view관련 작업한지 너무 오래되서 잘 기억나지는 않지만...
move 이벤트 도중에 자동으로 onDraw가 콜백 안되지 않나요?
move 이벤트 탐지로 인한 x, y값을 갱신 하셨으면, onDraw가 콜백될 수 있도록 invalidate 호출해 주어야 할듯 한데요.
Drawing
Drawing is handled by walking the tree and recording the drawing commands of any View that needs to update. After this, the drawing commands of the entire tree are issued to screen, clipped to the newly damaged area.
The tree is largely recorded and drawn in order, with parents drawn before (i.e., behind) their children, with siblings drawn in the order they appear in the tree. If you set a background drawable for a View, then the View will draw it before calling back to its onDraw() method. The child drawing order can be overridden with custom child drawing order in a ViewGroup, and with setZ(float) custom Z values} set on Views.
To force a view to draw, call invalidate().