private void initPop() {

        View inflate = LayoutInflater.from(this).inflate(R.layout.pop_item, null);

        PopupWindow popupWindow = new PopupWindow(inflate, 400, 400);

        popupWindow.setBackgroundDrawable(new ColorDrawable ());

       popupWindow.setFocusable(true);

        popupWindow.setOutsideTouchable(true);

        setBackAphla(0.5f);

        popupWindow.showAtLocation(mButton1, Gravity.CENTER,ViewGroup.LayoutParams.WRAP_CONTENT,ViewGroup.LayoutParams.WRAP_CONTENT);

        popupWindow.setOnDismissListener(new PopupWindow.OnDismissListener() {

            @Override

            public void onDismiss() {

                setBackAphla(1f);

            }

        });

    }

    public void setBackAphla(float alpha){

        WindowManager.LayoutParams attributes = getWindow().getAttributes();

        attributes.alpha=alpha;

        getWindow().setAttributes(attributes);

    }