/* CoordinatesDemo.java is a 1.4 application that requires no other files. */import javax.swing.*;import java.awt.*;import java.awt.event.MouseEvent;import javax.swing.event.MouseInputListener;/*  * This displays a framed area.  As the user moves the cursor * over the area, a label displays the cursor's location. When  * the user clicks, the area displays a 7x7 dot at the click * location. */public class CoordinatesDemo {    private JLabel label;    private Point clickPoint, cursorPoint;    private void buildUI(Container container) {        container.setLayout(new BoxLayout(container,                                          BoxLayout.PAGE_AXIS));        CoordinateArea coordinateArea = new CoordinateArea(this);        container.add(coordinateArea);        label = new JLabel();        resetLabel();        container.add(label);        //Align the left edges of the components.        coordinateArea.setAlignmentX(Component.LEFT_ALIGNMENT);        label.setAlignmentX(Component.LEFT_ALIGNMENT); //redundant    }    public void updateCursorLocation(int x, int y) {        if (x < 0 || y < 0) {            cursorPoint = null;            updateLabel();            return;        }                    if (cursorPoint == null) {            cursorPoint = new Point();        }                cursorPoint.x = x;        cursorPoint.y = y;        updateLabel();    }    public void updateClickPoint(Point p) {        clickPoint = p;        updateLabel();    }    public void resetLabel() {        cursorPoint = null;        updateLabel();            }        protected void updateLabel() {        String text = "";        if ((clickPoint == null) && (cursorPoint == null)) {            text = "Click or move the cursor within the framed area.";        } else {                        if (clickPoint != null) {                text += "The last click was at ("                         + clickPoint.x + ", " + clickPoint.y + "). ";            }                        if (cursorPoint != null) {                text += "The cursor is at ("                        + cursorPoint.x + ", " + cursorPoint.y + "). ";            }        }                label.setText(text);    }    /**     * Create the GUI and show it.  For thread safety,      * this method should be invoked from the      * event-dispatching thread.     */    private static void createAndShowGUI() {        //Make sure we have nice window decorations.        JFrame.setDefaultLookAndFeelDecorated(true);        //Create and set up the window.        JFrame frame = new JFrame("CoordinatesDemo");        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);        //Set up the content pane.        CoordinatesDemo controller = new CoordinatesDemo();        controller.buildUI(frame.getContentPane());        //Display the window.        frame.pack();        frame.setVisible(true);    }    public static void main(String[] args) {        //Schedule a job for the event-dispatching thread:        //creating and showing this application's GUI.        javax.swing.SwingUtilities.invokeLater(new Runnable() {            public void run() {                createAndShowGUI();             }        });    }    public static class CoordinateArea extends JComponent                                        implements MouseInputListener {        Point point = null;        CoordinatesDemo controller;        Dimension preferredSize = new Dimension(400,75);        Color gridColor;            public CoordinateArea(CoordinatesDemo controller) {            this.controller = controller;                        //Add a border of 5 pixels at the left and bottom,            //and 1 pixel at the top and right.            setBorder(BorderFactory.createMatteBorder(1,5,5,1,                                                      Color.RED));                                                                  addMouseListener(this);            addMouseMotionListener(this);            setBackground(Color.WHITE);            setOpaque(true);        }            public Dimension getPreferredSize() {            return preferredSize;        }            protected void paintComponent(Graphics g) {            //Paint background if we're opaque.            if (isOpaque()) {                g.setColor(getBackground());                g.fillRect(0, 0, getWidth(), getHeight());            }            //Paint 20x20 grid.            g.setColor(Color.GRAY);            drawGrid(g, 20);                        //If user has chosen a point, paint a small dot on top.            if (point != null) {                g.setColor(getForeground());                g.fillRect(point.x - 3, point.y - 3, 7, 7);            }        }                //Draws a 20x20 grid using the current color.        private void drawGrid(Graphics g, int gridSpace) {            Insets insets = getInsets();            int firstX = insets.left;            int firstY = insets.top;            int lastX = getWidth() - insets.right;            int lastY = getHeight() - insets.bottom;                        //Draw vertical lines.            int x = firstX;            while (x < lastX) {                g.drawLine(x, firstY, x, lastY);                x += gridSpace;            }                        //Draw horizontal lines.            int y = firstY;            while (y < lastY) {                g.drawLine(firstX, y, lastX, y);                y += gridSpace;            }        }            //Methods required by the MouseInputListener interface.        public void mouseClicked(MouseEvent e) {             int x = e.getX();            int y = e.getY();            if (point == null) {                point = new Point(x, y);            } else {                point.x = x;                point.y = y;            }            controller.updateClickPoint(point);            repaint();        }        public void mouseMoved(MouseEvent e) {            controller.updateCursorLocation(e.getX(), e.getY());        }        public void mouseExited(MouseEvent e) {             controller.resetLabel();        }        public void mouseReleased(MouseEvent e) { }        public void mouseEntered(MouseEvent e) { }        public void mousePressed(MouseEvent e) { }        public void mouseDragged(MouseEvent e) { }    }}