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- prepared PngEncoder for concurrency: PixelGrabber.grabPixels is the

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main time-consuming process. This shall be done in concurrency.
- added concurrent processes to call the PixelGrabber and framework to
do that (queues)

It is now possible to create 4k-Images (3840x2160) i.e. with the Network
Graphics servlet
pull/1/head
Michael Peter Christen 12 years ago
parent e9c6f4ce2e
commit b3ffcde0c7
1 changed files with 73 additions and 22 deletions
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95
source/net/yacy/visualization/PngEncoder.java
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@ -49,6 +49,8 @@
* then assign an exact-sized byte[] which makes resizing afterwards superfluous
* - after all enhancements all class objects were removed; result is just one short static method
* - made objects final where possible
* - prepared process for concurrency: PixelGrabber.grabPixels is the main time-consuming process. This shall be done in concurrency.
* - added concurrent processes to call the PixelGrabber and framework to do that (queues)
*/
package net.yacy.visualization;
@ -58,12 +60,18 @@ 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.Map;
import java.util.TreeMap;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.zip.CRC32;
import java.util.zip.Deflater;
import java.util.zip.DeflaterOutputStream;
public class PngEncoder extends Object {
private static final int[] POISON_IN = new int[0];
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};
@ -72,35 +80,53 @@ public class PngEncoder extends Object {
if (image == null) throw new IOException("image == null");
final int width = image.getWidth(null);
final int height = image.getHeight(null);
int rowsLeft = height; // number of rows remaining to write
// prepare an input list for concurrent PixelGrabber computation
final BlockingQueue<int[]> grabberInput = new LinkedBlockingQueue<int[]>();
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
final Deflater scrunch = new Deflater(compressionLevel);
final ByteArrayOutputStream outBytes = new ByteArrayOutputStream(1024);
final DeflaterOutputStream compBytes = new DeflaterOutputStream(outBytes, scrunch);
int rowsLeft = height; // number of rows remaining to write
while (rowsLeft > 0) {
nRows = Math.min(32767 / (width * 4), rowsLeft);
nRows = Math.max(nRows, 1);
int[] pixels = new int[width * nRows];
PixelGrabber 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);
int nRows = Math.max(Math.min(32767 / (width * 4), rowsLeft), 1); // how many rows to grab at a time
grabberInput.add(new int[]{startRow, nRows});
startRow += nRows;
rowsLeft -= nRows;
}
// do the PixelGrabber computation and allocate the result in the right order
final TreeMap<Integer, ScanLines> scan = new TreeMap<Integer, ScanLines>();
if (grabberInput.size() > 80) {
ArrayList<Thread> ts = new ArrayList<Thread>();
int tc = Math.min(grabberInput.size() / 40, Runtime.getRuntime().availableProcessors());
for (int i = 0; i < tc; i++) {
grabberInput.add(POISON_IN);
Thread t = new Thread() {
public void run() {
int[] gi;
try {
while ((gi = grabberInput.take()) != POISON_IN) pixelGrabber(image, width, gi[0], gi[1], scan);
} catch (InterruptedException e) {} catch (IOException e) {}
}
};
t.start();
ts.add(t);
if (grabberInput.size() == 0) break;
}
for (Thread t: ts) try {t.join();} catch (InterruptedException e) {}
} else {
for (int[] gi: grabberInput) pixelGrabber(image, width, gi[0], gi[1], scan);
}
// finally write the result of the concurrent calculation into an DeflaterOutputStream to compress the png
final Deflater scrunch = new Deflater(compressionLevel);
ByteArrayOutputStream outBytes = new ByteArrayOutputStream(1024);
final DeflaterOutputStream compBytes = new DeflaterOutputStream(outBytes, scrunch);
for (Map.Entry<Integer, ScanLines> entry: scan.entrySet()) {
compBytes.write(entry.getValue().scan, 0, entry.getValue().count);
}
compBytes.close();
final byte[] compressedLines = outBytes.toByteArray();
outBytes.close();
outBytes = null;
final int nCompressed = compressedLines.length;
final byte[] pngBytes = new byte[nCompressed + 57]; // yes thats the exact size, not too less, not too much. No resizing needed.
int bytePos = writeBytes(pngBytes, new byte[]{-119, 80, 78, 71, 13, 10, 26, 10}, 0);
@ -138,5 +164,30 @@ public class PngEncoder extends Object {
System.arraycopy(data, 0, target, offset, data.length);
return offset + data.length;
}
private final static void pixelGrabber(final Image image, final int width, int y, int nRows, TreeMap<Integer, ScanLines> scan) throws IOException {
int[] pixels = new int[width * nRows];
PixelGrabber pg = new PixelGrabber(image, 0, y, 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");
byte[] scanLines = new byte[width * nRows * 4]; // the scan lines to be compressed
int scanPos = 0; // where we are in the scan lines
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);
}
synchronized (scan) {scan.put(y, new ScanLines(scanLines, scanPos));}
}
private static class ScanLines {
protected byte[] scan;
protected int count;
public ScanLines(final byte[] scan, final int count) {
this.scan = scan;
this.count = count;
}
}
}

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