title: How to draw point to a QGraphicsView at run time without clearing the previous drawn points?
body: <p>I am new to Qt, How to draw point to a QGraphicsView at run time without clearing the previous drawn points? I have implemented a simple app which draw points without using timer. I want to update this using timer. How to do this? Please help.</p>
  
  <pre><code>     QApplication a(argc, argv);
       QGraphicsScene scene(0,0,640,480);
       QGraphicsView view(&amp;scene);
       QPen pen(Qt::black);
       int x = 0;
       int y = 0;
  
       double rad = 1;
       while(y &lt; 640)
       {
          scene.addEllipse(x-rad, y-rad, rad*2.0, rad*2.0, QPen(), QBrush(Qt::SolidPattern));
          x++;
          y++;
       }
  
      view.show();
      return a.exec();
  </code></pre>