Sir, I have a problem. I have created an application that will zommIn or zoomOut when the pushbutton is clicked. There are two api's for zoomin and zoomout. One is QwtPlotZoomer and QwtPlotMagnifier. But i am confused about which to use? And also I want to get some idea on how to zoomin or zoomout through pushbuttons. I had gone through the examples but all the examples have zoomin or zoomout through mouse or either by key.