Simple LWJGL Screenshot example

package main;

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.nio.FloatBuffer;
import javax.imageio.ImageIO;

import org.lwjgl.BufferUtils;
import org.lwjgl.LWJGLException;
import org.lwjgl.input.Keyboard;
import org.lwjgl.opengl.Display;
import org.lwjgl.opengl.DisplayMode;
import org.lwjgl.opengl.GL11;

public class MainWindow {
    /**
     * Display width
     */
    private static final int WIDTH = 400;

    /**
     * Display height
     */
    private static final int HEIGHT = 300;

    /**
     * Entry point
     * @param args
     */
    public static void main(String[] args) {
        MainWindow mw = new MainWindow();
        if(mw.init()) {
            mw.mainLoop();
        }
    }

    /**
     * Empty constructor.
     */
    public MainWindow() {

    }

    /**
     * Initializes the OpenGL Context (Display) and the Keyboard.
     * @return true if successful
     */
    public boolean init() {
        try {
            Display.setDisplayMode(new DisplayMode(WIDTH, HEIGHT));
            Display.setTitle("Screenshots");
            Display.create();
            Keyboard.create();
            return true;
        } catch (LWJGLException e) {
            e.printStackTrace();
        }
        return false;
    }

    /**
     * Handles the mainLoop.
     */
    public void mainLoop() {
        GL11.glClearColor(0, 0, 0, 0);

        while(!Display.isCloseRequested()) {

            // handle input
            while(Keyboard.next()) {
                if(Keyboard.getEventKeyState()) {
                    switch(Keyboard.getEventKey()) {
                        case Keyboard.KEY_F2: saveScreenshot(); break;
                    }
                }
            }

            GL11.glClear(GL11.GL_COLOR_BUFFER_BIT);

            // draw a red triangle
            GL11.glColor3f(1, 0, 0);
            GL11.glBegin(GL11.GL_LINE_LOOP);
            GL11.glVertex2f(0, 0);
            GL11.glVertex2f(0, 1);
            GL11.glVertex2f(1, 0);
            GL11.glEnd();

            Display.update();
        }
    }

    /**
     * Reads the current front buffer and stores it into a file.
     */
    private void saveScreenshot() {
        // read current buffer
        FloatBuffer imageData = BufferUtils.createFloatBuffer(WIDTH * HEIGHT * 3);
        GL11.glReadPixels(0, 0, WIDTH, HEIGHT, GL11.GL_RGB, GL11.GL_FLOAT, imageData);
        imageData.rewind();

        // fill rgbArray for BufferedImage
        int[] rgbArray = new int[WIDTH * HEIGHT];
        for(int y = 0; y < HEIGHT; ++y) {
            for(int x = 0; x < WIDTH; ++x) {
                int r = (int)(imageData.get() * 255) << 16;
                int g = (int)(imageData.get() * 255) << 8;
                int b = (int)(imageData.get() * 255);
                int i = ((HEIGHT - 1) - y) * WIDTH + x;
                rgbArray[i] = r + g + b;
            }
        }

        // create and save image
        BufferedImage image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
        image.setRGB(0, 0, WIDTH, HEIGHT, rgbArray, 0, WIDTH);
        File outputfile = getNextScreenFile();
        try {
            ImageIO.write(image, "png", outputfile);
        } catch (IOException e) {
            e.printStackTrace();
            System.err.println("Can not save screenshot!");
        }
    }

    /**
     * Generates a screenshot file.
     * @return generated File
     */
    private File getNextScreenFile() {
        // create image name
        String fileName = "screenshot_" + System.currentTimeMillis();
        File imageToSave = new File(fileName + ".png");

        // check for duplicates
        int duplicate = 0;
        while(imageToSave.exists()) {
            imageToSave = new File(fileName + "_" + ++duplicate + ".png");
        }

        return imageToSave;
    }
}