[Android实例] android多点触摸demo

public class MultiTouchActivity extends Activity {  
    /** Called when the activity is first created. */ 
     /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) {  
      super.onCreate(savedInstanceState);            
      //隐藏标题栏            
      requestWindowFeature(Window.FEATURE_NO_TITLE);            
      //设置成全屏           
      getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN);            
      //设置为上面的MTView            
      setContentView(new MySurfaceView(this));    
    }  
} 




import android.content.Context;  
import android.graphics.Canvas;  
import android.graphics.Color;  
import android.graphics.Paint;  
import android.view.MotionEvent;  
import android.view.SurfaceHolder;  
import android.view.SurfaceHolder.Callback;  
import android.view.SurfaceView;  
public class MySurfaceView extends SurfaceView implements Callback{  
private static final int MAX_TOUCHPOINTS = 10;  
private static final String START_TEXT = "请随便触摸屏幕进行测试";        
private Paint textPaint = new Paint();        
private Paint touchPaints[] = new Paint[MAX_TOUCHPOINTS];        
private int colors[] = new int[MAX_TOUCHPOINTS];           
private int width, height;        
private float scale = 1.0f;  
 
public MySurfaceView(Context context) {  
  super(context);  
  SurfaceHolder holder = getHolder();            
  holder.addCallback(this);            
  setFocusable(true); // 确保我们的View能获得输入焦点            
  setFocusableInTouchMode(true); // 确保能接收到触屏事件            
  init();    
}  
public void init(){  
  // 初始化10个不同颜色的画笔            
  textPaint.setColor(Color.WHITE);    
  colors[0] = Color.BLUE;    
  colors[1] = Color.RED;  
  colors[2] = Color.GREEN;  
  colors[3] = Color.YELLOW;  
  colors[4] = Color.CYAN;  
  colors[5] = Color.MAGENTA;  
  colors[6] = Color.DKGRAY;  
  colors[7] = Color.WHITE;  
  colors[8] = Color.LTGRAY;  
  colors[9] = Color.GRAY;  
  for(int i=0;i<MAX_TOUCHPOINTS;i++){  
   touchPaints[i]=new Paint();  
   touchPaints[i].setColor(colors[i]);  
  }  
}  
 
@Override 
public boolean onTouchEvent(MotionEvent event) {  
  int pointerCount=event.getPointerCount();  
  if(pointerCount>MAX_TOUCHPOINTS){  
   pointerCount=MAX_TOUCHPOINTS;  
  }  
  Canvas c=getHolder().lockCanvas();  
  if(c!=null){  
   c.drawColor(Color.BLACK);  
   if(event.getAction()==MotionEvent.ACTION_UP){  
    // 当手离开屏幕时，清屏  
    c.drawColor(Color.BLACK);  
   }else{  
     // 先在屏幕上画一个十字，然后画一个圆  
    for(int i=0;i<pointerCount;i++){  
     //获取一个触点的坐标，然后开始绘制  
     int id=event.getPointerId(i);  
     int x=(int)event.getX(i);  
     int y=(int)event.getY(i);  
     drawCrosshairsAndText(x, y, touchPaints[id], i, id, c);  
    }  
    for(int i=0;i<pointerCount;i++){  
     int id=event.getPointerId(i);  
     int x=(int)event.getX(i);  
     int y=(int)event.getY(i);  
     drawCircle(x, y, touchPaints[id],c);  
    }  
   }  
   getHolder().unlockCanvasAndPost(c);  
  }  
  return true;  
}  
 
private void drawCrosshairsAndText(int x, int y, Paint paint, int ptr,int id, Canvas c) {  
  c.drawLine(0, y, width, y, paint);            
  c.drawLine(x, 0, x, height, paint);            
  int textY = (int) ((15 + 20 * ptr) * scale);            
  c.drawText("x" + ptr + "=" + x, 10 * scale, textY, textPaint);            
  c.drawText("y" + ptr + "=" + y, 70 * scale, textY, textPaint);            
  c.drawText("id" + ptr + "=" + id, width - 55 * scale, textY, textPaint);     
}    
 
private void drawCircle(int x, int y, Paint paint, Canvas c) {  
  c.drawCircle(x, y, 40 * scale, paint);        
}    
 
@Override 
public void surfaceChanged(SurfaceHolder holder, int format, int width,  
   int height) {  
   this.width = width;            
   this.height = height;            
   if (width > height){                
    this.scale = width / 480f;            
   } else {  
   this.scale = height / 480f;            
   }            
   textPaint.setTextSize(14 * scale);            
   Canvas c = getHolder().lockCanvas();            
   if (c != null) {              // 背景黑色                
    c.drawColor(Color.BLACK);                
    float tWidth = textPaint.measureText(START_TEXT);                
    c.drawText(START_TEXT, width / 2 - tWidth / 2, height / 2,textPaint);                
    getHolder().unlockCanvasAndPost(c);            
  }    
}  
@Override 
public void surfaceCreated(SurfaceHolder holder) {  
  // TODO Auto-generated method stub  
    
}  
@Override 
public void surfaceDestroyed(SurfaceHolder holder) {  
  // TODO Auto-generated method stub  
    
}   
 
}