Is there a way to compare drawing objects to letters?

I want to create learning letters app.

I'm allowing a user to draw on a canvas. After finish, I want to compare the drawing with one letter and show score for users or something like "Write It! Japanese" app.

I am using gesture to track the movements, and compare with letter stroke’s letter data.But i don't know comparing algorithms(i think it more accurate than OCR.)

Does anyone have any ideas on this?