The sample demonstrates some basic functions of a simple drawing app. You have the option to draw circles, boxes, triangles and lines. Originally I called it a Cad app cause you had the option edit the drawing and to export it to a dxf file.
I may add a couple more features in due time.
enjoy the sample page and feel free to pop a question. Btw it only works on webkit browsers due to mozilla html5 canvas incompatibilities
UPDATE: I updated my code to the latest version where I have solved the mozilla html5 canvas incompatibilities, so now it works, just fine, on both browsers.