Painting in only one panel?

Question

Hello,
I need to make a joystick style gui part in my applet, but only in one panel of the applet, Is it possible to paint in just one panel, and if so, can you point me in the right direction? Or even better, is there a joystick style swing component i dont know about? it basically just needs to be a slider with x and y components. Also, Would using a custom synth look and feel screw up any painting im trying to do? Thanks beforehand.
Cheers.

Answer 1

Andre_Uhres wrote:
I don't know about any "joystick style swing component" and I couldn't even tell you how to develop such a component.So I searched the web. This article might be helpful: [Virtual joystick GUI|http://www.freepatentsonline.com/6515687.html]. Logical Processing for the Virtual Joystick is summarized in the pseudo-code of TABLE 1.
Edited by: Andre_Uhres on Jan 30, 2010 11:35 AM
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class SimpleJoystickDemo extends JFrame {
    private int displayWidth = 340;
    private int displayHeight = 550;
    private final Point position;
    public SimpleJoystickDemo() {
        super("SimpleJoystickDemo");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(displayWidth, displayHeight);
        setLocationRelativeTo(null);
        position = new Point();
        SimpleJoystick myJoystick = new SimpleJoystick(150, position, 100);
        add(myJoystick, BorderLayout.PAGE_END);
        Drawing drawing = new Drawing(position);
        add(drawing);
    public static void main(final String[] args) {
        Runnable gui = new Runnable() {
            public void run() {
                new SimpleJoystickDemo().setVisible(true);
        //GUI must start on EventDispatchThread:
        SwingUtilities.invokeLater(gui);
    class Drawing extends JPanel {
        private final Point position;
        public Drawing(Point position) {
            this.position = position;
        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2 = (Graphics2D) g;
            g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                    RenderingHints.VALUE_ANTIALIAS_ON);
            g2.setColor(Color.RED);
            g2.fillOval(160 + position.x, 160 - position.y, 15, 15);
class SimpleJoystick extends JPanel {
    //Maximum value for full horiz or vert position where centered is 0:
    private int joyOutputRange;
    private float joySize;     //joystick icon size
    private float joyWidth, joyHeight;
    private float joyCenterX, joyCenterY;  //Joystick displayed Center
    //Display positions for text feedback values:
    private int textHorizPos, textVertPos;
    private int fontSpace = 12;
    private float curJoyAngle;    //Current joystick angle
    private float curJoySize;     //Current joystick size
    private boolean isMouseTracking;
    private boolean leftMouseButton;
    private int mouseX, mouseY;
    private Stroke lineStroke = new BasicStroke(10,
            BasicStroke.CAP_ROUND, BasicStroke.JOIN_ROUND);
    private final Point position;
    public SimpleJoystick(final int joyOutputRange, final Point position,
            final int joySize) {
        this.joyOutputRange = joyOutputRange;
        this.position = position;
        this.joySize = joySize;
        joyWidth = joySize;
        joyHeight = joyWidth;
        setPreferredSize(new Dimension((int) joyWidth + 250,
                (int) joyHeight + 80));
        joyCenterX = getPreferredSize().width / 2;
        joyCenterY = getPreferredSize().height / 2;
        this.joySize = joyWidth / 2;
        setBackground(new Color(226, 226, 226));
        MouseAdapter mouseAdapter = new MouseAdapter() {
            @Override
            public void mouseMoved(final MouseEvent e) {
                mouseCheck(e);
            @Override
            public void mousePressed(final MouseEvent e) {
                leftMouseButton = SwingUtilities.isLeftMouseButton(e);
                mouseCheck(e);
        addMouseMotionListener(mouseAdapter);
        addMouseListener(mouseAdapter);
    private void mouseCheck(final MouseEvent e) {
        mouseX = e.getX();
        mouseY = e.getY();
        float dx = mouseX - joyCenterX;
        float dy = mouseY - joyCenterY;
        if (leftMouseButton) {
            isMouseTracking = true;
        } else {
            isMouseTracking = false;
        if (isMouseTracking) {
            curJoyAngle = (float) Math.atan2(dy, dx);
            curJoySize = (float) Point.distance(mouseX, mouseY,
                    joyCenterX, joyCenterY);
        } else {
            curJoySize = 0;
        if (curJoySize > joySize) {
            curJoySize = joySize;
        position.x = (int) (joyOutputRange * (Math.cos(curJoyAngle)
                * curJoySize) / joySize);
        position.y = (int) (joyOutputRange * (-(Math.sin(curJoyAngle)
                * curJoySize) / joySize));
        SwingUtilities.getRoot(SimpleJoystick.this).repaint();
    @Override
    protected void paintComponent(final Graphics g) {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D) g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                RenderingHints.VALUE_ANTIALIAS_ON);
        g2.setColor(Color.LIGHT_GRAY);
        g2.fillOval((int) (joyCenterX - joyWidth / 2),
                (int) (joyCenterY - joyHeight / 2),
                (int) joyWidth, (int) joyHeight);
        //rotate and draw joystick line segment:
        Graphics2D g3 = (Graphics2D) g2.create();
        g3.translate(joyCenterX, joyCenterY);
        g3.rotate(curJoyAngle);
        g3.setColor(Color.GRAY);
        g3.setStroke(lineStroke);
        g3.drawLine(0, 0, (int) curJoySize, 0);
        g3.dispose();
        g2.setColor(Color.GRAY);
        g2.fillOval((int) joyCenterX - 10,
                (int) joyCenterY - 10, 20, 20);
        textHorizPos = 50;
        textVertPos = (int) (joyCenterY - 50);
        g2.drawString("Horiz:", textHorizPos, textVertPos);
        textHorizPos += (4 * fontSpace);
        g2.drawString(String.valueOf((int) position.x), textHorizPos,
                textVertPos);
        textHorizPos = 50;
        textVertPos += 12;
        g2.drawString("Vert:", textHorizPos, textVertPos);
        textHorizPos += (4 * fontSpace);
        g2.drawString(String.valueOf((int) position.y), textHorizPos,
                textVertPos);
}Edited by: Andre_Uhres on Feb 1, 2010 10:23 PM