OnTouchListener
MotionEvent.ACTION_DOWN
ACTION_POINTER_DOWN
MOVE
POINTER_UP
UP
event.getSize()触摸尺寸
event.getPressure()触摸压力
OnTouchListener
MotionEvent.ACTION_DOWN
ACTION_POINTER_DOWN
MOVE
POINTER_UP
UP
event.getSize()触摸尺寸
event.getPressure()触摸压力