Android中可自由移动悬浮窗口的实现

大家对悬浮窗概念不会陌生，相信每台电脑桌面的右上角都会有这么一个东西，它总是出现在所有页面的顶端（Top Show）。

但在Android 平台中如何实现这样的效果呢？先来看一看效果图。

看见在Google搜索框上面的那个Icon图片了嘛。

下面我就来详细介绍一下在Android平台下悬浮窗口的实现，并让它能够随手指的触摸而移动。

一、实现原理及移动思路调用WindowManager，并设置youtParams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youtParams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！然后通过覆写悬浮View中onTouchEvent方法来改变youtParams中x和y的值来实现自由移动悬浮窗口。

二、示例代码先来看一看悬浮View的代码，这里用一个ImageView作为演示[java]view plaincopyprint?1.public class MyFloatView extends ImageView {2.private float mTouchStartX;3.private float mTouchStartY;4.private float x;5.private float y;6.7.private WindowManager wm=(WindowManager)getContext().getApplicationContext().getSystemService("window");8.//此wmParams变量为获取的全局变量，用以保存悬浮窗口的属性9.private youtParams wmParams = ((MyApplication)getContext().getApplicationContext()).getMywmParams();10.11.public MyFloatView(Context context) {12.super(context);13.// TODO Auto-generated constructor stub14.}16.@Override17.public boolean onTouchEvent(MotionEvent event) {18.//获取相对屏幕的坐标，即以屏幕左上角为原点19.x = event.getRawX();20.y = event.getRawY()-25; //25是系统状态栏的高度21.Log.i("currP", "currX"+x+"====currY"+y);22.switch (event.getAction()) {23.case MotionEvent.ACTION_DOWN: //捕获手指触摸按下动作24.//获取相对View的坐标，即以此View左上角为原点25.mTouchStartX = event.getX();26.mTouchStartY = event.getY();27.Log.i("startP", "startX"+mTouchStartX+"====startY"+mTouchStartY);28.break;29.30.case MotionEvent.ACTION_MOVE: //捕获手指触摸移动动作31.updateViewPosition();32.break;33.34.case MotionEvent.ACTION_UP: //捕获手指触摸离开动作35.updateViewPosition();36.mTouchStartX=mTouchStartY=0;37.break;38.}39.return true;40.}41.42.private void updateViewPosition(){43.//更新浮动窗口位置参数44.wmParams.x=(int)( x-mTouchStartX);45.wmParams.y=(int) (y-mTouchStartY);46.wm.updateViewLayout(this, wmParams); //刷新显示47.}48.49.}上面的wmParams变量（即youtParams）的存储采用了extends Application的方式来创建全局变量，示例代码如下：[java]view plaincopyprint?1.public class MyApplication extends Application {2.3./**4.* 创建全局变量5.* 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7.* 这里使用了在Application中添加数据的方法实现全局变量8.* 注意在AndroidManifest.xml中的Application节点添加android:name=".MyApplication"属性9.*10.*/11.private youtParams wmParams=new youtParams();12.13.public youtParams getMywmParams(){14.return wmParams;15.}16.}再来看一看Activity中的代码：[java]view plaincopyprint?1.public class MyFloatViewActivity extends Activity {2./** Called when the activity is first created. */3.4.private WindowManager wm=null;5.private youtParams wmParams=null;6.7.private MyFloatView myFV=null;8.9.@Override10.public void onCreate(Bundle savedInstanceState) {11.super.onCreate(savedInstanceState);12.setContentView(yout.main);13.//创建悬浮窗口14.createView();15.16.}17.18.private void createView(){19.myFV=new MyFloatView(getApplicationContext());20.myFV.setImageResource(R.drawable.icon); //这里简单的用自带的Icom来做演示21.//获取WindowManager22.wm=(WindowManager)getApplicationContext().getSystemService("window");23.//设置LayoutParams(全局变量）相关参数24.wmParams = ((MyApplication)getApplication()).getMywmParams();25.26./**27.*以下都是youtParams的相关属性28.* 具体用途可参考SDK文档29.*/30.wmParams.type=LayoutParams.TYPE_PHONE; //设置window type31.wmParams.format=PixelFormat.RGBA_8888; //设置图片格式，效果为背景透明32.33.//设置Window flag34.wmParams.flags=LayoutParams.FLAG_NOT_TOUCH_MODAL35.| LayoutParams.FLAG_NOT_FOCUSABLE;36./*37.* 下面的flags属性的效果形同“锁定”。

38.* 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。

39.wmParams.flags=LayoutParams.FLAG_NOT_TOUCH_MODAL40.| LayoutParams.FLAG_NOT_FOCUSABLE41.| LayoutParams.FLAG_NOT_TOUCHABLE;42.*/43.44.wmParams.gravity=Gravity.LEFT|Gravity.TOP; //调整悬浮窗口至左上角，便于调整坐标45.//以屏幕左上角为原点，设置x、y初始值46.wmParams.x=0;47.wmParams.y=0;48.49.//设置悬浮窗口长宽数据50.wmParams.width=40;51.wmParams.height=40;52.53.//显示myFloatView图像54.wm.addView(myFV, wmParams);55.56.}57.58.@Override59.public void onDestroy(){60.super.onDestroy();61.//在程序退出(Activity销毁）时销毁悬浮窗口62.wm.removeView(myFV);63.}64.}最后，别忘了在AndroidManifest.xml中添加权限：[html]view plaincopyprint?1.<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW">2.</uses-permission>这样一个可以置顶显示、悬浮、且可自由移动的窗口就完工了。

运行一下，然后按Home键返回桌面试试看（不能点击返回键，演示程序这里设置了销毁窗体）三、一些说明WindowManager的方法很简单，基本用到的就三个addView，removeView，updateViewLayout。

而youtParams的属性就多了，非常丰富，这个也是关键所在。

这里例举两个window type：[java]view plaincopyprint?1./**2.* Window type: phone. These are non-application windows providing3.* user interaction with the phone (in particular incoming calls).4.* These windows are normally placed above all applications, but behind5.* the status bar.6.*/7.public static final int TYPE_PHONE = FIRST_SYSTEM_WINDOW+2;8.9./**10.* Window type: system window, such as low power alert. These windows11.* are always on top of application windows.12.*/13.public static final int TYPE_SYSTEM_ALERT = FIRST_SYSTEM_WINDOW+3;可以看出TYPE_SYSTEM_ALERT的显示层次比TYPE_PHONE还要高，有兴趣的可以试一试显示效果哦！另外关键的window flag：[java]view plaincopyprint?1./** Window flag: this window won't ever get focus. */2.public static final int FLAG_NOT_FOCUSABLE = 0x00000008;3.4./** Window flag: this window can never receive touch events. */5.public static final int FLAG_NOT_TOUCHABLE = 0x00000010;6.7./** Window flag: Even when this window is focusable (its8.* {@link #FLAG_NOT_FOCUSABLE is not set), allow any pointer events9.* outside of the window to be sent to the windows behind it. Otherwise10.* it will consume all pointer events itself, regardless of whether they11.* are inside of the window. */12.public static final int FLAG_NOT_TOUCH_MODAL = 0x00000020;最后，关于Android平台下的悬浮窗口，有人说很不友好，有人很困惑哪里会用到。