/** * 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, * * @author J. David Eisenberg * @version 1.4, 31 March 2000 */ // Slightly modified by Peter Csizmadia (cspeter) to work with Chemaxon Marvin package chemaxon.marvin.modules; import chemaxon.marvin.util.ProgressObserver; // since 2001.04.26/Marvin 2.7.9 import java.awt.*; import java.awt.image.*; import java.util.*; import java.util.zip.*; import java.io.*; public class PngEncoder 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 filters */ public static final int FILTER_NONE = 0; public static final int FILTER_SUB = 1; public static final int FILTER_UP = 2; public static final int FILTER_LAST = 2; protected byte[] pngBytes; protected byte[] priorRow; protected byte[] leftBytes; protected Image image; protected int width, height; protected int bytePos, maxPos; protected int hdrPos, dataPos, endPos; protected CRC32 crc = new CRC32(); protected long crcValue; protected boolean encodeAlpha; protected int filter; protected int bytesPerPixel; protected int compressionLevel; private ProgressObserver progressObserver; // cspeter 2001.04.26 /** * 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, ProgressObserver obs ) // cspeter 2001.04.26 { this(image, false, FILTER_NONE, 0); progressObserver = obs; } /** * 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( boolean encodeAlpha ) { byte[] pngIdBytes = { -119, 80, 78, 71, 13, 10, 26, 10 }; int i; if (image == null) { return null; } width = image.getWidth( null ); height = image.getHeight( null ); this.image = image; /* * 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 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 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() */ protected int writeString( String s, int offset ) { return writeBytes( s.getBytes(), offset ); } /** * Write a PNG "IHDR" chunk into the pngBytes array. */ protected 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. */ 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; byte current_byte; 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 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 */ protected boolean writeImageData() { if(progressObserver != null) { // cspeter 2001.04.26 progressObserver.initProgressMonitor( "Writing "+height+" scanlines", 0, height); } 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) { if(progressObserver != null) { // cspeter 2001.04.26 if(!progressObserver.setProgressValue(height - rowsLeft)) return false; } nRows = Math.min( 32767 / (width*(bytesPerPixel+1)), rowsLeft ); // 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("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> 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( e.toString()); return false; } finally { if(progressObserver != null) { // cspeter 2001.04.26 progressObserver.setProgressValue(height); } } } /** * Write a PNG "IEND" chunk into the pngBytes array. */ protected void writeEnd() { bytePos = writeInt4( 0, bytePos ); bytePos = writeString( "IEND", bytePos ); crc.reset(); crc.update("IEND".getBytes()); crcValue = crc.getValue(); bytePos = writeInt4( (int) crcValue, bytePos ); } }