title: Angular2+ PDF Viewer to get co-ordinates of specific point
body: <p>guys, I am working on a digital signature application. Application is based on angular 5. I am viewing pdf by using <code>ng2-pdf-viewer</code>, now what I need to do is that a user needs to place a rectangle anywhere on the page loaded by <code>ng2-pdf-viewer</code>. So, when a user places the rectangle I need to get the exact coordinates of that location where the rectangle is placed so next time when I get the pdf opened again the user will see the rectangle on the same location. </p>
  
  <p>Is there any solution how can I achieve this? I will be really thankful if someone guides me a proper solution to achieve this.</p>
  
  <p>Thankyou</p>