右上方的对角线试图在UIView上绘制

I've got a tablet called a Slate that I can process x,y points from. I can pass these x,y points to my "drawShape" function, the equivalent of a touchesMoved function. I have a custom UIView class designed for this purpose with 4 main functions. The first three are touchesbegan/moved/ended and there is a drawRect.I've got a tablet called a Slate that I can pro