metric of MotionEvent API getPressure, getSize

I'm working on a program which used the functions as title.

There's a problem that the tunctions above do not have their metrics on API website.

开发者_开发问答To avoid misunderstanding, here is an example about "metric" I metioned before.

Ex. size = pixel, pressure = kilogram(kg)

I have no idea about the metric at all.

Please show me where can I find the information I need.

Or, tell me under this topic.

thx again.

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getPressure(int) doc says:

Returns the current pressure of this event for the given pointer index (use getPointerId(int) to find the pointer identifier for this index). The pressure generally ranges from 0 (no pressure at all) to 1 (normal pressure), however values higher than 1 may be generated depending on the calibration of the input device.

So the pressure is measured in an abstract metric.

getSize(int) doc says:

Returns a scaled value of the approximate size for the given pointer index (use getPointerId(int) to find the pointer identifier for this index). This represents some approximation of the area of the screen being pressed; the actual value in pixels corresponding to the touch is normalized with the device specific range of values and scaled to a value between 0 and 1. The value of size can be used to determine fat touch events.

And the size seems also to be measured with an abstract metric.