I expect to include a canvas on my page in which the user would write on it with finger or stylus (for a mobile app). I would like to detect whether the user has written on the canvas during a 24-hour period, and increment that digit each time it is used in another 24-hour period. The purpose is to show a nearby message that congratulates the user for persistent practice on that particular canvas. (That’s different from counting the number of times the page was accessed, for example.)
Is this possible? I have no idea of how to detect whether a canvas element has been drawn on or not.