screensavercanvas.java

来自「画布实现屏幕保护程序」· Java 代码 · 共 57 行

import javax.microedition.lcdui.*;
import javax.microedition.midlet.*;
import java.util.*;

public  class ScreenSaverCanvas extends Canvas implements CommandListener{
     private Command cmExit;
     private Command cmClear;

     protected int startX = 0,
                     startY = 0,
                     endX = 0,
                     endY = 0;
     private ScreenSaver midlet;
     private boolean clearDisplay = false;

     protected int linesDrawn = 0;

     private static final int MAX_LINES =100;

     public ScreenSaverCanvas (ScreenSaver midlet){
         this.midlet = midlet;
         cmExit = new Command("EXIT",Command.EXIT ,1);
         cmClear = new Command("CLEAR",Command.SCREEN ,2);
         addCommand(cmExit);
         addCommand(cmClear);

         setCommandListener(this);

     }
     protected void paint(Graphics g){
         if(clearDisplay || linesDrawn >MAX_LINES){
             g.setColor(255,255,255);
             g.fillRect(0,0,getWidth(),getHeight());
             startX = endX = startY = endY = 0;
             clearDisplay = false;
             linesDrawn = 0;

             return;

         }

         g.setColor(0,0,0);
         g.drawLine(startX,startY,endX,endY);
         startX = endX;
         startY = endY;

     }
     public void commandAction(Command c,Displayable d){
         if(c == cmExit){
             midlet.exitMIDlet();

         }else if(c == cmClear){
             clearDisplay = true;
             repaint();
         }
     }
}