My requirement is similar (not the same, of course) to the GuitarTuna app. I want to draw on an infinite vertical ScrollView as follows:
A trail emanating from the bottom of the pin on the top of the screen can be seen in the image above. It keeps scrolling with the ScrollView and disappears (by scrolling out of the screen) if the drawing is stopped.
What is the best way to create a similar kind of drawing interface?