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package com.hammurapi.jcapture;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.lang.ref.Reference;
import java.lang.ref.SoftReference;
import java.nio.ByteBuffer;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.FileChannel.MapMode;
import java.util.zip.Adler32;
import javax.imageio.ImageIO;
/**
* Mapped image is softly kept in memory and also is written to a temporary file.
* If image reference is cleared by the garbage collector, the image is loaded from the file on demand.
* @author Pavel
*
*/
public class MappedImage {
private Reference<BufferedImage> imageRef;
private Reference<byte[]> imageBytesRef;
private MappedByteBuffer buffer;
private int height;
private int width;
private String format;
private long checksum;
private int bytesLength;
public MappedImage(final BufferedImage image, String format, FileChannel channel) throws IOException {
if (format==null) {
throw new NullPointerException("Format is null");
}
class HardReference extends SoftReference<BufferedImage> {
HardReference(BufferedImage referent) {
super(referent);
}
@Override
public BufferedImage get() {
return image;
}
}
imageRef = channel==null ? new HardReference(image) : new SoftReference<BufferedImage>(image);
width = image.getWidth();
height = image.getHeight();
this.format = format;
if (channel!=null) {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
ImageIO.write(imageRef.get(), format, baos);
baos.close();
byte[] imageBytes = baos.toByteArray();
Adler32 adler = new Adler32();
adler.update(imageBytes);
checksum = adler.getValue();
bytesLength = imageBytes.length;
imageBytesRef = new SoftReference<byte[]>(imageBytes);
synchronized (channel) {
long position = channel.position();
channel.write(ByteBuffer.wrap(imageBytes));
buffer = channel.map(MapMode.READ_ONLY, position, imageBytes.length);
}
}
}
public byte[] getImageBytes() throws IOException {
if (imageBytesRef==null) {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
ImageIO.write(imageRef.get(), format, baos);
return baos.toByteArray();
}
byte[] ret = imageBytesRef.get();
if (ret==null) {
buffer.load();
buffer.rewind();
ret = new byte[buffer.remaining()];
buffer.get(ret);
if (bytesLength != ret.length) {
throw new IllegalStateException("Invalid image bytes length, expected "+bytesLength+", got "+ret.length);
}
Adler32 adler = new Adler32();
adler.update(ret);
if (checksum != adler.getValue()) {
throw new IllegalStateException("Invalid image bytes checksum");
}
imageBytesRef = new SoftReference<byte[]>(ret);
}
return ret;
}
/**
* Reads from reference, if reference was cleared, loads from the mapped buffer.
* @return
* @throws IOException
*/
public BufferedImage getImage() throws IOException {
BufferedImage ret = imageRef.get();
if (ret==null) {
ret = ImageIO.read(new ByteArrayInputStream(getImageBytes()));
imageRef = new SoftReference<BufferedImage>(ret);
}
return ret;
}
public int getHeight() {
return height;
}
public int getWidth() {
return width;
}
}
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