[Bug 48252] Input is dropped while drawing perfectly-vertical lines if tablet is set to 'Relative' mode

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=48252

beknonam at yevme.com changed:

           What    |Removed                     |Added
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                 CC|                            |beknonam at yevme.com

--- Comment #7 from beknonam at yevme.com ---
Created attachment 70457
  --> https://bugs.winehq.org/attachment.cgi?id=70457
fix for negative orAltitude

The XEvents' axis_data array only updates values that have changed, and sets
its size according to the maximum index of the changed axis +1.

For instance; the pointer's X value corresponds to the indice [0], the Y [1],
the NormalPressure [2], and so on. 
If only the X value of the pointer changes then the reported size of the
axis_data will be 1, axis_data[0] will hold the new X value of the pointer, and
any indice after [0] will have stale data from the previous frame.

However if only the NormalPressure changes, then the reported size of the
axis_data will be 3 and axis_data[2] will report the new NormalPressure,
however the indices for the X and Y in the axis_data will be left unaltered as
that axis has reported no change. Previously, the struct was cleared before use
at each motion_event, button_event, and proximity_event, due to this whenever
there was a change in a higher axis, but the the lower axis, such as X or Y
were unchanged the pointer would erratically teleport to the top-left corner
(0,0).

To fix this bug I added moved the memsets to the
X11DRV_AttachEventQueueToTablet so that the struct would only be cleared once
after initalization and not after each event callback, allowing for the
previous positions to be retained when only the pressure, or Y-axis changes.

Furthermore I added simple checks to only update axis that were changed, so
that axis with an index greater than the reported axis_data size will not
modified. This fixes the the negative OrAltitude bug.

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