Kryonet，无法发送BufferedImage

Question

I'm still learning Java and I have searched into the Javadoc of Kryonet and didn't find any answers to my problem.

I am adding a webcam function to a simple chat program.

I am currently trying to transfer a single frame taken by my webcam to another computer.

Kryonet allows me to send "homemade" packets, so made this packet :

Packet9WebcamFrame.java

import java.awt.image.BufferedImage;

public class Packet9WebcamFrame{
    public BufferedImage frame;
}

In my client I then had to register this packet :

client.getKryo().register(Packet9WebcamFrame.class);

But then i had errors that made me register other classes :

client.getKryo().register(java.awt.image.BufferedImage.class);
client.getKryo().register(java.awt.image.ComponentColorModel.class);
client.getKryo().register(java.awt.color.ICC_ColorSpace.class);
client.getKryo().register(float[].class);
client.getKryo().register(java.awt.color.ICC_ProfileRGB.class);
client.getKryo().register(short[].class);
client.getKryo().register(byte[].class);
client.getKryo().register(int[].class);
client.getKryo().register(sun.awt.image.SunWritableRaster.class);
client.getKryo().register(java.awt.image.DataBufferByte.class);
client.getKryo().register(byte[][].class);

So, now, when my client receive the packet saying "Hello I need you to send me a webcam frame please", it does that :

webcam.open();

    if (webcam.isOpen())
    {

        Packet9WebcamFrame wFrame = new Packet9WebcamFrame();

        wFrame.frame = webcam.getImage();

        //We send the frame via the packet
        try
        {
            Main.client.sendTCP(wFrame);
        }

        catch (Exception e)
        {
            e.printStackTrace();
        }
        System.out.println("I have sent a webcam frame");

        webcam.close();

    }       

After that i hoped it would work, but still an error :

com.esotericsoftware.kryo.KryoException: java.nio.BufferOverflowException Serialization trace: bankdata (java.awt.image.DataBufferByte) dataBuffer (sun.awt.image.SunWritableRaster) raster (java.awt.image.BufferedImage)

frame (com.jmr.monitor.packets.Packet9WebcamFrame)

at com.esotericsoftware.kryo.serializers.FieldSerializer$ObjectField.write(FieldSerializer.java:585) at com.esotericsoftware.kryo.serializers.FieldSerializer.write(FieldSerializer.java:213) at com.esotericsoftware.kryo.Kryo.writeObject(Kryo.java:504) at com.esotericsoftware.kryo.serializers.FieldSerializer$ObjectField.write(FieldSerializer.java:564) at com.esotericsoftware.kryo.serializers.FieldSerializer.write(FieldSerializer.java:213) at com.esotericsoftware.kryo.Kryo.writeObject(Kryo.java:504) at com.esotericsoftware.kryo.serializers.FieldSerializer$ObjectField.write(FieldSerializer.java:564) at com.esotericsoftware.kryo.serializers.FieldSerializer.write(FieldSerializer.java:213) at com.esotericsoftware.kryo.Kryo.writeObject(Kryo.java:504) at com.esotericsoftware.kryo.serializers.FieldSerializer$ObjectField.write(FieldSerializer.java:564) at com.esotericsoftware.kryo.serializers.FieldSerializer.write(FieldSerializer.java:213) at com.esotericsoftware.kryo.Kryo.writeClassAndObject(Kry o.java:571) at com.esotericsoftware.kryonet.KryoSerialization.write(KryoSerialization.java:50) at com.esotericsoftware.kryonet.TcpConnection.send(TcpConnection.java:192) at com.esotericsoftware.kryonet.Connection.sendTCP(Connection.java:59) at com.jmr.monitor.PacketHandler.handlePacket4(PacketHandler.java:131) at com.jmr.monitor.Main$1.received(Main.java:93)

So, it's a bufferOverflow issue, i've tried a few things in my client's constructor such as increasing the buffer size but no luck so far.

Any idea on how to fix this annoying issue ?

Thank you in advance.

Regards,

Azsde.

Answer 1

A package has a fixed size (I guess). I stuck with a similar problem. It boils down that BufferedImage does not have a non-argument constructor and if one uses different methods to get around this problem like using no constructor at all when deserializing, it goes south.

So basically what you want is serialize a buffered image. One thing you can do is provide your own serializer (it can be read on their github page) or extract an RGB version or store the byte / int content of the image or even write a PNG to memory and send the PNG/JPG instead (gives you compression).