java timer change delay with button

Question

I have an animation that i would like to speed up and slow down with a button click. I've looked around quite a bit and cant find a solution. Currently I have an actionlistener for the button that changes the value of the delay variable and restarts the timer.

Can anyone please advise. Thanks

Answer 1

Rather then changing the timer, which other parts of your animation might rely on, I would change the speed of the object.

This is little subjective. My example has an object capable of changing speeds over the same period of time. You may actually be required to alter how long the animation plays for instead, which will require a change in the time. This brings up other issues.

One way to achieve this is, is to actually have a timer that ticks at a regular interval and a model that reacts to those ticks. This means that if you adjust the duration, the heart beat won't be effected, you'd just need to adjust the distance through the animation. This is how the Timing Framework works and I believe Trident follows a similar design

public class TestAnimationSpeed {

    public static void main(String[] args) {
        new TestAnimationSpeed();
    }

    public TestAnimationSpeed() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }

                JFrame frame = new JFrame();
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(new AnimationPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class AnimationPane extends JPanel {

        private JSlider slider;
        private BouncyPane bouncyPane;

        public AnimationPane() {
            setLayout(new BorderLayout());
            bouncyPane = new BouncyPane();
            add(bouncyPane, BorderLayout.CENTER);
            slider = new JSlider(1, 11);
            slider.setMajorTickSpacing(2);
            slider.setPaintTicks(true);
            add(slider, BorderLayout.SOUTH);
            slider.addChangeListener(new ChangeListener() {
                @Override
                public void stateChanged(ChangeEvent e) {
                    bouncyPane.setVerticalSpeed(slider.getValue());
                }
            });
            slider.setValue(4);
        }

    }

    public class BouncyPane extends JPanel {

        private int dy = 4;
        private Ellipse2D ball;

        public BouncyPane() {
            ball = new Ellipse2D.Float(100, 0, 10, 10);
            Timer timer = new Timer(1000/60, new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    double y = ball.getY();
                    y += dy;
                    if (y + ball.getHeight() > getHeight()) {
                        y = getHeight() - ball.getHeight();
                        dy *= -1;
                    } else if (y < 0) {
                        y = 0;
                        dy *= -1;
                    }
                    ball.setFrame(ball.getX(), y, ball.getWidth(), ball.getHeight());
                    repaint();
                }
            });
            timer.setRepeats(true);
            timer.setCoalesce(true);
            timer.start();
        }

        public void setVerticalSpeed(int speed) {
            if (dy < 0 && speed > 0) {
                dy = -speed;
            } else {
                dy = speed;
            }
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g.create();
            g2d.setColor(Color.RED);
            g2d.fill(ball);
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(200, 200);
        }

    }

}