J2ME游戏开发技巧

public class BlocksCanvas extends Canvas implements Runnable
{
 Graphics bg;
 Image buf;
 public BlocksCanvas()
 {
  ......
  height = getHeight();
  width = getWidth();
  //按屏幕大小建立缓冲对象
  buf = Image.createImage(width, height);
  //将缓冲对象的Graphics附给bg
  bg = buf.getGraphics();
  ......
 }    
 public void run()
 {......
  for(i=0;i<ROWS;i++)
  {
   for(j=0;j<COLS;j++)
   {//画方块
    drawBlock(x,y);
   }
  }
  repaint();
 }
 private void drawBlock(int block_x, int block_y)
 {   
  //取得方块的坐标
  int x = getLeft(block_x);
  int y = getTop(block_y);
  //取得方块的颜色
  int c= board[block_x][block_y];   
  bg.drawImage(imgs[c], x, y, Graphics.TOP | Graphics.LEFT);
 }
 public void paint(Graphics g)
 {
  g.drawImage(buf, 0, 0, Graphics.TOP | Graphics.LEFT);
 }
      }

public class BlocksCanvas extends Canvas implements Runnable
{
 private boolean stopFlag=false;//调试标志
 ......
 public void run()
 {
  //断点位置1
  testFun(“x:”+x+“y:”+y);
  ......
  //断点位置2
  testFun(“”);
  ......
 }
 private void testFun(String str)
 {  
  stopFlag=true;
  //画一个白色长方形
  bg.setGrayScale(255);
  bg.fillRect(0,0, fontW, fontH);
  //在白色长方形上显示str的内容
  bg.setGrayScale(0);
  bg.drawString(str, 0,0, Graphics.TOP | Graphics.LEFT);
  repaint();
  while(stopFlag){}
 }
 public void keyPressed(int keyCode)
 {   
  stopFlag=false;
 } 
      }