tranformAbsolute has a pretty simple job, that of running the X/Y
values from a device through the transformation matrix. The tricky bit
comes when the current device state doesn't include one of the
values. In that case, the last delivered value is back-converted to
device space and used instead.
The logic was twisted though, confusing GCC's uninitialized value
detection logic and emitting warnings.
This has been fixed by changing the code to:
1) Detect whether the ValuatorMask includes X/Y values
2) If either are missing, back-convert the current values into ox/oy
3) When X/Y are present, set ox/oy to the current value
4) Transform
5) Store X/Y values if changed or if they were set before.
Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
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