WindowManager实现悬浮窗口

调用WindowManager，并设置WindowManager.LayoutParams的相关属性，通过WindowManager的addView方法创建View，这样产生出来的View根据WindowManager.LayoutParams属性不同，效果也就不同了。比如创建系统顶级窗口，实现悬浮窗口效果！ 需要特别说明的是，在MIUI系统上面，悬浮框默认是不显示的，需要到设置-应用程序里面找到应用信息，打开显示悬浮窗选项。
WindowManager的方法很简单，基本用到的就三个addView，removeView，updateViewLayout。 


而WindowManager.LayoutParams的属性就多了，非常丰富，具体请查看SDK文档。这里给出Android中的WindowManager.java源码，可以具体看一下。 
WindowManager 的源码地址： 
http://www.netmite.com/android/mydroid/frameworks/base/core/java/android/view/WindowManager.java 

public class myFloatView extends Activity {  
    /** Called when the activity is first created. */  
    @Override  
    public void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.main);  
        Button bb=new Button(getApplicationContext());  
        WindowManager wm=(WindowManager)getApplicationContext().getSystemService("window");  
        WindowManager.LayoutParams wmParams = new WindowManager.LayoutParams();  
        //wmParams.type=2002;  //type是关键，这里的2002表示系统级窗口，你也可以试试2003。 
		wmParams.type=LayoutParams.TYPE_PHONE;
		//wmParams.format=PixelFormat.RGBA_8888;   //设置图片格式，效果为背景透明
        wmParams.format=1;  
       
		wmParams.flags=LayoutParams.FLAG_NOT_TOUCH_MODAL  
                             | LayoutParams.FLAG_NOT_FOCUSABLE;  
       /* 
        * 下面的flags属性的效果形同“锁定”。 
        * 悬浮窗不可触摸，不接受任何事件,同时不影响后面的事件响应。 
        wmParams.flags=LayoutParams.FLAG_NOT_TOUCH_MODAL  
                              | LayoutParams.FLAG_NOT_FOCUSABLE 
                              | LayoutParams.FLAG_NOT_TOUCHABLE; 
       */  
	    /** 
         *这里的flags也很关键 
         *代码实际是wmParams.flags |= FLAG_NOT_FOCUSABLE; 
         *40的由来是wmParams的默认属性（32）+ FLAG_NOT_FOCUSABLE（8） 
         */  
        //wmParams.flags=40;  
        wmParams.width=40;  
        wmParams.height=40;  
        wm.addView(bb, wmParams);//创建View  
    }  
}  
 

另外别忘了在AndroidManifest.xml文件中加入如下权限： 
<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" /> 

关于代码中wmParams.type的值的问题，下面给出一些数值参考：

/** 
         * Window type: the status bar.  There can be only one status bar 
         * window; it is placed at the top of the screen, and all other 
         * windows are shifted down so they are below it. 
         */ 
        public static final int TYPE_STATUS_BAR         = FIRST_SYSTEM_WINDOW; 
    
        /** 
         * Window type: the search bar.  There can be only one search bar 
         * window; it is placed at the top of the screen. 
         */ 
        public static final int TYPE_SEARCH_BAR         = FIRST_SYSTEM_WINDOW+1; 
    
        /** 
         * Window type: phone.  These are non-application windows providing 
         * user interaction with the phone (in particular incoming calls). 
         * These windows are normally placed above all applications, but behind 
         * the status bar. 
         */ 
        public static final int TYPE_PHONE              = FIRST_SYSTEM_WINDOW+2; 
    
        /** 
         * Window type: system window, such as low power alert. These windows 
         * are always on top of application windows. 
         */ 
        public static final int TYPE_SYSTEM_ALERT       = FIRST_SYSTEM_WINDOW+3; 

这个FIRST_SYSTEM_WINDOW的值就是2000。2003和2002的区别就在于2003类型的View比2002类型的还要top，能显示在系统下拉状态栏之上！ 


   可以看出来，2002的值的含义其实就是2000+2。数值2000的含义就是系统级窗口，2002和2003的区别就是 2003 比 2002还要更上一层！比如，type为2003的view，能显示在手机下拉状态栏之上！ 
   而关于flags等其他的属性请参考SDK文档
   
   
   下面给出实现可以移动的悬浮窗步骤：
   1、通过覆写悬浮View中onTouchEvent方法实现自由移动悬浮窗口。 


2、悬浮窗口坐标的移动实际是windowMananager.LayoutParams中x和y的变换，但是要注意设置相应的gravity。 


3、用windowManager创建的View，当不需要时，务必记住使用windowManager的removeView方法来移除，请在Activity相关生命周期中自行添加扫尾工作。

public class MyFloatView extends ImageView {
	private float mTouchStartX;
    private float mTouchStartY;
    private float x;
    private float y;
    
    private WindowManager wm=(WindowManager)getContext().getApplicationContext().getSystemService("window");
    private WindowManager.LayoutParams wmParams = ((MyApplication)getContext().getApplicationContext()).getMywmParams();

	public MyFloatView(Context context) {
		super(context);		
		// TODO Auto-generated constructor stub
	}
	
	 @Override
	 public boolean onTouchEvent(MotionEvent event) {
		 
		 
		 //获取相对屏幕的坐标，即以屏幕左上角为原点		 
	     x = event.getRawX();   
	     y = event.getRawY()-25;   //25是系统状态栏的高度
	     Log.i("currP", "currX"+x+"====currY"+y);
	     switch (event.getAction()) {
	        case MotionEvent.ACTION_DOWN:
	        	//获取相对View的坐标，即以此View左上角为原点
	        	mTouchStartX =  event.getX();  
                mTouchStartY =  event.getY();
                
	            Log.i("startP", "startX"+mTouchStartX+"====startY"+mTouchStartY);
	            
	            break;
	        case MotionEvent.ACTION_MOVE:	            
	            updateViewPosition();
	            break;

	        case MotionEvent.ACTION_UP:
	        	updateViewPosition();
	        	mTouchStartX=mTouchStartY=0;
	        	break;
	        }
	        return true;
		}
	 
	 private void updateViewPosition(){
		//更新浮动窗口位置参数
		wmParams.x=(int)( x-mTouchStartX);
		wmParams.y=(int) (y-mTouchStartY);
	    wm.updateViewLayout(this, wmParams);
	    
	 }

}