package com.keypoint;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.awt.image.DataBuffer;
import java.awt.image.IndexColorModel;
import java.awt.image.ImageObserver;
import java.awt.image.PixelGrabber;
import java.awt.image.WritableRaster;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.zip.CRC32;
import java.util.zip.Deflater;
import java.util.zip.DeflaterOutputStream;
/**
* PngEncoderB takes a Java BufferedImage object and creates a byte string which can be saved as a PNG file.
* The encoder will accept BufferedImages with eight-bit samples
* or 4-byte ARGB samples.
*
* <p>There is also code to handle 4-byte samples returned as
* one int per pixel, but that has not been tested.</p>
*
* <p>Thanks to Jay Denny at KeyPoint Software
* <code>http://www.keypoint.com/</code>
* who let me develop this code on company time.</p>
*
* <p>You may contact me with (probably very-much-needed) improvements,
* comments, and bug fixes at:</p>
*
* <p><code>david@catcode.com</code></p>
*
* <p>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.<p>
*
* <p>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.</p>
*
* <p>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
* <code>http://www.gnu.org/copyleft/lesser.html</code></p>
*
* @author J. David Eisenberg
* @version 1.5, 19 Oct 2003
*
* CHANGES:
* --------
* 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)
*/
public class PngEncoderB extends PngEncoder
{
/** PLTE tag. */
private static final byte PLTE[] = { 80, 76, 84, 69 };
protected BufferedImage image;
protected WritableRaster wRaster;
protected int tType;
/**
* Class constructor
*
*/
public PngEncoderB()
{
this( null, false, FILTER_NONE, 0 );
}
/**
* Class constructor specifying BufferedImage to encode, with no alpha channel encoding.
*
* @param image A Java BufferedImage object
*/
public PngEncoderB( 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 PngEncoderB( 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 PngEncoderB( 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 PngEncoderB( 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 };
int i;
if (image == null)
{
System.err.println("pngEncode: image is null; returning null");
return null;
}
width = image.getWidth( null );
height = image.getHeight( null );
this.image = image;
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<width*nRows; i++)
{
if (i % width == 0)
{
scanLines[scanPos++] = (byte) filter;
startPos = scanPos;
}
if (bytesPerPixel == 1) // assume TYPE_BYTE, indexed
{
scanLines[scanPos++] = pixels[readPos++];
}
else if (tType == DataBuffer.TYPE_BYTE)
{
scanLines[scanPos++] = pixels[readPos++];
scanLines[scanPos++] = pixels[readPos++];
scanLines[scanPos++] = pixels[readPos++];
if (encodeAlpha)
{
scanLines[scanPos++] = pixels[readPos++];
}
else
{
readPos++;
}
}
else if (tType == DataBuffer.TYPE_USHORT)
{
short pxl = sPixels[readPos++];
if (type == BufferedImage.TYPE_USHORT_565_RGB) {
scanLines[scanPos++] = (byte) ((pxl >> 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;
}
}
}