问题
i am trying to make a drawing application.
i want to draw a single-touch motion path in android - like the way the Swype keyboard does it.
And consequently i want to store x-y coordinates of EACH of the pixels of the motion path into a data structure.
How can i use the MotionEvent pointers to do this?
回答1:
You probably don't have to store every pixel - just store a new one when certain parameters are met such as the pixel is further along or if the angle between one pixel and the next is greater than a certain threshold. From that you'll have a more compact poly line that will be easier to work with.
回答2:
You should look how to handle touch events here : http://developer.android.com/guide/topics/ui/ui-events.html
The example in the documentation of MotionEvent ( http://developer.android.com/reference/android/view/MotionEvent.html ) shows you how to get the coordinates of the touch event motion.
Then all you have to do is draw it (and maybe smooth it up a little)
来源：https://stackoverflow.com/questions/5202315/draw-a-single-touch-motion-path-in-android