package aurelienribon.utils.swing;

import java.lang.reflect.InvocationTargetException;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public abstract class DrawingCanvas extends JPanel {
        private Thread thread = null;
        private boolean isRunning = false;

        public DrawingCanvas start() {
                thread = new Thread(loop);
                thread.start();
                isRunning = true;
                return this;
        }

        public void stop() {
                isRunning = false;
                try {
                        thread.join();
                } catch (InterruptedException ex) {
                }
        }

        protected abstract void update(int elapsedMillis);

        private Runnable loop = new Runnable() {
                private long lastMillis;

                @Override public void run() {
                        lastMillis = System.currentTimeMillis();

                        while (isRunning) {
                                try {
                                        final long millis = System.currentTimeMillis();
                                        final long delta = millis - lastMillis;
                                        lastMillis = millis;

                                        SwingUtilities.invokeAndWait(new Runnable() {@Override public void run() {update((int) delta);}});
                                        Thread.sleep(16);

                                } catch (InterruptedException ex) {
                                } catch (InvocationTargetException ex) {
                                }
                        }
                }
        };
}