTER_SUB)
{
filterSub( scanLines, startPos, width );
}
if (filter == FILTER_UP)
{
filterUp( scanLines, startPos, width );
}
}
}
/*
* Write these lines to the output area
*/
compBytes.write( scanLines, 0, scanPos );
startRow += nRows;
rowsLeft -= nRows;
}
compBytes.close();
/*
* Write the compressed bytes
*/
compressedLines = outBytes.toByteArray();
nCompressed = compressedLines.length;
crc.reset();
bytePos = writeInt4( nCompressed, bytePos );
bytePos = writeBytes( IDAT, bytePos );
crc.update( IDAT );
bytePos = writeBytes( compressedLines, nCompressed, bytePos );
crc.update( compressedLines, 0, nCompressed );
crcValue = crc.getValue();
bytePos = writeInt4( (int) crcValue, bytePos );
scrunch.finish();
return true;
}
catch (IOException e)
{
System.err.println( e.toString());
return false;
}
}
}
/**
* The InternalPngEncoderA class is the original
* com.keypoint.PngEncoder class. It has been renamed to fit
* under the echoPoint ImageEncoder scheme.
*
* @author J. David Eisenberg
* @version 1.5, 19 Oct 2003
*
*/
class InternalPngEncoderA extends Object {
/** Constant specifying that alpha channel should be encoded. */
public static final boolean ENCODE_ALPHA = true;
/** Constant specifying that alpha channel should not be encoded. */
public static final boolean NO_ALPHA = false;
/** Constants for filter (NONE) */
public static final int FILTER_NONE = 0;
/** Constants for filter (SUB) */
public static final int FILTER_SUB = 1;
/** Constants for filter (UP) */
public static final int FILTER_UP = 2;
/** Constants for filter (LAST) */
public static final int FILTER_LAST = 2;
/** IHDR tag. */
protected static final byte IHDR[] = {73, 72, 68, 82};
/** IDAT tag. */
protected static final byte IDAT[] = {73, 68, 65, 84};
/** IEND tag. */
protected static final byte IEND[] = {73, 69, 78, 68};
/** The png bytes. */
protected byte[] pngBytes;
/** The prior row. */
protected byte[] priorRow;
/** The left bytes. */
protected byte[] leftBytes;
/** The image. */
protected Image image;
/** The width. */
protected int width, height;
/** The byte position. */
protected int bytePos, maxPos;
/** CRC. */
protected CRC32 crc = new CRC32();
/** The CRC value. */
protected long crcValue;
/** Encode alpha? */
protected boolean encodeAlpha;
/** The filter type. */
protected int filter;
/** The bytes-per-pixel. */
protected int bytesPerPixel;
/** The compression level. */
protected int compressionLevel;
/**
* Class constructor
*/
public InternalPngEncoderA() {
this(null, false, FILTER_NONE, 0);
}
/**
* Class constructor specifying Image to encode, with no alpha channel encoding.
*
* @param image A Java Image object which uses the DirectColorModel
* @see java.awt.Image
*/
public InternalPngEncoderA(Image image) {
this(image, false, FILTER_NONE, 0);
}
/**
* Class constructor specifying Image to encode, and whether to encode alpha.
*
* @param image A Java Image object which uses the DirectColorModel
* @param encodeAlpha Encode the alpha channel? false=no; true=yes
* @see java.awt.Image
*/
public InternalPngEncoderA(Image image, boolean encodeAlpha) {
this(image, encodeAlpha, FILTER_NONE, 0);
}
/**
* Class constructor specifying Image to encode, whether to encode alpha, and filter to use.
*
* @param image A Java Image object which uses the DirectColorModel
* @param encodeAlpha Encode the alpha channel? false=no; true=yes
* @param whichFilter 0=none, 1=sub, 2=up
* @see java.awt.Image
*/
public InternalPngEncoderA(Image image, boolean encodeAlpha, int whichFilter) {
this(image, encodeAlpha, whichFilter, 0);
}
/**
* Class constructor specifying Image source to encode, whether to encode alpha, filter to use,
* and compression level.
*
* @param image A Java Image object
* @param encodeAlpha Encode the alpha channel? false=no; true=yes
* @param whichFilter 0=none, 1=sub, 2=up
* @param compLevel 0..9
* @see java.awt.Image
*/
public InternalPngEncoderA(Image image, boolean encodeAlpha, int whichFilter, int compLevel) {
this.image = image;
this.encodeAlpha = encodeAlpha;
setFilter(whichFilter);
if (compLevel >= 0 && compLevel <= 9) {
this.compressionLevel = compLevel;
}
}
/**
* Encodes to an outputstream with bytes that are the PNG
* equivalent of the current image.
*
* Alpha encoding is determined by its setting in the constructor.
*
* @param out OutputStream the destination ouotput stream
* @throws IOException
*/
public void encode(OutputStream out) throws IOException {
out.write(pngEncode());
}
/**
* Encodes to an output stream with bytes that are the PNG
* equivalent of the current image, specifying whether to
* encode alpha or not.
*
* @param out OutputStream the destination ouotput stream
* @param encodeAlpha boolean false=no alpha, true=encode alpha
* @throws IOException
*/
public void encode(OutputStream out, boolean encodeAlpha) throws IOException {
out.write(pngEncode(encodeAlpha));
}
/**
* Set the image to be encoded
*
* @param image A Java Image object which uses the DirectColorModel
* @see java.awt.Image
* @see java.awt.image.DirectColorModel
*/
public void setImage(Image image) {
this.image = image;
pngBytes = null;
}
/**
* Creates an array of bytes that is the PNG equivalent of the current image, specifying
* whether to encode alpha or not.
*
* @param encodeAlpha boolean false=no alpha, true=encode alpha
* @return an array of bytes, or null if there was a problem
*/
public byte[] pngEncode(boolean encodeAlpha) {
byte[] pngIdBytes = {-119, 80, 78, 71, 13, 10, 26, 10};
if (image == null) {
return null;
}
width = image.getWidth(null);
height = image.getHeight(null);
/*
* start with an array that is big enough to hold all the pixels
* (plus filter bytes), and an extra 200 bytes for header info
*/
pngBytes = new byte[((width + 1) * height * 3) + 200];
/*
* keep track of largest byte written to the array
*/
maxPos = 0;
bytePos = writeBytes(pngIdBytes, 0);
//hdrPos = bytePos;
writeHeader();
//dataPos = bytePos;
if (writeImageData()) {
writeEnd();
pngBytes = resizeByteArray(pngBytes, maxPos);
}
else {
pngBytes = null;
}
return pngBytes;
}
/**
* Creates an array of bytes that is the PNG equivalent of the current image.
* Alpha encoding is determined by its setting in the constructor.
*
* @return an array of bytes, or null if there was a problem
*/
public byte[] pngEncode() {
return pngEncode(encodeAlpha);
}
/**
* Set the alpha encoding on or off.
*
* @param encodeAlpha false=no, true=yes
*/
public void setEncodeAlpha(boolean encodeAlpha) {
this.encodeAlpha = encodeAlpha;
}
/**
* Retrieve alpha encoding status.
*
* @return boolean false=no, true=yes
*/
public boolean getEncodeAlpha() {
return encodeAlpha;
}
/**
* Set the filter to use
*
* @param whichFilter from constant list
*/
public void setFilter(int whichFilter) {
this.filter = FILTER_NONE;
if (whichFilter <= FILTER_LAST) {
this.filter = whichFilter;
}
}
/**
* Retrieve filtering scheme
*
* @return int (see constant list)
*/
public int getFilter() {
return filter;
}
/**
* Set the compression level to use
*
* @param level 0 through 9
*/
public void setCompressionLevel(int level) {
if (level >= 0 && level <= 9) {
this.compressionLevel = level;
}
}
/**
* Retrieve compression level
*
* @return int in range 0-9
*/
public int getCompressionLevel() {
return compressionLevel;
}
/**
* Increase or decrease the length of a byte array.
*
* @param array The original array.
* @param newLength The length you wish the new array to have.
* @return Array of newly desired length. If shorter than the
* original, the trailing elements are truncated.
*/
protected byte[] resizeByteArray(byte[] array, int newLength) {
byte[] newArray = new byte[newLength];
int oldLength = array.length;
System.arraycopy(array, 0, newArray, 0, Math.min(oldLength, newLength));
return newArray;
}
/**
* 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.
*
* @param data The data to be written into pngBytes.
* @param offset The starting point to write to.
* @return The next place to be written to in the pngBytes array.
*/
protected int writeBytes(byte[] data, int offset) {
maxPos = Math.max(maxPos, offset + data.length);
if (data.length + offset > pngBytes.length) {
pngBytes = resizeByteArray(pngBytes, pngBytes.length + Math.max(1000, data.length));
}
System.arraycopy(data, 0, pngBytes, offset, data.length);
return offset + data.length;
}
/**
* 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.
*
* @param data The data to be written into pngBytes.
* @param nBytes The number of bytes to be written.
* @param offset The starting point to write to.
* @return The next place to be written to in the pngBytes array.
*/
protected int writeBytes(byte[] data, int nBytes, int offset) {
maxPos = Math.max(maxPos, offset + nBytes);
if (nBytes + offset > pngBytes.length) {
pngBytes = resizeByteArray(pngBytes, pngBytes.length + Math.max(1000, nBytes));
}
System.arraycopy(data, 0, pngBytes, offset, nBytes);
return offset + nBytes;
}
/**
* Write a two-byte integer into the pngBytes array at a given position.
*
* @param n The integer to be written into pngBytes.
* @param offset The starting point to write to.
* @return The next place to be written to in the pngBytes array.
*/
protected int writeInt2(int n, int offset) {
byte[] temp = {(byte) ((n >> 8) & 0xff), (byte) (n & 0xff)};
return writeBytes(temp, offset);
}
/**
* Write a four-byte integer into the pngBytes array at a given position.
*
* @param n The integer to be written into pngBytes.
* @param offset The starting point to write to.
* @return The next place to be written to in the pngBytes array.
*/
protected int writeInt4(int n, int offset) {
byte[] temp = {(byte) ((n >> 24) & 0xff),
(byte) ((n >> 16) & 0xff),
(byte) ((n >> 8) & 0xff),
(byte) (n & 0xff)};
return writeBytes(temp, offset);
}
/**
* Write a single byte into the pngBytes array at a given position.
*
* @param b The integer to be written into pngBytes.
* @param offset The starting point to write to.
* @return The next place to be written to in the pngBytes array.
*/
protected int writeByte(int b, int offset) {
byte[] temp = {(byte) b};
return writeBytes(temp, offset);
}
/**
* Write a PNG "IHDR" chunk into the pngBytes array.
*/
protected void writeHeader() {
int startPos;
startPos = bytePos = writeInt4(13, bytePos);
bytePos = writeBytes(IHDR, bytePos);
width = image.getWidth(null);
height = image.getHeight(null);
bytePos = writeInt4(width, bytePos);
bytePos = writeInt4(height, bytePos);
bytePos = writeByte(8, bytePos); // bit depth
bytePos = writeByte((encodeAlpha) ? 6 : 2, bytePos); // direct model
bytePos = writeByte(0, bytePos); // compression method
bytePos = writeByte(0, bytePos); // filter method
bytePos = writeByte(0, bytePos); // no interlace
crc.reset();
crc.update(pngBytes, startPos, bytePos - startPos);
crcValue = crc.getValue();
bytePos = writeInt4((int) crcValue, bytePos);
}
/**
* 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.
*
* @param pixels The array holding the scan lines being built
* @param startPos Starting position within pixels of bytes to be filtered.
* @param width Width of a scanline in pixels.
*/
protected void filterSub(byte[] pixels, int startPos, int width) {
int i;
int offset = bytesPerPixel;
int actualStart = startPos + offset;
int nBytes = width * bytesPerPixel;
int leftInsert = offset;
int leftExtract = 0;
for (i = actualStart; i < startPos + nBytes; i++) {
leftBytes[leftInsert] = pixels[i];
pixels[i] = (byte) ((pixels[i] - leftBytes[leftExtract]) % 256);
leftInsert = (leftInsert + 1) % 0x0f;
leftExtract = (leftExtract + 1) % 0x0f;
}
}
/**
* Perform "up" filtering on the given row.
* Side effect: refills the prior row with current row
*
* @param pixels The array holding the scan lines being built
* @param startPos Starting position within pixels of bytes to be filtered.
* @param width Width of a scanline in pixels.
*/
protected void filterUp(byte[] pixels, int startPos, int width) {
int i, nBytes;
byte currentByte;
nBytes = width * bytesPerPixel;
for (i = 0; i < nBytes; i++) {
currentByte = pixels[startPos + i];
pixels[startPos + i] = (byte) ((pixels[startPos + i] - priorRow[i]) % 256);
priorRow[i] = currentByte;
}
}
/**
* 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.
*
*
* @return true if no errors; false if error grabbing pixels
*/
protected boolean writeImageData() {
int rowsLeft = height; // number of rows remaining to write
int startRow = 0; // starting row to process this time through
int nRows; // how many rows to grab at a time
byte[] scanLines; // the scan lines to be compressed
int scanPos; // where we are in the scan lines
int startPos; // where this line's actual pixels start (used for filtering)
byte[] compressedLines; // the resultant compressed lines
int nCompressed; // how big is the compressed area?
//int depth; // color depth ( handle only 8 or 32 )
PixelGrabber pg;
bytesPerPixel = (encodeAlpha) ? 4 : 3;
Deflater scrunch = new Deflater(compressionLevel);
ByteArrayOutputStream outBytes = new ByteArrayOutputStream(1024);
DeflaterOutputStream compBytes = new DeflaterOutputStream(outBytes, scrunch);
try {
while (rowsLeft > 0) {
nRows = Math.min(32767 / (width * (bytesPerPixel + 1)), rowsLeft);
nRows = Math.max( nRows, 1 );
int[] pixels = new int[width * nRows];
pg = new PixelGrabber(image, 0, startRow,
width, nRows, pixels, 0, width);
try {
pg.grabPixels();
}
catch (Exception e) {
System.err.println("interrupted waiting for pixels!");
return false;
}
if ((pg.getStatus() & ImageObserver.ABORT) != 0) {
System.err.println("image fetch aborted or errored");
return false;
}
/*
* Create a data chunk. scanLines adds "nRows" for
* the filter bytes.
*/
scanLines = new byte[width * nRows * bytesPerPixel + nRows];
if (filter == FILTER_SUB) {
leftBytes = new byte[16];
}
if (filter == FILTER_UP) {
priorRow = new byte[width * bytesPerPixel];
}
scanPos = 0;
startPos = 1;
for (int i = 0; i < width * nRows; i++) {
if (i % width == 0) {
scanLines[scanPos++] = (byte) filter;
startPos = scanPos;
}
scanLines[scanPos++] = (byte) ((pixels[i] >> 16) & 0xff);
scanLines[scanPos++] = (byte) ((pixels[i] >> 8) & 0xff);
scanLines[scanPos++] = (byte) ((pixels[i]) & 0xff);
if (encodeAlpha) {
scanLines[scanPos++] = (byte) ((pixels[i] >> 24) & 0xff);
}
if ((i % width == width - 1) && (filter != FILTER_NONE)) {
if (filter == FILTER_SUB) {
filterSub(scanLines, startPos, width);
}
if (filter == FILTER_UP) {
filterUp(scanLines, startPos, width);
}
}
}
/*
* Write these lines to the output area
*/
compBytes.write(scanLines, 0, scanPos);
startRow += nRows;
rowsLeft -= nRows;
}
compBytes.close();
/*
* Write the compressed bytes
*/
compressedLines = outBytes.toByteArray();
nCompressed = compressedLines.length;
crc.reset();
bytePos = writeInt4(nCompressed, bytePos);
bytePos = writeBytes(IDAT, bytePos);
crc.update(IDAT);
bytePos = writeBytes(compressedLines, nCompressed, bytePos);
crc.update(compressedLines, 0, nCompressed);
crcValue = crc.getValue();
bytePos = writeInt4((int) crcValue, bytePos);
scrunch.finish();
return true;
}
catch (IOException e) {
System.err.println(e.toString());
return false;
}
}
/**
* Write a PNG "IEND" chunk into the pngBytes array.
*/
protected void writeEnd() {
bytePos = writeInt4(0, bytePos);
bytePos = writeBytes(IEND, bytePos);
crc.reset();
crc.update(IEND);
crcValue = crc.getValue();
bytePos = writeInt4((int) crcValue, bytePos);
}
}