linux, framebuffer, no X, swing
When running a Java/Swing application on Linux, using X, I'm experiencing poor performance. This is partly caused by X. I'm therefore wondering if there is a possibility to directly use the video memory.
With java NIO you can map a file into a buffer and write directly to this buffer. You can force Swing to paint in this buffer.
Mapping to a normal file works, but mapping to /dev/fb0 fails. The size of this device file is 0.
Is there anybody who has tried the same thing? Or is there someone who runs a Java/Swing appication on Linux without X in some other way ?
Test program:
import java.nio.*;
import java.nio.channels.*;
import java.io.*;
publicclass MemoryMapTest{
static String filename;
public MemoryMapTest(){
RandomAccessFile memFile;
try{
memFile =new RandomAccessFile(filename,"rw");
FileChannel fileChannel = memFile.getChannel();
try{
MappedByteBuffer buffer = fileChannel.map(FileChannel.MapMode.READ_WRITE, 0, 800);
for (int i = 0; i < 800; i++){
byte val = (byte)(255 - i);
buffer.put(i, val);
}
}catch (IOException ex){
ex.printStackTrace();
}
try{
fileChannel.close();
memFile.close();
}catch (IOException ex){
ex.printStackTrace();
}
}catch (FileNotFoundException ex){
ex.printStackTrace();
}
}
publicstaticvoid main(String argv[]){
if (argv.length > 0){
filename = argv[0];
}else{
filename ="memfile";
}
new MemoryMapTest();
}
}
