hitpighead.java

Java2游戏编程源码 第四章 很好的学习Java和简单游戏编程的书籍

// 程序：游戏开头画面
// 范例文件：HitPigHead.java

import java.awt.*;
import java.util.*; 
import java.applet.*;

class StartScreen   
{

   int     width,height,StringWidth,StringHeight,Ascent,Descent,X,Y;
   int     ImageLeftBound,ImageRightBound,ImageX,ImageY,ImageWidth,
           ImageHeight,VX;
   Font    F1,F2,F3;
   Image   Normal,bkImage,Hit,currentImage;
   String  ChineseTitle,EnglishTitle,PressEnter;
   HitPigHead  Game;
   Random  R;
   boolean showPressEnter;

   FontMetrics FM;

   public StartScreen(int AppletWidth,int AppletHeight,HitPigHead Game,
                      Image normal,Image hit, Image bk)
   {
      R      = new Random();   

      F1     = new Font("TimesRoman",Font.BOLD,72);
      F2     = new Font("TimesRoman",Font.BOLD + Font.ITALIC,36);
      F3     = new Font("TimesRoman",Font.BOLD,20);

      ChineseTitle    = "棒打猪头";            
      EnglishTitle    = "Hit Pig's Head";     
      PressEnter      = "<<<==请按Enter键开始游戏==>>>"; 

      width           = AppletWidth;          
      height          = AppletHeight;        

      Normal          = normal; 
      Hit             = hit;    
      bkImage         = bk;     
 
      ImageWidth      = Normal.getWidth(Game);  
      ImageHeight     = Normal.getHeight(Game); 
      ImageLeftBound  = 25;                     
      ImageRightBound = AppletWidth - (25 + ImageWidth); 
      ImageX          = ImageRightBound;        
 
      VX              = -3;     
      this.Game       = Game;
      currentImage    = Normal; 
      showPressEnter  = true;  
   }

   public void UpdateStatus()    
   {
      ImageX = ImageX + VX;        

      if(ImageX <= ImageLeftBound) 
      {
         currentImage = Hit;     

         ImageX = ImageLeftBound; 
         VX     = -VX;           
      }

      if(ImageX >= ImageRightBound)
      {
         currentImage = Normal;    

         ImageX = ImageRightBound;  
         VX     = -VX;           
      }

      if(showPressEnter == true)
      {
         if((R.nextInt(5) + 1) % 5 == 0)
            showPressEnter = false;
      }
      else
      {
         if((R.nextInt(5) + 1) % 5 == 0)
            showPressEnter = true;
      }
   }

   public void paintScreen(Graphics g)  
   {
      g.clearRect(0,0,width,height);    

      g.setFont(F1);                  
      FM = g.getFontMetrics();

      Ascent       = FM.getAscent();
      Descent      = FM.getDescent();
      StringWidth  = FM.stringWidth(ChineseTitle);
      StringHeight = Ascent + Descent; 
      
      X            = (width - StringWidth) / 2;
      Y            = Ascent;
 
      g.drawImage(bkImage, 0, 0, Game);
      g.setColor(Color.white);         
      g.drawString(ChineseTitle,X,Y);   

      Y            = StringHeight;
      g.drawLine(X,Y,X+StringWidth,Y);  

      X            = X + 30;
      Y            = Y + 5;
      g.drawLine(X,Y,X+StringWidth-60,Y);

      g.setFont(F2);                 
      FM = g.getFontMetrics();

      Ascent       = FM.getAscent();
      Descent      = FM.getDescent();
      StringWidth  = FM.stringWidth(EnglishTitle);
      StringHeight = Ascent + Descent; 

      X            = (width - StringWidth) / 2;
      Y            = Y + Ascent;
      g.drawString(EnglishTitle,X,Y);  

      ImageY       = Y + Descent + 30; 
      g.drawImage(currentImage,ImageX,ImageY,Game);

      g.setFont(F3);               
      FM = g.getFontMetrics();

      Ascent       = FM.getAscent();
      Descent      = FM.getDescent();
      StringWidth  = FM.stringWidth(PressEnter);
      StringHeight = Ascent + Descent; 

      X            = (width - StringWidth) / 2;
      Y            = ImageY + ImageHeight + Ascent + 30;

      if(showPressEnter)
         g.drawString(PressEnter,X,Y); 
   }
}

public class HitPigHead extends Applet implements Runnable
{
  
   int          AppletWidth,AppletHeight;
   Image        OffScreen,bkImage,PigHead_Normal,PigHead_Hit;
   Thread       newThread;
   Graphics     drawOffScreen;
   StartScreen  S_Screen;
   MediaTracker MT;


   public void init()
   {
      setBackground(Color.black);    


      PigHead_Normal = getImage(getDocumentBase(),"Images/pig1.gif");
      PigHead_Hit    = getImage(getDocumentBase(),"Images/pig2.gif");
      bkImage        = getImage(getDocumentBase(),"Images/009.jpg");
      
      MT = new MediaTracker(this);
      MT.addImage(PigHead_Normal,0);
      MT.addImage(PigHead_Hit,0);

      try
      {
         showStatus("图像载入中(Loading Images)...");
         MT.waitForAll();
      }
      catch(InterruptedException E){ } 

      AppletWidth  = getSize().width;  
      AppletHeight = getSize().height;  

      S_Screen = new StartScreen(AppletWidth,AppletHeight,this,
                 PigHead_Normal,PigHead_Hit, bkImage);
            
      OffScreen     = createImage(AppletWidth,AppletHeight);
      drawOffScreen = OffScreen.getGraphics();
   }

   public void start()           
   {
      newThread = new Thread(this); 
      newThread.start();
   }

   public void stop()      
   {
      newThread = null;   
   }

   public void paint(Graphics g)
   {

      if((MT.statusAll(false) & MediaTracker.ERRORED)  != 0)
      {
         FontMetrics FM = g.getFontMetrics();

         int Ascent      = FM.getAscent();
         int Descent     = FM.getDescent();
         int StringWidth = FM.stringWidth("载入图像发生错误...");

         int X = (AppletWidth - StringWidth) / 2;
         int Y = (AppletHeight - (Ascent + Descent)) / 2 + Ascent;

         g.setColor(Color.white);           
         g.drawString("载入图像发生错误...",X,Y); 

         return;                
      }   


      S_Screen.paintScreen(drawOffScreen);


      g.drawImage(OffScreen,0,0,this);
   }

   public void update(Graphics g)   
   {
      paint(g);                    
   }
   
   public void run()
   {  
      while(newThread != null)   
      {  
         repaint();              

         try
         {
            Thread.sleep(80);       
         }
         catch(InterruptedException E){ }
       
         S_Screen.UpdateStatus();    
      }
   }
}