On OSX with Touch emulation enabled and iOS, Touch events are coming through with bogus delta values. The raw input coordinates are correct, but code in Finger.OnTouchRecorded mucks with the delta value in a way that I don't understand. It seems to assume that Touchscreen is sending a full accumulated delta, but that doesn't seem to be the case.

Here's a log of the values at various steps along the way (on OSX). "Raw Input" is the result of the raw IOCTL for the mouse. "SIM MOVED" is the touch simulation about to record a touch moved. "Finger" is logging in the Finger code just before the delta is mucked with. and "onFingerMoved" is what an onFingerMoved event sees.

I am moving the mouse 100% horizontally, in the positive direction (can see that from the raw values). But there are multiple negative deltas being reported incorrectly, and lots of zero deltas.

If I comment out the "touchState->delta -= previousTouchState->delta;" line, everything works correctly on both iOS and OSX.

Raw Input 1296 440
SIM MOVED: 0 old: (1295.00, 440.00) new: (1296.00, 440.00) delta: (1.00, 0.00)
Finger (prevrecord 7): accumDelta: (1.00, 0.00) prevDelta: (0.00, 0.00) curDelta: (1.00, 0.00) result: (1.00, 0.00)
onFingerMove: 1 -- delta (1.00, 0.00) (0.01, 0.00)

Raw Input 1297 440
SIM MOVED: 0 old: (1296.00, 440.00) new: (1297.00, 440.00) delta: (1.00, 0.00)
Finger (prevrecord 8): accumDelta: (1.00, 0.00) prevDelta: (1.00, 0.00) curDelta: (1.00, 0.00) result: (0.00, 0.00)
onFingerMove: 1 -- delta (0.00, 0.00) (0.00, 0.00)
^^^ wrong delta -- should be +1

Raw Input 1299 440
SIM MOVED: 0 old: (1297.00, 440.00) new: (1299.00, 440.00) delta: (2.00, 0.00)
Finger (prevrecord 9): accumDelta: (2.00, 0.00) prevDelta: (0.00, 0.00) curDelta: (2.00, 0.00) result: (2.00, 0.00)
onFingerMove: 1 -- delta (2.00, 0.00) (0.01, 0.00)

Raw Input 1300 440
SIM MOVED: 0 old: (1299.00, 440.00) new: (1300.00, 440.00) delta: (1.00, 0.00)
Finger (prevrecord 10): accumDelta: (1.00, 0.00) prevDelta: (2.00, 0.00) curDelta: (1.00, 0.00) result: (-1.00, 0.00)
onFingerMove: 1 -- delta (-1.00, 0.00) (-0.01, 0.00)
>>>>> ^^^^ wrong -1 delta

Raw Input 1301 440
SIM MOVED: 0 old: (1300.00, 440.00) new: (1301.00, 440.00) delta: (1.00, 0.00)
Finger (prevrecord 11): accumDelta: (1.00, 0.00) prevDelta: (-1.00, 0.00) curDelta: (1.00, 0.00) result: (2.00, 0.00)
onFingerMove: 1 -- delta (2.00, 0.00) (0.01, 0.00)
^^^^ wrong delta, should be +1

Raw Input 1302 440
SIM MOVED: 0 old: (1301.00, 440.00) new: (1302.00, 440.00) delta: (1.00, 0.00)
Finger (prevrecord 12): accumDelta: (1.00, 0.00) prevDelta: (2.00, 0.00) curDelta: (1.00, 0.00) result: (-1.00, 0.00)
onFingerMove: 1 -- delta (-1.00, 0.00) (-0.01, 0.00)
>>>>> ^^^^ wrong -1 delta

Raw Input 1303 440
SIM MOVED: 0 old: (1302.00, 440.00) new: (1303.00, 440.00) delta: (1.00, 0.00)
Finger (prevrecord 13): accumDelta: (1.00, 0.00) prevDelta: (-1.00, 0.00) curDelta: (1.00, 0.00) result: (2.00, 0.00)
onFingerMove: 1 -- delta (2.00, 0.00) (0.01, 0.00)
^^^^ wrong delta, should be +1

Raw Input 1304 440
SIM MOVED: 0 old: (1303.00, 440.00) new: (1304.00, 440.00) delta: (1.00, 0.00)
Finger (prevrecord 14): accumDelta: (1.00, 0.00) prevDelta: (2.00, 0.00) curDelta: (1.00, 0.00) result: (-1.00, 0.00)
onFingerMove: 1 -- delta (-1.00, 0.00) (-0.01, 0.00)
>>>>> ^^^^ wrong -1 delta