android 悬浮窗口的拖动

package net.xsmile.fv;
 
 
 import android.app.Application;
 import android.view.WindowManager;
 
 
 public class MyApplication extends Application {
     
     /**
      * 创建全局变量
      * 全局变量一般都比较倾向于创建一个单独的数据类文件，并使用static静态变量
      * 
      * 这里使用了在Application中添加数据的方法实现全局变量
      * 注意在AndroidManifest.xml中的Application节点添加android:name=".MyApplication"属性
      * 
      */
     private WindowManager.LayoutParams wmParams=new WindowManager.LayoutParams();
 
 
     public WindowManager.LayoutParams getMywmParams(){
         return wmParams;
     }
 }

package net.xsmile.fv;
 
 import android.content.Context;
 import android.util.Log;
 import android.view.MotionEvent;
 import android.view.WindowManager;
 import android.widget.ImageView;
 
 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");
     
     //此wmParams为获取的全局变量，用以保存悬浮窗口的属性
     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);
         
      }
 
 }

package net.xsmile.fv;
 
 import android.app.Activity;
 import android.graphics.PixelFormat;
 import android.os.Bundle;
 import android.view.Gravity;
 import android.view.WindowManager;
 import android.view.WindowManager.LayoutParams;
 
 public class MyFloatViewActivity extends Activity {
     /** Called when the activity is first created. */
     
     private WindowManager wm=null;
     private WindowManager.LayoutParams wmParams=null;
     
     private MyFloatView myFV=null;
 
     
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.main);
         //创建悬浮窗口
         createView();
     
     }
     
   
     
     private void createView(){
         myFV=new MyFloatView(getApplicationContext());
         myFV.setImageResource(R.drawable.icon);
         //获取WindowManager
         wm=(WindowManager)getApplicationContext().getSystemService("window");
         //设置LayoutParams(全局变量）相关参数
         wmParams = ((MyApplication)getApplication()).getMywmParams();
 
          /**
          *以下都是WindowManager.LayoutParams的相关属性
          * 具体用途可参考SDK文档
          */
         wmParams.type=LayoutParams.TYPE_PHONE;   //设置window type
         wmParams.format=PixelFormat.RGBA_8888;   //设置图片格式，效果为背景透明
 
         //设置Window flag
         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;
         */
         
         
         wmParams.gravity=Gravity.LEFT|Gravity.TOP;   //调整悬浮窗口至左上角
         //以屏幕左上角为原点，设置x、y初始值
         wmParams.x=0;
         wmParams.y=0;
         
         //设置悬浮窗口长宽数据
         wmParams.width=40;
         wmParams.height=40;
     
         //显示myFloatView图像
         wm.addView(myFV, wmParams);
         
     }
     
     @Override
     public void onDestroy(){
         super.onDestroy();
         //在程序退出(Activity销毁）时销毁悬浮窗口
         wm.removeView(myFV);
     }
     
    
     
 }

<?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
       package="net.xsmile.fv"
       android:versionCode="1"
       android:versionName="1.0">
     <application android:name=".MyApplication" android:icon="@drawable/icon" android:label="@string/app_name">
         <activity android:name=".MyFloatViewActivity"
                   android:label="@string/app_name">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
 
     </application>
     
     <uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />
 
 
 </manifest>