nervousscrolltext.java

Java 范例实战 光盘使用说明 ========================== 本光盘的文件结构如下所示： =====================================

import java.applet.Applet;
import java.applet.AudioClip;
import java.awt.*;

public class NervousScrollText extends Applet implements Runnable
{

    Image offScreen ;
    Graphics offScreenG ;
    Thread scroller ;
    final static String DEFAULT_TEXT = 
    			"ABCDEFGHIJKLMNOPQRSTUVWXYZ+-*/" ;
    String text ;
    int[] letterWidth, pseudoRandom ;
    int maxCharWidth, width, height,
        scrollIncrement, letterPos, pos, baseY, 
        mouseDistortionX0, mouseDistortionX1,
        randomCounter, direction, firstCharIndex, 
        firstCharPos, sleepingTime ;
    boolean nervous, isPlaying, hasShadow ;
    AudioClip nervousSound ;
    Color backColor, textColor ;
    Point shadowDis ;

    public NervousScrollText()
    {
        
        isPlaying = false;
        hasShadow = true;
        shadowDis = new Point(3, 3);
    
    }

    int getParameter(String s1, int s2) 
    {
    
        String s = getParameter(s1) ;
        return (s != null) ? Integer.parseInt(s) : s2 ;
    
    }

    String getParameter(String s1, String s2) 
    {
    
        String s = getParameter(s1) ;
        return (s != null) ? s : s2 ;
    
    }

    public void init()
    {
    
        text = getParameter("message", DEFAULT_TEXT) + " " ;
        backColor = new Color(Integer.parseInt(
        		getParameter("back_color", "000000"), 16));
        textColor = new Color(Integer.parseInt(
        		getParameter("text_color", "00ff00"), 16));
        direction = getParameter("direction", 1);

        scrollIncrement = getParameter("scroll_increment", 4);
        if(scrollIncrement == 0) scrollIncrement = 1 ;
        if(scrollIncrement < 0)
        {

            direction = -direction;
            scrollIncrement = -scrollIncrement;

        }

        sleepingTime = getParameter("sleeping_time", 100);
        if(sleepingTime <= 0) sleepingTime = 100;
        String s = getParameter("nervous");
        if(s == null) nervous = false;
        else nervous = true ;
        if(nervous)
            if(getParameter("audio") != null)
                nervousSound = getAudioClip(getCodeBase(), 
                		getParameter("audio"));
            else nervousSound = null;

        Font font = new Font(getParameter("font", "Helvetica"), 0, 
        		getParameter("font_size", 14));
        if(font != null) setFont(font);

        letterWidth = getGraphics().getFontMetrics().getWidths();
        maxCharWidth = 0;
        for(char c = '\0'; c < 128; c++)
            if(letterWidth[c] > maxCharWidth) 
            	maxCharWidth = letterWidth[c];

        pseudoRandom = new int[128];
        for(int j = 0; j < 128; j++)
            pseudoRandom[j] = (int)(Math.random() * 10D) - 5;

        offScreen = createImage(getSize().width + maxCharWidth * 2, 
        	    getSize().height);
        offScreenG = offScreen.getGraphics();
        if(font != null) offScreenG.setFont(font);
        int k = offScreenG.getFontMetrics().getHeight();
        int l = offScreenG.getFontMetrics().getDescent();
        baseY = ((getSize().height + k) - l) / 2;
        width = getSize().width ;
        height = getSize().height ;
        if(direction == 1)
        {
        
            firstCharIndex = 0;
            firstCharPos = width + maxCharWidth;
        
        }
        else
        {
        
            firstCharIndex = text.length() - 1;
            firstCharPos = 0;
        
        }
    
    }

    public void update(Graphics g)
    {
    
        int i = firstCharIndex;
        int j = firstCharPos;
        offScreenG.setColor(backColor);
        offScreenG.fillRect(0, 0, width + 2 * maxCharWidth, height);
        offScreenG.setColor(textColor);
        do
        {
    
            if(direction != 1 ? j < 0 : j > width + maxCharWidth) 
            	break;
            int k = baseY, l = j;
            if(j > mouseDistortionX0 && j < mouseDistortionX1)
            {
    
                l += pseudoRandom[randomCounter++];
                k += pseudoRandom[randomCounter++];
                randomCounter &= 0x7f;
    
            }
            char c = text.charAt(i);
            offScreenG.drawString(text.substring(i, i + 1), l, k);
            if(direction == 1)
            {
    
                j += letterWidth[c];
                if(++i == text.length()) i = 0;
    
            }
            else
            {
    
                if(--i == -1) i = text.length() - 1;
                j -= letterWidth[text.charAt(i)];
    
            }
    
        } while(true);

        if(direction == 1)
        {
        
            firstCharPos -= scrollIncrement;
            if(firstCharPos < 0)
            {
        
                firstCharPos += 
                	letterWidth[text.charAt(firstCharIndex)];
                firstCharIndex++;
                if(firstCharIndex == text.length()) 
                	firstCharIndex = 0;
            
            }
        
        }
        else
        {
        
            firstCharPos += scrollIncrement;
            if(firstCharPos > width + maxCharWidth)
            {
        
                firstCharIndex--;
                if(firstCharIndex == -1) 
                	firstCharIndex = text.length() - 1;
                firstCharPos -= 
                	letterWidth[text.charAt(firstCharIndex)];
        
            }
        
        }
        paint(g);
    
    }

    public void paint(Graphics g)
    {
    
        g.drawImage(offScreen, -maxCharWidth, 0, null);
    
    }

    public boolean mouseMove(Event event, int i, int j)
    {
    
        if(!nervous) return false;
        mouseDistortionX0 = i - maxCharWidth;
        mouseDistortionX1 = i + maxCharWidth;
        if(nervousSound != null && !isPlaying)
        {
    
            isPlaying = true;
            nervousSound.loop();
    
        }
        return true;
    
    }

    public boolean mouseExit(Event event, int i, int j)
    {
    
        if(!nervous) return false;
        mouseDistortionX0 = mouseDistortionX1 = 0;
        if(nervousSound != null)
        {
    
            nervousSound.stop();
            isPlaying = false;
    
        }
        return true;
    
    }

    public void stop()
    {
    
        scroller = null;
    
    }

    public void start()
    {
    
        if(scroller == null)
        {
    
            scroller = new Thread(this);
            scroller.start();
    
        }
    
    }

    public void run()
    {
    
        do
        {
    
            repaint();
            try
            {
    
                Thread.sleep(sleepingTime, 0);
    
            }
            catch(InterruptedException e) { }
    
        } while(true);
    
    }

}