PopupWindow高度MATCH_PARENT后 Android7.0以上showAsDropDown不能居于指定View下方

    @Override
    public void showAsDropDown(View anchor, int xoff, int yoff) {
        if(Build.VERSION.SDK_INT >= 24) {
            Rect rect = new Rect();
            anchor.getGlobalVisibleRect(rect);
            int h = anchor.getResources().getDisplayMetrics().heightPixels - rect.bottom;
            setHeight(h);
        }
        super.showAsDropDown(anchor, xoff, yoff);
    }