Is it possible to get values from chart drawed on HTML canvas?

Question

I can find number of ways how to draw chart on HTML5 canvas using javascript. For example drawing curves on coordinate system.

But is it possible to get values from that curve (for example when I know x- coordinate value, can I get y -coordinate value from any point on the curve?

Answer 1

No, the chart is just pixels painted on the canvas and nothing is "remembered".

If you know the definition of a curve you can find "y" given "x", but that's Math and you don't need an html canvas for that.