package org.freehep.graphicsio.png; //package com.keypoint; /** * 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 */ /** * Added ImageObserver so that getHeight, getWidth calls work properly. * * @author M.Donszelmann */ import java.awt.Image; import java.awt.Toolkit; import java.awt.image.ImageObserver; import java.awt.image.PixelGrabber; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.util.ArrayList; import java.util.Iterator; import java.util.List; import java.util.zip.CRC32; import java.util.zip.Deflater; import java.util.zip.DeflaterOutputStream; public class PNGEncoder extends Object implements ImageObserver { /** 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; protected List keys = new ArrayList(); protected List text = new ArrayList(); 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; } } public void addText(String key, String value) { if ((key == null) || (key.length() == 0)) key = "Comment"; keys.add(key.substring(0, Math.min(79, key.length()))); text.add(value); } /** * Set the image to be encoded * * @param image A Java Image object which uses the DirectColorModel * @see java.awt.Image */ public void setImage(Image image) { this.image = image; pngBytes = null; } /** method to wait for image */ private int imageStatus; public boolean imageUpdate(Image image, int flags, int x, int y, int width, int height) { imageStatus = flags; if (((flags & ALLBITS) == ALLBITS) || ((flags & (ABORT | ERROR)) != 0)) { return false; } return true; } /** * 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; } imageStatus = 0; boolean status = Toolkit.getDefaultToolkit().prepareImage(image, -1, -1, this); if (!status) { while (((imageStatus & (ALLBITS)) == 0) && ((imageStatus & (ABORT | ERROR)) == 0)) { try { Thread.sleep(100); } catch (Exception e) { } } // FIXED: moved this inside the "if (!status)" area if ((imageStatus & (ALLBITS)) == 0) { 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(); for (Iterator ik = keys.iterator(), iv = text.iterator(); ik.hasNext() && iv.hasNext();) { writeText((String) ik.next(), (String) iv.next()); } 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 string into the pngBytes array at a given position. This uses the * getBytes method, so the encoding used will be its default. * * @param s The String 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); } protected void writeText(String key, String value) { int startPos; int len = key.length() + 1 + value.length(); startPos = bytePos = writeInt4(len, bytePos); bytePos = writeString("tEXt", bytePos); bytePos = writeString(key, bytePos); bytePos = writeByte(0, bytePos); bytePos = writeString(value, bytePos); 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 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() { 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); // 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 < 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(e.toString()); return false; } } /** * 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); } }