import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

/**
 * This panel displays several copies of a message.  The color and 
 * position of each message is selected at random.  The font
 * of each message is randomly chosen from among five possible
 * fonts.  The messages are displayed on a black background.
 * The program uses an array to store the information needed
 * to draw the strings.
 * 
 * This class also contains a main() routine so that it can be run
 * as a program.
 * @author David J. Eck
 */
public class RandomStringsWithArray extends JPanel {

    /**
     * This main routine makes it possible to run RandomStringsWithArray
     * as a program.  When it is run, it creates a window that contains a
     * RandomStringsWithArray as its content pane.
     */
    public static void main(String[] args) {
        JFrame window = new JFrame("Hello World");
        RandomStringsWithArray content = new RandomStringsWithArray("Hello!");
        window.setContentPane(content);
        window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        window.setLocation(120,70);
        window.setSize(350,250);
        window.setVisible(true);
    }

    
    //----------------------------------------------------------------------------
    
    /**
     * An object of this type holds the position, color, and font
     * of one copy of the string.
     */
    private static class StringData {
       int x, y;     // The coordinates of the left end of baseline of string.
       Color color;  // The color in which the string is drawn.
       Font font;    // The font that is used to draw the string.
    }
    
    private final int MESSAGE_COUNT = 25;
    
    private String message;  // The message to be displayed.  This can be set in
                             // the constructor.  If no value is provided in the
                             // constructor, then the string "Java!" is used.

    private Font[] fonts; // An array to hold the five fonts that are available.
    
    private StringData[] stringData;  // Holds the data for drawing all the strings.

    /**
     * Default constructor creates a panel that displays the message "Java!".
     */
    public RandomStringsWithArray() {
        this(null);  // Call the other constructor, with parameter null.
    }

    /**
     * Constructor creates a panel to display 25 copies of a specified message.
     * @param messageString The message to be displayed.  If this is null,
     * then the default message "Java!" is displayed.
     */
    public RandomStringsWithArray(String messageString) {

        message = messageString;
        if (message == null)
            message = "Java!";

        fonts = new Font[5];  // Create the array to hold the five fonts.
         
        fonts[0] = new Font("Serif", Font.BOLD, 14);
        fonts[1] = new Font("SansSerif", Font.BOLD + Font.ITALIC, 24);
        fonts[2] = new Font("Monospaced", Font.PLAIN, 20);
        fonts[3] = new Font("Dialog", Font.PLAIN, 30);
        fonts[4] = new Font("Serif", Font.ITALIC, 36);
        
        setBackground(Color.BLACK);
        
        addMouseListener( new MouseAdapter() {
            public void mousePressed(MouseEvent evt) {
                   // In response to a mouse click, create new data for the strings,
                   // and call repaint to apply the change to what is shown on screen.
                createStringData();
                repaint();
            }
        });
        
    }
    
    /**
     * Creates the stringData array with random data that will be used to draw
     * the strings.  This method will be called from paintComponent to create the
     * first set of data.  It is also called by a MouseListener in response 
     * to a mouse click on the panel, so that the click will result in a
     * new set of data.  Note:  This method cannot be called from the constructor
     * since the width and height of the panel are not known when the constructor
     * is called, and the width and height are used in computing the coordinates
     * for the positions of the strings.
     */
    private void createStringData() {
        int width = getWidth();
        int height = getHeight();
        stringData = new StringData[MESSAGE_COUNT];
        for (int i = 0; i < MESSAGE_COUNT; i++) {
                // Create an object to represent the data for string number i,
                // and fill it with random values.
            stringData[i] = new StringData();
            int fontIndex = (int)(Math.random() * 5);
            stringData[i].font = fonts[fontIndex]; // one of 5 fonts, selected at random
            float hue = (float)Math.random();
            stringData[i].color = Color.getHSBColor(hue, 1.0F, 1.0F);  // random color
            stringData[i].x = -50 + (int)(Math.random()*(width+40));  // random x-coord
            stringData[i].y = (int)(Math.random()*(height+20));  // random y-coord
        }
    }

    /**
     * The paintComponent method is responsible for drawing the content of the panel.
     * It draws 25 copies of the message string, using a random color, font, and
     * position for each string.
     */
    public void paintComponent(Graphics g) {

        super.paintComponent(g);  // Call the paintComponent method from the 
                                  // superclass, JPanel.  This simply fills the 
                                  // entire panel with the background color, black.
        
        Graphics2D g2 = (Graphics2D)g;
        g2.setRenderingHint( RenderingHints.KEY_ANTIALIASING, 
                                RenderingHints.VALUE_ANTIALIAS_ON );
        
        if ( stringData == null ) {
                // If the data for the strings has not already been created, do it now.
                // This will only be the case the first time paintComponent() is called.
            createStringData();
        }

        for (int i = 0; i < MESSAGE_COUNT; i++) {
            g.setFont( stringData[i].font );
            g.setColor( stringData[i].color );
            g.drawString( message, stringData[i].x, stringData[i].y );

        } // end for

    } // end paintComponent()


}  // end class RandomStringsWithArray