Re: How should Touchscreen Input Drives behave (OpenEZX pcap_ts)

From: Florent Thiery
Date: Thu May 18 2006 - 07:15:29 EST

As of now, I return
X_ABS, Y_ABS and PRESSURE values between 0 and 1000 (each).

Are you kidding ??? Does the touchscreen support pressure sensitivity? Normally it wouldn't, you'd have only two values... Because sensitivity touchscreens really are rare... That's why wacom does use the pen to report pressure info on their tablets
1) where does touchscreen calibration happen? The EZX phones (like many
other devices, I believe) only contain resistive touchscreens that
appear pretty uncalibrated. I'm sure the factory-set calibration
data must be stored somewhere in flash, but it's definitely handled
in the proprietary EZX userland, since their old kernel driver
doesn't have any calibration related bits.
I would say touchscreen calibration = scaling (to resolution) + reference points
2) what about the 'button' event. In addition to the pressure (which is
about 300 for regular stylus use, > 400 if you press hard and > 600 if
you use yourfinger), some existing TS drivers return a button press.
Is it up to me to decide after which pressure level to consider the
button to be pressed / released?
I would say the best would be to watch pressure evolution.... If it springs from 0 to 400 in less than sotg like 200 ms, then you got the "button" event. Is it feasable?

I got a question: does stylus usage on original A780 show the pressure sensitivity?

Another one: you say you're workin on building X-e. Are you talking about kdrive?


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