创建由服务运行的系统覆盖以创建消息或图标

Question

我想创建一个由服务运行的系统覆盖，以拾取鼠标移动。但我无法拾取触摸/鼠标点。有人可以告诉我这段代码有什么问题。

我可以使用相同的代码从活动中获取鼠标移动，但不能从具有系统覆盖的服务中获取鼠标移动。

使用以下代码从MainActivity运行HUD：

    private OnClickListener btnHUDListener = new OnClickListener() {
    public void onClick(View v){
        startService(new Intent(MainActivity.this, HUD.class)); 
    }
};

以下是服务类：

    package com.btc.service;

import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.PixelFormat;
import android.os.IBinder;
import android.util.Log;
import android.view.Gravity;
import android.view.MotionEvent;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.widget.Toast;


public class HUD extends Service {
    HUDView mView;

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        Toast.makeText(getBaseContext(),"onCreate", Toast.LENGTH_LONG).show();


        mView = new HUDView(this);
        WindowManager.LayoutParams params = new WindowManager.LayoutParams(
                WindowManager.LayoutParams.TYPE_SYSTEM_OVERLAY,
                WindowManager.LayoutParams.FLAG_WATCH_OUTSIDE_TOUCH,
                PixelFormat.TRANSLUCENT);
        params.gravity = Gravity.RIGHT | Gravity.TOP;
        params.setTitle("Load Average");
        WindowManager wm = (WindowManager) getSystemService(WINDOW_SERVICE);
        wm.addView(mView, params);

    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        Toast.makeText(getBaseContext(),"onDestroy", Toast.LENGTH_LONG).show();
        if(mView != null)
        {
            ((WindowManager) getSystemService(WINDOW_SERVICE)).removeView(mView);
            mView = null;
        }
    }
}

class HUDView extends ViewGroup {
    private Paint mLoadPaint;

    public HUDView(Context context) {
        super(context);
        Toast.makeText(getContext(),"HUDView", Toast.LENGTH_LONG).show();

        mLoadPaint = new Paint();
        mLoadPaint.setAntiAlias(true);
        mLoadPaint.setTextSize(10);
        mLoadPaint.setARGB(255, 255, 0, 0);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawText("Hello World", 5, 15, mLoadPaint);
    }

    @Override
    protected void onLayout(boolean arg0, int arg1, int arg2, int arg3, int arg4) {


    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        //return super.onTouchEvent(event);
        Toast.makeText(getContext(),"onTouchEvent", Toast.LENGTH_LONG).show();
        int action = event.getAction();
        MyService.currentXPosition = event.getX();
        MyService.currentYPosition = event.getY();

        Log.v("A MotionEvent", "Action = " + action);
        Log.v("A MotionEvent", "X = " + MyService.currentXPosition + "Y = " + MyService.currentYPosition);

        if (action == MotionEvent.ACTION_MOVE) {
             // do something
        }

        if (action == MotionEvent.ACTION_UP) {
             // do something
        }

        //Toast.makeText(null,"onTouchEvent", Toast.LENGTH_LONG).show();
        return true;
    }
}