如何在特定位置显示自定义对话框？

我有一个按钮，单击它会弹出一个对话框。该对话框显示在中心。但我想将它显示在按钮下方。如何做到这一点？

我也尝试使用弹出窗口。这是代码

private void showPopup(final Activity context, Point p)
    {
        Display display = getWindowManager().getDefaultDisplay(); 
        width = display.getWidth();  // deprecated
        height = display.getHeight();  // deprecated

        int popupWidth =width;
        int popupHeight =height;

       // Inflate the popup_layout.xml
       LinearLayout viewGroup = (LinearLayout) context.findViewById(R.id.popup);
       LayoutInflater layoutInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
       View layout = layoutInflater.inflate(R.layout.datepicker_popup, viewGroup);

       // Creating the PopupWindow
       final PopupWindow popup = new PopupWindow(context);
       popup.setContentView(layout);
       popup.setWidth(popupWidth+p.x);
       popup.setHeight(popupHeight+p.y);
       popup.setFocusable(true);

       // Some offset to align the popup a bit to the right, and a bit down, relative to button's position.
       int OFFSET_X = 7;
       int OFFSET_Y = 65;

       // Clear the default translucent background
       popup.setBackgroundDrawable(new BitmapDrawable());

       // Displaying the popup at the specified location, + offsets.
       popup.showAtLocation(layout, Gravity.NO_GRAVITY, p.x + OFFSET_X, p.y + OFFSET_Y);



       // Getting a reference to Close button, and close the popup when clicked.
       Button close = (Button) layout.findViewById(R.id.close);
       close.setOnClickListener(new OnClickListener()
       {
           /* disable(content_view);*/
         @Override
         public void onClick(View v) 
         {
            popup.dismiss();
         }
       });

       }