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

[Andy Ross <andy@plausible.org>]

Harald Welte wrote:
> 0) What kind of X/Y/Pressure values should I return?  Are they supposed
>    to be scaled to the X/Y resolution of the LCD?  As of now, I return
>    X_ABS, Y_ABS and PRESSURE values between 0 and 1000 (each).
>
>    However, the coordinates are actually inverted, so '0,0' corresponds
>    to the lower right corner of the screen, whereas '1000,1000' is the
>    upper left corner.  Shall I invert them (i.e. return 1000-coord')?

The native driver reports pressure as either 65535 or 0, and doesn't
(seem to) scale the x/y values at all.  The uncalibrated values and
180 degree rotation (actually, my phone shows a slight rotation error
or a few pixels) are definitely reported to user space without
modification.

A matrix-based recalibrator will handle any orientation so long as the
corners are known, and so long as you report a pressure of zero
meaning "pen up" everything should be compatible regardless of the
units you choose.

Andy
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/