/*
Copyright 2000 by J. David Eisenberg
Distributed under the Artistic License.
This license appears at the end of the file.
*/
package sim.util.media;
import java.awt.*;
import java.awt.image.*;
import java.util.zip.*;
import java.io.*;
/** 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.
*
* <p>This code is taken, with permission, from J. David Eisenberg (david@catcode.com), and is
* distributed under the Artistic License.
*/
/*
* 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 distributed under the Artistic License, found at
* the end of this file.
*
* @author J. David Eisenberg
* @version 1.4, 31 March 2000
*/
// NOTE -- change in the package declaration above (per Artistic License) -- Sean
// NOTE -- The original class was called "PngEncoder". It's been renamed to PNGEncoder -- Sean
// NOTE -- various originally protected variables and methods are now private -- Sean
// NOTE -- ENCODE_ALPHA and NO_ALPHA constants deleted -- Sean
// NOTE -- FILTER_LAST deleted -- Sean
// NOTE -- encodeBytes(alpha) deleted -- Sean
public class PNGEncoder extends Object
{
/** Constants for filters */
public static final int FILTER_NONE = 0;
public static final int FILTER_SUB = 1;
public static final int FILTER_UP = 2;
byte[] pngBytes;
byte[] priorRow;
byte[] leftBytes;
Image image;
int width, height;
int bytePos, maxPos;
//int hdrPos, dataPos, endPos;
CRC32 crc = new CRC32();
long crcValue;
boolean encodeAlpha;
int filter;
int bytesPerPixel;
int compressionLevel;
/**
* Class constructor
*
*/
public PNGEncoder()
{
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 PNGEncoder( 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 PNGEncoder( 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 PNGEncoder( 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 PNGEncoder( Image 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 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()
{
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;
}
/**
* 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_UP )
{
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.
*/
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.
*/
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.
*/
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.
*/
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.
*/
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 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.
*/
int writeByte( int b, int offset )
{
byte[] temp = { (byte) b };
return writeBytes( temp, offset );
}
/**
* Write a string into the pngBytes array at a given position.
* This uses the getBytes method, so the encoding used will
* be its default.
*
* @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.
* @see java.lang.String#getBytes()
*/
int writeString( String s, int offset )
{
return writeBytes( s.getBytes(), offset );
}
/**
* Write a PNG "IHDR" chunk into the pngBytes array.
*/
void writeHeader()
{
int startPos;
startPos = bytePos = writeInt4( 13, bytePos );
bytePos = writeString( "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.
*/
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.
*/
void filterUp( byte[] pixels, int startPos, int width )
{
int i, nBytes;
byte current_byte;
nBytes = width * bytesPerPixel;
for (i=0; i < nBytes; i++)
{
current_byte = pixels[startPos + i];
pixels[startPos + i] = (byte) ((pixels[startPos + i] - priorRow[i]) % 256);
priorRow[i] = current_byte;
}
}
/**
* 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
*/
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?
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 );
if (nRows <= 0) nRows = 1; // patch, thanks to David -- Sean
// nRows = rowsLeft;
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("WARNING: PNG image write interrupted waiting for pixels\n\n" + e);
return false;
}
if ((pg.getStatus() & ImageObserver.ABORT) != 0) {
System.err.println("WARNING: PNG 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 = writeString("IDAT", bytePos );
crc.update("IDAT".getBytes());
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("WARNING: IO Error while trying to write PNG image.\n\n" + e.toString());
return false;
}
}
/**
* Write a PNG "IEND" chunk into the pngBytes array.
*/
void writeEnd()
{
bytePos = writeInt4( 0, bytePos );
bytePos = writeString( "IEND", bytePos );
crc.reset();
crc.update("IEND".getBytes());
crcValue = crc.getValue();
bytePos = writeInt4( (int) crcValue, bytePos );
}
}
/*
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may be copied, such that the Copyright Holder maintains some semblance of
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customary fashion, plus the right to make reasonable modifications.
Definitions:
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Holder, and derivatives of that collection of files created through textual
modification.
"Standard Version" refers to such a Package if it has not been modified, or has
been modified in accordance with the wishes of the Copyright Holder.
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package.
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"Reasonable copying fee" is whatever you can justify on the basis of media
cost, duplication charges, time of people involved, and so on. (You will not
be required to justify it to the Copyright Holder, but only to the computing
community at large as a m arket that must bear the fee.)
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there may be fees involved in handling the item. It also means that recipients
of the item may redistribute it under the same conditions they received it.
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*/