Learn Java Now/Learn_Java_Now_Microsoft_1996.iso/JavaNow/Code/Chap14/Marquee/Marquee.java

Java Source | 1996-06-18 | 9.0 KB | 271 lines

//******************************************************************************
// Marquee.java:    Applet
//
//******************************************************************************
import java.applet.*;
import java.awt.*;

//==============================================================================
// Main Class for applet Marquee
//
//==============================================================================
public class Marquee extends Applet implements Runnable
{
    // THREAD SUPPORT:
    //        m_Marquee    is the Thread object for the applet
    //--------------------------------------------------------------------------
    Thread     m_Marquee = null;

    // PARAMETER SUPPORT:
    //        Parameters allow an HTML author to pass information to the applet;
    // the HTML author specifies them using the <PARAM> tag within the <APPLET>
    // tag.  The following variables are used to store the values of the
    // parameters.
    //--------------------------------------------------------------------------

    // Members for applet parameters
    // <type>       <MemberVar>    = <Default Value>
    //--------------------------------------------------------------------------
    String m_string = "";
    String m_font = "Courier";
    String m_style = "PLAIN";
    int m_size = 12;
    int m_fps = 10;

    // parameter names. to change the name of a parameter,
    // you need only make a single change. simply modify
    // the value of the parameter string below.
    //--------------------------------------------------------------------------
    final String PARAM_string = "string";
    final String PARAM_font = "font";
    final String PARAM_style = "style";
    final String PARAM_size = "size";
    final String PARAM_fps = "fps";

    // the following data members are used to keep track of the
    // minimum and maximum x offset of the text. This is what
    // makes the applet scroll.
    private int m_nOffset;
    private int m_nMax;
    private int m_nMin;

    // Marquee Class Constructor
    //--------------------------------------------------------------------------
    public Marquee()
    {
        // TODO: Add Constructor code here
    }

    // Marquee Class Destructor
    //--------------------------------------------------------------------------
    public void finalize()
    {
        // TODO: Add Destructor code here
    }

    // APPLET INFO SUPPORT:
    //        The getAppletInfo() method returns a string describing the applet's
    // author, copyright date, or miscellaneous information.
    //--------------------------------------------------------------------------
    public String getAppletInfo()
    {
        return "Name: Marquee\r\n" +
               "Author: Stephen R. Davis\r\n" +
               "Created for Learn Java Now (c)";
    }

    // PARAMETER SUPPORT
    //        The getParameterInfo() method returns an array of strings describing
    // the parameters understood by this applet.
    //
    // Marquee Parameter Information:
    //  { "Name", "Type", "Description" },
    //--------------------------------------------------------------------------
    public String[][] getParameterInfo()
    {
        String[][] info =
        {
            { PARAM_string, "String", "String to output in marquee" },
            { PARAM_font, "String", "Font to use" },
            { PARAM_style, "String", "PLAIN, BOLD, or ITALIC" },
            { PARAM_size, "int", "Font size [pts]" },
            { PARAM_fps, "int", "Frame rate" },
        };
        return info;
    }

    // The init() method is called by the AWT when an applet is first loaded or
    // reloaded.  Override this method to perform whatever initialization your
    // applet needs, such as initializing data structures, loading images or
    // fonts, creating frame windows, setting the layout manager, or adding UI
    // components.
    //--------------------------------------------------------------------------
    public void init()
    {
        // PARAMETER SUPPORT
        //        The following code retrieves the value of each parameter
        // specified with the <PARAM> tag and stores it in a member
        // variable.
        //----------------------------------------------------------------------
        String param;

        // string: String to output in marquee
        //----------------------------------------------------------------------
        param = getParameter(PARAM_string);
        if (param != null)
            m_string = param;

        // font: Font to use
        //----------------------------------------------------------------------
        param = getParameter(PARAM_font);
        if (param != null)
            m_font = param;

        // style: PLAIN, BOLD, or ITALIC
        //----------------------------------------------------------------------
        param = getParameter(PARAM_style);
        if (param != null)
            m_style = param;

        // size: Font size [pts]
        //----------------------------------------------------------------------
        param = getParameter(PARAM_size);
        if (param != null)
            m_size = Integer.parseInt(param);

        // fps: Frame rate
        //----------------------------------------------------------------------
        param = getParameter(PARAM_fps);
        if (param != null)
            m_fps = Integer.parseInt(param);

        // resize(600, 80);

        // create the font here based on the parameters entered
        int nStyle = Font.PLAIN;
        if (m_style.equalsIgnoreCase("BOLD"))
        {
            nStyle = Font.BOLD;
        }
        if (m_style.equalsIgnoreCase("ITALIC"))
        {
            nStyle = Font.ITALIC;
        }

        Font font = new Font(m_font, nStyle, m_size);

        // now make this the font for this applet's window
        setFont(font);

        // now calculate the size of the string in the current
        // font. use this information to set the minimum and
        // maximum x offset.
        // calculate the left boundary by measuring the
        // size of the message in the current font.
        FontMetrics fm = getFontMetrics(font);
        m_nMin = -fm.stringWidth(m_string);

        // the right margin is the width of the window
        m_nMax = size().width;

        // now start the string at the far right of the window
        m_nOffset  = m_nMax;

        // TODO: Place Addition Initialization code here
    }

    // Place additional applet clean up code here.  destroy() is called when
    // when you applet is terminating and being unloaded.
    //-------------------------------------------------------------------------
    public void destroy()
    {
        // TODO: Place applet cleanup code here
    }

    // Marquee Paint Handler
    //--------------------------------------------------------------------------
    public void paint(Graphics g)
    {
        int nVertOffset = size().height;
        nVertOffset = (nVertOffset - m_size) / 2;
        g.drawString(m_string, m_nOffset, nVertOffset + m_size);

        // now decrement the offset so that the next
        // time the string will appear one pixel to the left
        // (once the entire string has scrolled off to the left,
        // restart it at the far right)
        m_nOffset--;
        if (m_nOffset < m_nMin)
        {
            m_nOffset = m_nMax;
        }
    }

    //        The start() method is called when the page containing the applet
    // first appears on the screen. The AppletWizard's initial implementation
    // of this method starts execution of the applet's thread.
    //--------------------------------------------------------------------------
    public void start()
    {
        if (m_Marquee == null)
        {
            m_Marquee = new Thread(this);
            m_Marquee.start();
        }
        // TODO: Place additional applet Start code here
    }

    //        The stop() method is called when the page containing the applet is
    // no longer on the screen. The AppletWizard's initial implementation of
    // this method stops execution of the applet's thread.
    //--------------------------------------------------------------------------
    public void stop()
    {
        if (m_Marquee != null)
        {
            m_Marquee.stop();
            m_Marquee = null;
        }

        // TODO: Place additional applet Stop code here
    }

    // THREAD SUPPORT
    //        The run() method is called when the applet's thread is started. If
    // your applet performs any ongoing activities without waiting for user
    // input, the code for implementing that behavior typically goes here. For
    // example, for an applet that performs animation, the run() method controls
    // the display of images.
    //--------------------------------------------------------------------------
    public void run()
    {
        while (true)
        {
            // calculate the sleep time based on the frames
            // per second. sleep time is in units of
            // milliseconds.
            int nSleepValue = 1000 / m_fps;
            try
            {
                // repaint the window every nSleepValue
                // milliseconds
                repaint();
              // Thread.sleep(50); // we don't want the default
                Thread.sleep(nSleepValue);
            }
            catch (InterruptedException e)
            {
                // TODO: Place Exception handling code here in case an
                //       InterruptedException is thrown by Thread.sleep(),
                //         meaning that another thread has interrupted this one
                stop();
            }
        }
    }



    // TODO: Place additional applet Code here

}