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added a 9-year old png encoder from David Eisenberg which I rewrote

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quite a bit to remove all code that handles transparency. With this
highly specialized png writer it is possible to write png images much
faster that with the JRE built-in png writer.
In a second step it can be possible to add concurrency to increase
computation speed further.
pull/1/head
orbiter 12 years ago
parent 276dd6452b
commit c6a1b21399
2 changed files with 189 additions and 2 deletions
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169
source/net/yacy/visualization/PngEncoder.java
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@ -0,0 +1,169 @@
/**
* 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 private fields so that
* PngEncoderB can inherit them (JDE)
* Fixed bug with calculation of nRows
* 23.10.2012
* For the integration into YaCy this class was adopted to YaCy graphics by Michael Christen:
* - removed alpha encoding
* - removed not used code
* - inlined static values
* - inlined all methods that had been called only once
* - moved class objects which appear after all refactoring only within a single method into this method
* - removed a giant number of useless (obvious things) comments and empty lines to increase readability (!)
*/
package net.yacy.visualization;
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;
public class PngEncoder extends Object {
private static final byte IHDR[] = {73, 72, 68, 82};
private static final byte IDAT[] = {73, 68, 65, 84};
private static final byte IEND[] = {73, 69, 78, 68};
private byte[] pngBytes;
private Image image;
private int maxPos;
public PngEncoder(Image image) {
this.image = image;
}
public byte[] pngEncode(int compressionLevel) {
if (image == null) return null;
int width = image.getWidth(null);
int height = image.getHeight(null);
pngBytes = new byte[((width + 1) * height * 3) + 200];
maxPos = 0;
int bytePos = writeBytes(new byte[]{-119, 80, 78, 71, 13, 10, 26, 10}, 0);
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 = writeBytes(new byte[]{8, 2, 0, 0, 0}, bytePos);
CRC32 crc = new CRC32();
crc.reset();
crc.update(pngBytes, startPos, bytePos - startPos);
bytePos = writeInt4((int) crc.getValue(), bytePos);
try {
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
byte[] compressedLines; // the resultant compressed lines
int nCompressed; // how big is the compressed area?
PixelGrabber pg;
Deflater scrunch = new Deflater(compressionLevel);
ByteArrayOutputStream outBytes = new ByteArrayOutputStream(1024);
DeflaterOutputStream compBytes = new DeflaterOutputStream(outBytes, scrunch);
while (rowsLeft > 0) {
nRows = Math.min(32767 / (width * 4), 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 (InterruptedException e) {throw new IOException("interrupted waiting for pixels!");}
if ((pg.getStatus() & ImageObserver.ABORT) != 0) throw new IOException("image fetch aborted or errored");
scanLines = new byte[width * nRows * 3 + nRows];
scanPos = 0;
for (int i = 0; i < width * nRows; i++) {
if (i % width == 0) scanLines[scanPos++] = (byte) 0;
scanLines[scanPos++] = (byte) ((pixels[i] >> 16) & 0xff);
scanLines[scanPos++] = (byte) ((pixels[i] >> 8) & 0xff);
scanLines[scanPos++] = (byte) ((pixels[i]) & 0xff);
}
compBytes.write(scanLines, 0, scanPos);
startRow += nRows;
rowsLeft -= nRows;
}
compBytes.close();
compressedLines = outBytes.toByteArray();
nCompressed = compressedLines.length;
crc.reset();
bytePos = writeInt4(nCompressed, bytePos);
bytePos = writeBytes(IDAT, bytePos);
crc.update(IDAT);
maxPos = Math.max(maxPos, bytePos + nCompressed);
if (nCompressed + bytePos > pngBytes.length) {
pngBytes = resizeByteArray(pngBytes, pngBytes.length + Math.max(1000, nCompressed));
}
System.arraycopy(compressedLines, 0, pngBytes, bytePos, nCompressed);
bytePos += nCompressed;
crc.update(compressedLines, 0, nCompressed);
bytePos = writeInt4((int) crc.getValue(), bytePos);
scrunch.finish();
bytePos = writeInt4(0, bytePos);
bytePos = writeBytes(IEND, bytePos);
crc.reset();
crc.update(IEND);
bytePos = writeInt4((int) crc.getValue(), bytePos);
pngBytes = resizeByteArray(pngBytes, maxPos);
return pngBytes;
} catch (IOException e) {
return null;
}
}
private byte[] resizeByteArray(byte[] array, int newLength) {
byte[] newArray = new byte[newLength];
System.arraycopy(array, 0, newArray, 0, Math.min(array.length, newLength));
return newArray;
}
private 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;
}
private int writeInt4(int n, int offset) {
return writeBytes(new byte[]{(byte) ((n >> 24) & 0xff), (byte) ((n >> 16) & 0xff), (byte) ((n >> 8) & 0xff), (byte) (n & 0xff)}, offset);
}
}

22
source/net/yacy/visualization/RasterPlotter.java
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@ -704,9 +704,9 @@ public class RasterPlotter {
public static ByteBuffer exportImage(final BufferedImage image, final String targetExt) {
// generate an byte array from the given image
//serverByteBuffer baos = new serverByteBuffer();
if ("png".equals(targetExt)) return exportPng(image);
final ByteBuffer baos = new ByteBuffer();
ImageIO.setUseCache(false);
ImageIO.setUseCache(false); // because we write into ram here
try {
ImageIO.write(image, targetExt, baos);
return baos;
@ -716,6 +716,23 @@ public class RasterPlotter {
return null;
}
}
public static ByteBuffer exportPng(final BufferedImage image) {
PngEncoder png = new PngEncoder(image);
try {
final ByteBuffer baos = new ByteBuffer();
byte[] pngbytes = png.pngEncode(1);
if (pngbytes == null) return null;
baos.write(pngbytes);
baos.flush();
baos.close();
return baos;
} catch (IOException e) {
// should not happen
Log.logException(e);
return null;
}
}
public static void main(final String[] args) {
// go into headless awt mode
@ -730,6 +747,7 @@ public class RasterPlotter {
fos.close();
} catch (final IOException e) {}
Log.shutdown();
// open file automatically, works only on Mac OS X
/*
Process p = null;

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