Convert HTML5 Canvas drawing to DXF

General information for the website: Iris diaphragm online design tool
Kind of development: Customization of existing website
Num. of web pages/modules: 1
Description of requirements/features: www.iris-calculator.com is an online iris diaphragm design tool.

Currently our 'export to DXF' feature only outputs minimal drawing information.

We would like the DXF file to include all the canvas drawing details displayed on the website, layered appropriately. This would include the blades both at minimum apertures, plus dimensions.

The free version can be seen here: http://www.iris-calculator.com/version_1-5b/index.php
Enter the values to produce the drawing.
Example
Enter the following values, leaving the rest blank/default:
B. Max. Aperture = 60mm
C. Min. Aperture = 10mm
D. No. of leaves = 8
Click 'CALCULATE'

An example DXF output is attached.

Specific technologies required: HTML5, Canvas
Extra notes: