--- /dev/null
+package org.ibex.xt;
+
+import java.awt.Image;
+import java.awt.image.ImageObserver;
+import java.awt.image.PixelGrabber;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.util.zip.CRC32;
+import java.util.zip.Deflater;
+import java.util.zip.DeflaterOutputStream;
+
+/**
+ * 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>Thanks to Jay Denny at KeyPoint Software
+ * http://www.keypoint.com/
+ * 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-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
+ */
+
+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 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 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(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);
+ }
+
+}
projects / org.ibex.xt.git / blobdiff