Android 实现全局浮动弹窗

全局浮动小窗口，类似于微信的语音通话全局小窗口，还有一些手机的桌面的全局操作按钮等，算是比较常用，简单记录一下。

实现原理：在Application中，getSystemService(Context.WINDOW_SERVICE) 获取WindowManager，然后通过WindowManager添加View, 手势滑动时实时更新该window的LayoutParams的x | y 坐标。

核心代码：

Application中创建window:

public class App extends Application {
   
    private SmallWindowView mWindowView;
    private WindowManager mWindowManager;
    private WindowManager.LayoutParams mLayoutParams;
    public SmallWindowView getWindowView() {
   
        return mWindowView;
    }
    public WindowManager getWindowManager() {
   
        return mWindowManager;
    }
    public WindowManager.LayoutParams getLayoutParams() {
   
        return mLayoutParams;
    }

    @Override
    public void onCreate() {
   
        super.onCreate();
        initSmallViewLayout();
    }

    public void initSmallViewLayout() {
   
        mWindowView = (SmallWindowView) LayoutInflater.from(this).inflate(R.layout.small_window, null);
        mWindowManager = (WindowManager) getSystemService(Context.WINDOW_SERVICE);
        mLayoutParams = new WindowManager.LayoutParams(
                getResources().getDimensionPixelSize(R.dimen.small_window_size), // 120dp
                getResources().getDimensionPixelSize(R.dimen.small_window_size),
                WindowManager.LayoutParams.TYPE_SYSTEM_ALERT,
                WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
                PixelFormat.TRANSLUCENT);
        mLayoutParams.gravity = Gravity.NO_GRAVITY;
        mWindowView.setWm(mWindowManager);
        mWindowView.setWmParams(mLayoutParams);
    }

    public void showWindowView() {
   
        if (mWindowManager != null && mWindowView.getWindowId() == null) {
   
            mWindowManager.addView(mWindowView, mLayoutParams);
        }
    }

    public void dismissWindowView() {
   
        if (mWindowManager != null && mWindowView != null && mWindowView.getWindowId() != null) {
   
            mWindowManager.removeView(mWindowView);
        }
    }
} 

定义一个View组件，内部处理滑动改变窗口位置参数：

public class SmallWindowView extends LinearLayout {
   
    private final static String TAG = SmallWindowView.class.getSimpleName();
    private final int screenHeight;
    private final int screenWidth;
    private int statusHeight;
    private float mTouchStartX;
    private float mTouchStartY;

    private float mLastRawX;
    private float mLastRawY