受益于:http://blog.youkuaiyun.com/guolin_blog/article/details/8689140 写的很好
一、首先需要两个权限:
1.<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" /> 这个是感知桌面的权限
2.<uses-permission android:name="android.permission.GET_TASKS"/> 获取桌面状态
二、然后需要来一个自定义控件:
做一个最简单的,一个红色的小球。
public class MyView extends LinearLayout{
WindowManager windowManager;
android.view.WindowManager.LayoutParams mParams;
int viewWidth;
int viewHeight;
public MyView(Context context) {
super(context);
windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
LayoutInflater.from(context).inflate(R.layout.activity_main, this);
View view = findViewById(R.id.small_window_layout);
viewWidth = view.getLayoutParams().width;
viewHeight = view.getLayoutParams().height;
}
public void setParams(android.view.WindowManager.LayoutParams smallWindowParams) {
this.mParams = smallWindowParams;
}
}
三、写一个MyWindowsManager,来创建和移除小球,这里是重点,在创建小球的时候,一下参数是必不可少的:
public static void creatView(Context context){
WindowManager windowManager = getWindowManager(context);
int screenWidth = windowManager.getDefaultDisplay().getWidth();
int screenHeight = windowManager.getDefaultDisplay().getHeight();
if (smallWindow == null) {
smallWindow = new MyView(context);
if (smallWindowParams == null) {
smallWindowParams = new LayoutParams();
smallWindowParams.type = LayoutParams.TYPE_PHONE;
smallWindowParams.format = PixelFormat.RGBA_8888;
smallWindowParams.flags = LayoutParams.FLAG_NOT_TOUCH_MODAL
| LayoutParams.FLAG_NOT_FOCUSABLE;
smallWindowParams.gravity = Gravity.LEFT | Gravity.TOP;
smallWindowParams.width = LayoutParams.WRAP_CONTENT;
smallWindowParams.height = LayoutParams.WRAP_CONTENT;
smallWindowParams.x = screenWidth;
smallWindowParams.y = screenHeight / 2;
}
smallWindow.setParams(smallWindowParams);
windowManager.addView(smallWindow, smallWindowParams);
}
}
四、启动一个服务,这个服务的作用是每隔0.5秒检查当前是否是桌面,由此来控制这个小球是否显示(是桌面显示,不是桌面隐藏)通过MyWindowsManager。