How can I show Html/pdf on page(Using Canvas) and add images and text by dragging and dropping them and save Canvas as html ? I have tried jQuery UI for drag and drop images and text but it's not up to mark. Can I load html into canvas and perform the drag and drop on canvas?
No, you can't load actual html into canvas itself (largely for security reasons).
This canvas library does a fairly good job of "faking it":
http://html2canvas.hertzen.com/
But with a little learning, you may find that canvas itself has all the formatting/drawing capabilities you need.
And you can tie into window events (mouse, touch, requestAnimationFrame, etc) to get more: