Yeah! I have implemented the functionality to have a live preview while a line is painted. Just a little playing with mouse events and it was done.
But as far as I was going through various examples and tutorials, I was seeing that so much has been done for trivial things. I got confused, leaving those behind for a while, just a hit of common sense I should say and it was done. No doubt, more efforts are required to proceed. Feeling charged!
Now I will be implementing the same for other entities.