CNA-VGAP-036: Android sensor conventions are unverified on hardware, and the default landscape remap is a reflection, not a rotation

CNA snapshot 009d40f5  ·  Known Issues › Verification gaps  ·  source links pinned to 009d40f5

No hardware QA record exists for Microsoft::Devices; CNA's own MOT2-001 analysis found the default-on landscape remap negates one axis (determinant -1), and the Android compass/motion sign conventions and demo copy are unverified or stale.

Identifier

CNA-VGAP-036

Category

Verification gap

Subsystem

Testing & evidence

Status

Open

Verified against

CNA 009d40f5 (009d40f5dd085c4e674d3479675fac84b12b3e0a)

Evidence basis

Source-verified: read at TARGET, not executed

Tests touching this area

Yes: see Current tests

Affected contract

Accelerometer, Gyroscope, Compass and Motion readings on Android; SetAndroidLandscapeRemapEnabled

Expected behaviour

Sensor axes and signs must match what WP7 games expect on real devices; a coordinate remap for a device rotation should itself be a rotation.

Actual behaviour at TARGET

AndroidSensorOrientation.hpp: ConvertAndroidPortraitToXnaLandscape returns {-x, y, z} or {x, -y, z}, and the remap is enabled by default although the same header concedes real WP7 “never” remaps (a deliberate CNA convenience deviation). AndroidMotionMath.hpp records the MOT2-001 finding that both cases are reflections that no quaternion can represent, left unresolved. devices-hardware-checklist.md states every test runs without sensor hardware; no filled-in copy of the QA template exists. The Android demo's DevicesDemo.cpp/.hpp differ from the desktop demo sources.

Source locations

• modules/devices/include/Microsoft/Devices/Sensors/Detail/AndroidSensorOrientation.hpp — ConvertAndroidPortraitToXnaLandscape; default-on remap
• modules/devices/include/Microsoft/Devices/Sensors/Detail/AndroidMotionMath.hpp — MOT2-001: the remap is a reflection
• docs/devices-hardware-checklist.md — no hardware in any test
• modules/devices/examples/demo_devices/src/DevicesDemo.cpp — desktop demo source that the Android copy no longer matches

Evidence

Checked by reading and diffing the two demo source trees at 009d40f5; not executed; no Android device was used.

Focused reproduction

No focused reproduction is known. Nothing has been invented here; the evidence above is what exists.

Current tests

Host tests (AndroidMotionMathTests.cpp, AndroidCompassMathTests.cpp) check the math, and synthetic-injection tests check dispatch.

Regression test

A recorded hardware run per sensor using docs/devices_sensor_hardware_qa_template.md, and a decision on the remap (a true rotation, or off by default).

Blast radius

Android games using tilt, rotation-rate or compass input; their axes and signs are unverified, and rate vectors transformed by a reflection change handedness.

Workaround

Call SetAndroidLandscapeRemapEnabled(false) and remap in the game, as WP7 games already do.