import java.lang.reflect.InvocationTargetException;

 * BezierAnimationPanel

 *

 * @author Jim Graham

 * @author Jeff Dinkins (removed dynamic setting changes, made swing friendly)

 * @version 1.16 11/17/05

 */

    public static enum BezierColor {

        BACKGROUND, OUTER, GRADIENT_A, GRADIENT_B

    }

    private final Map<BezierColor, Color> colors = new Hashtable<BezierColor, Color>();

    private GradientPaint gradient = null;

    private static final int NUMPTS = 6;

    private final float[] animpts = new float[NUMPTS * 2];

    private final float[] deltas = new float[NUMPTS * 2];

    private BufferedImage img;

    private Thread anim;

    private final Object lock = new Object();

    /**

     * BezierAnimationPanel Constructor

     */

    public BezierAnimationPanel() {

        setOpaque(true);

        colors.put(BACKGROUND, new Color(0, 0, 153));

        colors.put(OUTER, new Color(255, 255, 255));

        colors.put(GRADIENT_A, new Color(255, 0, 101));

        colors.put(GRADIENT_B, new Color(255, 255, 0));

        addHierarchyListener(new HierarchyListener() {

            public void hierarchyChanged(HierarchyEvent e) {

                if (isShowing()) {

                    start();

                } else {

                    stop();

                }

            }

        });

    }

    public Color getBezierColor(BezierColor bezierColor) {

        return colors.get(bezierColor);

    }

    public void setBezierColor(BezierColor bezierColor, Color value) {

        if (value != null) {

            colors.put(bezierColor, value);

        }

    }

    public void start() {

        Dimension size = getSize();

        for (int i = 0; i < animpts.length; i += 2) {

            animpts[i] = (float) (Math.random() * size.width);

            animpts[i + 1] = (float) (Math.random() * size.height);

            deltas[i] = (float) (Math.random() * 4.0 + 2.0);

            deltas[i + 1] = (float) (Math.random() * 4.0 + 2.0);

            if (animpts[i] > size.width / 6.0f) {

                deltas[i] = -deltas[i];

            }

            if (animpts[i + 1] > size.height / 6.0f) {

                deltas[i + 1] = -deltas[i + 1];

            }

        }

        anim = new Thread(this);

        anim.setPriority(Thread.MIN_PRIORITY);

        anim.start();

    }

    public synchronized void stop() {

        anim = null;

        notify();

    }

    private static void animate(float[] pts, float[] deltas, int index, int limit) {

        float newpt = pts[index] + deltas[index];

        if (newpt <= 0) {

            newpt = -newpt;

            deltas[index] = (float) (Math.random() * 3.0 + 2.0);

        } else if (newpt >= (float) limit) {

            newpt = 2.0f * limit - newpt;

            deltas[index] = -(float) (Math.random() * 3.0 + 2.0);

        }

        pts[index] = newpt;

    }

    public void run() {

        Thread me = Thread.currentThread();

        while (getSize().width <= 0) {

            try {

                Thread.sleep(500);

            } catch (InterruptedException e) {

                return;

            }

        }

        Graphics2D g2d = null;

        Graphics2D bufferG2D = null;

        BasicStroke solid = new BasicStroke(9.0f, BasicStroke.CAP_BUTT, BasicStroke.JOIN_ROUND, 9.0f);

        GeneralPath gp = new GeneralPath(GeneralPath.WIND_NON_ZERO);

        int rule = AlphaComposite.SRC_OVER;

        AlphaComposite opaque = AlphaComposite.SrcOver;

        AlphaComposite blend = AlphaComposite.getInstance(rule, 0.9f);

        AlphaComposite set = AlphaComposite.Src;

        Dimension oldSize = getSize();

        Shape clippath = null;

        while (anim == me) {

            Dimension size = getSize();

            if (size.width != oldSize.width || size.height != oldSize.height) {

                img = null;

                clippath = null;

                if (bufferG2D != null) {

                    bufferG2D.dispose();

                    bufferG2D = null;

                }

            }

            oldSize = size;

            if (img == null) {

                img = (BufferedImage) createImage(size.width, size.height);

            }

            if (bufferG2D == null) {

                bufferG2D = img.createGraphics();

                bufferG2D.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_DEFAULT);

                bufferG2D.setClip(clippath);

            }

            g2d = bufferG2D;

            float[] ctrlpts;

            for (int i = 0; i < animpts.length; i += 2) {

                animate(animpts, deltas, i, size.width);

                animate(animpts, deltas, i + 1, size.height);

            }

            ctrlpts = animpts;

            int len = ctrlpts.length;

            gp.reset();

            float prevx = ctrlpts[len - 2];

            float prevy = ctrlpts[len - 1];

            float curx = ctrlpts[0];

            float cury = ctrlpts[1];

            float midx = (curx + prevx) / 2.0f;

            float midy = (cury + prevy) / 2.0f;

            gp.moveTo(midx, midy);

            for (int i = 2; i <= ctrlpts.length; i += 2) {

                float x1 = (midx + curx) / 2.0f;

                float y1 = (midy + cury) / 2.0f;

                prevx = curx;

                prevy = cury;

                if (i < ctrlpts.length) {

                    curx = ctrlpts[i];

                    cury = ctrlpts[i + 1];

                } else {

                    curx = ctrlpts[0];

                    cury = ctrlpts[1];

                }

                midx = (curx + prevx) / 2.0f;

                midy = (cury + prevy) / 2.0f;

                float x2 = (prevx + midx) / 2.0f;

                float y2 = (prevy + midy) / 2.0f;

                gp.curveTo(x1, y1, x2, y2, midx, midy);

            }

            gp.closePath();

            synchronized (lock) {

                g2d.setComposite(set);

                g2d.setBackground(getBezierColor(BACKGROUND));

                g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_OFF);

                // g2d.clearRect(bounds.x-5, bounds.y-5, bounds.x + bounds.width

                // + 5, bounds.y + bounds.height + 5);

                g2d.clearRect(0, 0, getWidth(), getHeight());

                g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

                g2d.setColor(getBezierColor(OUTER));

                g2d.setComposite(opaque);

                g2d.setStroke(solid);

                g2d.draw(gp);

                g2d.setPaint(gradient);

                Rectangle bounds = gp.getBounds();

                gradient = new GradientPaint(bounds.x, bounds.y, getBezierColor(GRADIENT_A), bounds.x + bounds.width,

                        bounds.y + bounds.height, getBezierColor(GRADIENT_B), true);

                g2d.setComposite(blend);

                g2d.fill(gp);

            }

            try {

                SwingUtilities.invokeAndWait(new Runnable() {

                    @Override

                    public void run() {

                        repaint();

                    }

                });

            } catch (InvocationTargetException | InterruptedException e) {

                e.printStackTrace();

            }

        }

        if (g2d != null) {

            g2d.dispose();

        }

    }

    public void paint(Graphics g) {

        synchronized (lock) {

            Graphics2D g2d = (Graphics2D) g;

            if (img != null) {

                g2d.setComposite(AlphaComposite.Src);

                g2d.drawImage(img, null, 0, 0);

            }

        }

    }