Overlay Guard

Overlay Guard is a high-performance system utility designed to bring the advanced privacy features of the 2026 Galaxy S26 Ultra to Android 13+ devices. By leveraging real-time sensor fusion and the WindowManager API, this app simulates a "software-defined" hardware privacy screen.

Project Info

Key	Value
Package	com.moclg.overlayguard
Target SDK	35 (Android 15)
Min SDK	33 (Android 13)
Language	Kotlin
Build System	Gradle 9.3.1 / AGP 8.7.3, Kotlin DSL
UI	Jetpack Compose (Material 3)
Target Device	Rooted Samsung Note 20 Ultra (custom kernel)

Technical Architecture

PrivacyOverlayService (AccessibilityService)

• Uses WindowManager.LayoutParams.TYPE_ACCESSIBILITY_OVERLAY to draw a black View over the status bar.
• Flags: FLAG_NOT_FOCUSABLE | FLAG_NOT_TOUCHABLE | FLAG_LAYOUT_IN_SCREEN — the overlay covers the notch/status bar without intercepting touch events.
• LAYOUT_IN_DISPLAY_CUTOUT_MODE_ALWAYS to cover display cutouts/notches.
• Sets PRIVATE_FLAG_IS_SCREEN_DECOR via reflection for elevated z-order on supported devices.
• Overlay height (default 150 px) and roll threshold are stored in SharedPreferences and updated at runtime.
• Supports pause / resume — toggling off stops the sensor and overlay without unregistering the accessibility service, so no re-enablement is needed.

Notification Suppression

• DND toggle — enables Do Not Disturb (ALARMS-only) via NotificationManager API when the overlay is active; restores on deactivation.
• Root DND fallback — also sets heads_up_notifications_enabled, zen_mode, and cmd notification set_dnd via root.
• Heads-up swipe dismissal — Samsung One UI renders heads-up notification (HUN) windows above TYPE_ACCESSIBILITY_OVERLAY. On TYPE_NOTIFICATION_STATE_CHANGED events while the overlay is active:
  • With root: PersistentRootShell executes input swipe for zero-latency physical dismissal.
  • Without root: AccessibilityService.dispatchGesture() simulates the same upward swipe.
• DND access is auto-granted via root on launch (cmd notification allow_dnd).

Sensor Fusion (RollSensorListener)

• Registers Sensor.TYPE_ROTATION_VECTOR at SENSOR_DELAY_UI.
• Derives a 3×3 rotation matrix via SensorManager.getRotationMatrixFromVector.
• Extracts orientation angles via SensorManager.getOrientation; index 2 = roll (radians → degrees).
• Trigger logic: |roll| > threshold ⟹ α = 1.0; otherwise α = 0.0.

Compose Dashboard (MainActivity)

• Start / Stop Toggle — on rooted devices, automatically runs settings put commands via su; on non-rooted devices:
  • If service is already enabled, pauses/resumes without opening settings.
  • Only opens ACTION_ACCESSIBILITY_SETTINGS when the service needs initial enablement.
• Height Slider — adjusts overlay height from 50 px to 500 px.
• Sensitivity Slider — adjusts roll threshold from 10° to 45°.
• Status card — shows green "Running without root" when active, or yellow "Root not detected" with setup instructions when inactive.

Root Automation (RootHelper / PersistentRootShell)

• Detects root by checking for su binary paths (Magisk, KernelSU, legacy).
• RootHelper executes commands via interactive su stdin (ProcessBuilder) — more compatible with Magisk/KernelSU than Runtime.exec(arrayOf("su", "-c", ...)).
• PersistentRootShell keeps a single su process alive for the service lifetime — commands are written to stdin with zero process-spawn overhead.

Restricted Settings Bypass (Android 13 / 14)

Starting with Android 13, sideloaded apps are blocked from enabling accessibility services. To bypass:

1. Go to Settings → Apps → Overlay Guard → ⋮ (three-dot menu).
2. Tap "Allow Restricted Settings".
3. Authenticate with your PIN / biometric.
4. Now navigate to Settings → Accessibility → Overlay Guard and enable the service.

On rooted devices this step is unnecessary — the root toggle writes the settings directly.

Building

# Requires JDK 17 — gradle.properties pins org.gradle.java.home
./gradlew clean assembleDebug
# Install on device
adb install -r app/build/outputs/apk/debug/app-debug.apk

Or download and install an apk file from release section.

Git Conventions

All commits must be signed off:

git commit -s -m "type: description"

Types: feat, fix, docs, refactor, chore.

License

Proprietary — all rights reserved.