tree 80894e570141392ad89859bda1d1f77301ff9f8a
parent 24c22cc07d117cb29cc0e85effd9ee3abdb68f9d
author Kenneth Albanowski <kenalba@google.com> 1745256674 -0700
committer Chromium LUCI CQ <chromium-scoped@luci-project-accounts.iam.gserviceaccount.com> 1745256674 -0700

ozone: Subtract min-x,y from reported touchscreen coordinates

Subtract the minimum x and y values in reports of finger and stylus
events on a touchscreen.

This follows the model of processing input limits as described at:
https://wayland.freedesktop.org/libinput/doc/latest/tablet-support.html#out-of-bounds-motion-events

The result is that using a stylus on display touchscreen with
non-zero minimum values should have correct mapping between the
physical point touched and the display.

GetTouchscreenSize() was already reporting a range of (max-min) for each
axis, so this does not affect scaling, only shifts the origin of input
with peripherals that had a non-zero minimum x/y limits.

This does not add clamping; negative coordinates are possible.  The
input device is permitted to report coordinates outside the min-max
bounds, and this was already possible on the maximum sides.

The TabletEventConverterEvdev class already was adjusting for this
offset on opaque tablets.

Bug: b/318412090
Test: Validated on ToT w/ Brya, no effect on XP-Pen Artist 12 Pro, Wacom One (DTC133W0A)
Test: Validated on ToT w/ Brya, no effect on internal USI stylus
Test: Validated on ToT w/ Brya, desired effect on Movink DTH135, laser pointer matches stylus tip location.
Change-Id: Icb2cf259101d1d468d8e5dcf0f22ea510ed25045
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5751284
Reviewed-by: Sean O'Brien <seobrien@chromium.org>
Commit-Queue: Kenneth Albanowski <kenalba@google.com>
Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1449497}