Zadanie z animacji – odbicia. Rozwiązanie

Kody źródłowe z odcinka

package pl.am.swing.animtions3;

import javax.swing.*;
import java.awt.*;

public class MyFrame extends JFrame {

    public MyFrame() {
        setTitle("Zdarzenia myszy");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(1000, 800);

        add(new MyComponent());
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(() -> {
            MyFrame myFrame = new MyFrame();
            myFrame.setVisible(true);
        });

    }
}

package pl.am.swing.animtions3;

import javax.swing.*;
import java.awt.*;

public class MyComponent extends JComponent {

    private int rectangleX = 500;
    private int rectangleY = 0;
    private int rectangleWidth = 50;
    private int rectangleHeight = 50;
    private int speedX = 5;
    private int speedY = 10;

    private int maxWidth = 800;
    private int maxHeight = 600;

    public MyComponent() {
        Timer timer = new Timer(40, e -> {
            rectangleX += speedX;
            rectangleY += speedY;

            if (rectangleX + rectangleWidth > maxWidth) {
                rectangleX = maxWidth - rectangleWidth;
                speedX = -speedX;
            }

            if (rectangleY + rectangleHeight > maxHeight) {
                rectangleY = maxHeight - rectangleHeight;
                speedY = -speedY;
            }

            if (rectangleX < 0) {
                rectangleX = 0;
                speedX = -speedX;
            }

            if (rectangleY < 0) {
                rectangleY = 0;
                speedY = -speedY;
            }

            repaint();
        });

        timer.start();
    }

    @Override
    protected void paintComponent(Graphics g) {
        Toolkit.getDefaultToolkit().sync();
        Graphics2D graphics2D = (Graphics2D) g;

        Point point = new Point(rectangleX, rectangleY);
        Dimension dimension = new Dimension(rectangleWidth, rectangleHeight);

        Rectangle limit = new Rectangle(0, 0, maxWidth, maxHeight);
        graphics2D.setPaint(Color.LIGHT_GRAY);
        graphics2D.fill(limit);

        Rectangle rectangle = new Rectangle(point, dimension);
        graphics2D.setPaint(Color.BLUE);
        graphics2D.fill(rectangle);


    }
}