Files
ledgrab/server
alexei.dolgolyov ef1f9eade2 feat(android): production-readiness pass — security, perf, compat, UI/UX
Multi-axis lift to ship-quality after a full review:

Security
- ApiKeyManager: per-install random API key, persisted via SharedPreferences
  with synchronous first-write; threaded into uvicorn via the
  LEDGRAB_AUTH__API_KEYS env var; embedded in QR as a URL fragment (#k=)
  so it never appears in HTTP requests or server logs; frontend reads
  location.hash on first visit and strips it via history.replaceState
- Root.runAsRoot(argv: Array<String>) overload with POSIX shell-quoting to
  eliminate the shell-injection footgun (= excluded from unquoted-safe set)
- UsbSerialBridge: ContextCompat.RECEIVER_NOT_EXPORTED + intent.package
  check in the broadcast receiver for defence-in-depth across API levels
- Release builds refuse to silently fall back to debug keystore; require
  ANDROID_KEYSTORE_* env vars or explicit
  ANDROID_ALLOW_DEBUG_SIGNED_RELEASE=1
- Crash log retention capped at 10 entries
- Fatal-error stack trace hidden behind a toggle on the error screen

Performance
- ScreenCapture / RootScreenrecord reuse a single RGBA ByteArray per
  pipeline instead of allocating per frame — eliminates ~15 MB/s GC churn
  at 30 fps on low-end TV boxes
- Frame pacer switched from System.currentTimeMillis() + integer division
  (~30.3 fps drift) to SystemClock.elapsedRealtimeNanos with a catch-up
  accumulator
- ScreenCapture computes capture dimensions from source aspect ratio so
  non-16:9 displays don't get squashed
- RootScreenrecord input pump backs off 5 ms when MediaCodec is starved,
  ending a tight spin that burned a CPU core on decoder stalls
- QR cached by URL — onResume from background no longer rebuilds the
  560×560 bitmap each time
- ApiKey commit() pre-warmed off Main on app startup

Compatibility
- compileSdk / targetSdk bumped to 35 (Play Store requirement)
- armeabi-v7a build path added to build script + conditionally included
  in gradle splits when the matching wheel is present in android/wheels/
- Foreground service type declared as mediaProjection|specialUse with
  PROPERTY_SPECIAL_USE_FGS_SUBTYPE rationale; promotion via
  ServiceCompat.startForeground with the correct type per mode
- NetworkUtils picks Ethernet > Wi-Fi > VPN > cellular instead of just
  activeNetwork — fixes wrong-URL on TV boxes with both Ethernet + Wi-Fi
- enableOnBackInvokedCallback=true for Android 15 predictive-back
- Splash screen API via androidx.core:core-splashscreen — hides Chaquopy
  stdlib unpack delay on cold first launch

UI / UX
- All previously hardcoded English strings (root prompt, permission
  denial, fatal-error screen, notification text) now localised across
  en/ru/zh
- Monochrome notification icon (was a colored launcher → gray blob in
  status bar)
- 320×180 TV banner (was the square launcher → squashed on Leanback row)
- ViewStub-based running panel (deferred inflation)
- ObjectAnimator pulse on the Running status dot for liveness feedback
- "Starting…" button state while root is being probed
- Autostart checkbox hidden entirely on unrooted devices
- "No network" status when getLocalIpAddress returns null
- QR fallback hint text
- Animator cancelled in onStop to avoid leaking view hierarchy

Lifecycle hardening (from review)
- RootScreenrecord: processLock serialises EOF respawn vs concurrent
  stop() to prevent orphaned screenrecord processes
- CaptureService.restartRootPipeline: publish-before-start under
  @Synchronized to close the orphan window during watchdog restarts
- ScreenCapture.MediaProjection.Callback.onStop just flips
  running=false instead of calling stop() (which self-joined
  captureThread and hung 500 ms)
- updateUI early-returns when lateinit not initialised (fatal-error path)
- Watchdog give-up bound fixed (>= instead of >, was allowing 4 attempts)

server/android_entry.py accepts an optional api_key, sets
LEDGRAB_AUTH__API_KEYS={"android":<key>} as JSON before any LedGrab
import, logs a clear error if pydantic-settings parsing doesn't land
the value back in config (defensive guard against future settings
behaviour drift).

server/static/js/app.ts: bootstrap reads #k= from location.hash,
persists to localStorage, then strips via history.replaceState.

Two independent code-review passes; 147 relevant server tests still
pass; TypeScript and ruff clean.
2026-05-26 12:52:14 +03:00
..
2026-05-26 00:35:38 +03:00

LedGrab - Server

High-performance FastAPI server that captures screen content and controls WLED devices for ambient lighting.

Overview

The server component provides:

  • 🎯 Real-time Screen Capture - Multi-monitor support with configurable FPS
  • 🎨 Advanced Processing - Border pixel extraction with color correction
  • 🔧 Flexible Calibration - Map screen edges to any LED layout
  • 🌐 REST API - Complete control via 25+ REST endpoints
  • 💾 Persistent Storage - JSON-based device and configuration management
  • 📊 Metrics & Monitoring - Real-time FPS, status, and performance data

Quick Start

# Start server
docker-compose up -d

# View logs
docker-compose logs -f

# Stop server
docker-compose down

Server runs on: http://localhost:8080

Option 2: Python

# Create virtual environment
python -m venv venv

# Activate
source venv/bin/activate  # Linux/Mac
venv\Scripts\activate      # Windows

# Install dependencies
pip install .

# Set PYTHONPATH
export PYTHONPATH=$(pwd)/src  # Linux/Mac
set PYTHONPATH=%CD%\src       # Windows

# Run server
uvicorn ledgrab.main:app --host 0.0.0.0 --port 8080

Installation

Requirements

  • Python 3.11+ (for Python installation)
  • Docker & Docker Compose (for Docker installation)
  • WLED device on your network

See ../INSTALLATION.md for comprehensive installation guide.

Configuration

Configuration File

Edit config/default_config.yaml:

server:
  host: "0.0.0.0"
  port: 8080
  log_level: "INFO"

processing:
  default_fps: 30        # Target frames per second
  max_fps: 60           # Maximum allowed FPS
  border_width: 10      # Pixels to sample from edge

wled:
  timeout: 5            # Connection timeout (seconds)
  retry_attempts: 3     # Number of retries

storage:
  devices_file: "data/devices.json"

logging:
  format: "json"
  file: "logs/ledgrab.log"

Environment Variables

# Server configuration
export LEDGRAB_SERVER__HOST="0.0.0.0"
export LEDGRAB_SERVER__PORT=8080
export LEDGRAB_SERVER__LOG_LEVEL="INFO"

# Processing configuration
export LEDGRAB_PROCESSING__DEFAULT_FPS=30
export LEDGRAB_PROCESSING__BORDER_WIDTH=10

# WLED configuration
export WLED_WLED__TIMEOUT=5

Usage

WLED Device Setup

Important: Configure your WLED device using the official WLED web interface before connecting it to this controller:

  1. Access WLED Interface: Open http://[wled-ip] in your browser
  2. Configure Device Settings:
    • Set LED count and type
    • Configure brightness, color order, and power limits
    • Set up segments if needed
    • Configure effects and presets

This controller only sends pixel color data - it does not manage WLED settings like brightness, effects, or segments. All WLED device configuration should be done through the official WLED interface.

API Documentation

Quick Example

# 1. Add device
curl -X POST http://localhost:8080/api/v1/devices \
  -H "Content-Type: application/json" \
  -d '{"name":"Living Room","url":"http://192.168.1.100","led_count":150}'

# 2. Start processing
curl -X POST http://localhost:8080/api/v1/devices/{device_id}/start

# 3. Check status
curl http://localhost:8080/api/v1/devices/{device_id}/state

Testing

# Run all tests
pytest

# Run with coverage
pytest --cov=ledgrab --cov-report=html

# Run specific test
pytest tests/test_screen_capture.py -v

Development

Project Structure

src/ledgrab/
├── main.py              # FastAPI application
├── config.py            # Configuration
├── api/                 # API routes
├── core/                # Core functionality
│   ├── screen_capture.py
│   ├── wled_client.py
│   ├── calibration.py
│   └── processor_manager.py
├── storage/             # Data persistence
└── utils/               # Utilities

Code Quality

# Format code
black src/ tests/

# Lint code
ruff check src/ tests/

License

MIT - see ../LICENSE

Support