Check if a canvas is empty

I have a form with a canvas place where users can sign in. Before send the form values to the server, I have to validate if some fields are fill out, among then, the canvas. How can I do that?

Which methods do you use to draw something on the canvas? After using one of those methods set a global variable to true to know later, that something has been drawn


Thank you for your quick reply. I will try and gives you a return.

Works perfectly!!
Thanks again!

This topic was automatically closed 7 days after the last reply. New replies are no longer allowed.