import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.Random;

import javax.swing.JPanel;
import javax.swing.Timer;

/**
 * Test Panel
 *
 * Ein Panel mit einigen Bällen, die herumfliegen. Wenn man ins Feld klickt,
 * wechselt die Farbe.
 */
public class PerfDraw extends JPanel {

	private static final long serialVersionUID = 201005061717L;
	private static final int MAX_SPEED = 500;

	private long currTime;
	private long count;
	private double mean; // 9ms

	private long stepdt;

	private int n;
	private Ball[] balls;

	public PerfDraw(int n) {
		this.n = n;
		setLayout(null);
		setBackground(Color.WHITE);
		setPreferredSize(new Dimension(300,100));

		balls = new Ball[n];
		Random rand = new Random();
		for (int i=0;i<n;i++) {
			balls[i] = new Ball(rand.nextInt(600),
					rand.nextInt(400),
					rand.nextInt(MAX_SPEED)-MAX_SPEED/2,
					rand.nextInt(MAX_SPEED)-MAX_SPEED/2,
					rand.nextInt(20)+4,
					new Color(rand.nextInt(256*256*256)));
		}
		addMouseListener(new MouseAdapter() {
			public void mouseReleased(MouseEvent e) {
				setBackground(new Color(new Random().nextInt(256*256*256)));
			}
		});

		final int delay = 30;
		new Timer(delay,new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				long dt = (System.nanoTime()-currTime)/1000000;
				currTime = System.nanoTime();
				step(dt<=delay*2 ?dt :delay*2);
			}
		}) {
			private static final long serialVersionUID = 1L;
			public void start() {
				currTime = System.nanoTime();
				super.start();
			}
		}.start();
	}

	public void paint(Graphics g) {
		long t0 = System.nanoTime();
		super.paint(g);
		long dt = (System.nanoTime()-t0)/1000000;
		mean = (mean*(count++)+dt)/count;
		g.setColor(Color.RED);
		g.drawString("Bälle: "+n+" ms",0,12);
		g.drawString("Bälle: "+n+" ms",1,12);
		g.drawString("paint: "+dt+" ms",0,24);
		g.drawString("paint: "+dt+" ms",1,24);
		g.drawString("step: "+stepdt+" ms",0,36);
		g.drawString("step: "+stepdt+" ms",1,36);
	}

	public void paintComponent(Graphics g) {
		// gekürzte Version
		super.paintComponent(g);
		for (Ball ball:balls) {
			ball.paint(g);
		}
	}

	private void step(long dt) {
		long t0 = System.nanoTime();
		for (Ball ball:balls) {
			ball.step(dt);
			if (ball.vx<0 && ball.x<0) ball.vx = -ball.vx;
			if (ball.vy<0 && ball.y<0) ball.vy = -ball.vy;
			if (ball.vx>0 && ball.x+ball.size>=getWidth()) ball.vx = -ball.vx;
			if (ball.vy>0 && ball.y+ball.size>=getHeight()) ball.vy = -ball.vy;
		}
		getParent().repaint(); // Hack für diese Version
		stepdt = (System.nanoTime()-t0)/1000000;
	}

	private class Ball {
		private float x, y;
		private float vx, vy;
		private int size;
		private Color col;

		public Ball(int x, int y, float vx, float vy, int size, Color col) {
			this.x = x;
			this.y = y;
			this.vx = vx;
			this.vy = vy;
			this.size = size;
			this.col = col;
		}

		private void step(long dt) {
			x = x+vx*dt/1000;
			y = y+vy*dt/1000;
		}

		public void paint(Graphics g) {
			g.setColor(col);
			g.fillOval((int)Math.round(x),
					(int)Math.round(y),
					size,size);
		}
	}

}