fix: Correct inverted Android D-pad Up/Down (AXIS_HAT_Y double-inversion)

[GhagSagar23]

Summary

Fixes #123.

On Android, pressing the D-pad Up emitted GamepadButton.dpadDown (value 1.0), and Down emitted dpadUp. Root cause is a double inversion of the D-pad Y hat axis:

• gamepads_android's EventListener registers AXIS_HAT_Y with invert = true (EventListener.kt:27), so the value delivered to Dart is already flipped to up = +1.0 / down = −1.0 — the opposite of Android's native AXIS_HAT_Y (up = −1.0 / down = +1.0).
• AndroidMapping.normalizeDpadAxis still mapped per Android's native convention (value > 0 → dpadDown, value < 0 → dpadUp), so the two flips compounded.

AXIS_HAT_X is not inverted natively, so D-pad left/right were unaffected — matching the report.

Change

Corrected the sign comparison in a single canonical location — the AXIS_HAT_Y branch of AndroidMapping.normalizeDpadAxis — so dpadUp fires on value > 0 and dpadDown on value < 0, with a comment citing #123. EventListener.kt is intentionally left unchanged to avoid re-introducing a double-inversion.

• packages/gamepads/lib/src/mappings/android_mapping.dart
• packages/gamepads/test/mappings_test.dart — both-direction AXIS_HAT_Y regression

Fix-location decision (maintainer call welcome)

The reporter raised a genuine design choice for where to fix this:

1. Kotlin (EventListener.kt): drop the AXIS_HAT_Y inversion → raw/unnormalized values would then follow Android's 1.0 == down.
2. Dart (android_mapping.dart, this PR): keeps the library's existing 1.0 == up raw convention.

This PR takes option 2 to preserve the current raw-value convention (no breaking change) and because the mapping is pure Dart and directly unit-testable. Happy to switch to the Kotlin approach if you prefer — but the fix must live in exactly one place; applying it in both would double-invert and silently reintroduce the bug.

Tests

Added a both-direction regression to AndroidMapping > "normalizes hat d-pad axes":

• raw AXIS_HAT_Y = +1.0 (physical up) → dpadUp = 1.0, dpadDown = 0.0
• raw AXIS_HAT_Y = -1.0 (physical down) → dpadDown = 1.0, dpadUp = 0.0

This fails on the pre-fix code (which returned dpadDown = 1.0 for +1.0) and passes after the fix.

Note: the containerized Flutter runner was gated in this non-interactive session, so the fail→pass transition was verified by tracing, not executed. Please run before merge:

flutter pub get && flutter test packages/gamepads/test/mappings_test.dart
flutter analyze packages/gamepads

End-to-end hardware confirmation (physical Android device + controller, e.g. the reporter's SM-G781B + GameSir G8 Pro) is out of CI scope.

Deferred

• Analog stick Y-axis (leftStickY/rightStickY): the reporter separately observed up reading -1.0. Left untouched here — confirm it's a genuine inversion vs. Android's native joystick convention before changing; tracked as a follow-up reusing this PR's convention decision.
• CHANGELOG / version bump: not hand-edited — this melos workspace generates them at release time from the fix: PR title (CONTRIBUTING.md, "Creating a release").

Coordination

Thanks @fescrb for the precise root-cause analysis. You'd offered to submit this — glad to defer to you or just help with review; sharing this as a ready-to-go option while the fix-location question is settled.