title: How to center PopupWindow?
body: <p>I created an Activity in which i add a button that throws a popup when is clicked. Here is the code of showPopup() method:</p>
  
  <pre><code>    private void showPopup() {
      LayoutInflater inflater = (LayoutInflater) this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
  
      View layout = inflater.inflate(R.layout.popup_layout, (ViewGroup) findViewById(R.id.popup_element), false);
  
      final PopupWindow pwindo = new PopupWindow(layout, LayoutParams.WRAP_CONTENT, LayoutParams.MATCH_PARENT, true);
  
      Button btnAgree = (Button) layout.findViewById(R.id.ok);
      btnAgree.setOnClickListener(new View.OnClickListener() {
          public void onClick(View v) {
              pwindo.dismiss();
          }
      });
  
      pwindo.showAtLocation(layout, Gravity.CENTER, 0, 0);
      }
  }
  </code></pre>
  
  <p>I would center it both vertically and orizzontally. I tried several ways that i see here on SO but none worked. Why i always get the popup window at the top of the screen?</p>