WeatherSnap

An Android app that fetches live weather for a city, captures a photo with a custom CameraX camera, compresses it, and saves the report locally with notes. Built as a complete reference implementation of a modern, single-activity, Compose-first Android architecture.

Screens

Home	Search	Weather

Create Report	Saved Reports

Features

• City autocomplete — debounced search (300 ms) over Open-Meteo geocoding with an in-memory LRU cache.
• Live weather — temperature, condition, humidity, wind, pressure from Open-Meteo (no API key).
• Custom camera — full-screen CameraX preview + capture (no system intent), EXIF-correct rotation.
• Image compression — JPEG re-encoded at quality 80 with inSampleSize downsampling to ≤ 1080 px; "Original X KB → Compressed Y KB" displayed.
• Persistent reports — Room database, reactive list via Flow, image stored in filesDir/reports/.
• Survives rotation and process death — draft row is persisted to Room on first capture; SavedStateHandle holds the weather snapshot, draft id, and notes; Save is an idempotent UPDATE (no duplicate reports).

Tech stack

Kotlin · Jetpack Compose · Material 3 · MVVM · ViewModel · StateFlow · Coroutines · Hilt · Navigation Compose · Retrofit + Gson · OkHttp logging · Room · CameraX · Coil.

Architecture

app/
  data/
    image/        ImageCompressor (BitmapFactory + EXIF + JPEG)
    local/        Room entity, DAO, database, mappers
    remote/       Retrofit API, DTOs, mappers, WMO code mapping
    repository/   WeatherRepository, ReportRepository
  domain/model/   City, Weather, Report (pure Kotlin)
  di/             Hilt modules (Network, Database)
  navigation/     Routes, NavHost
  ui/
    weather/      search + current weather
    camera/       CameraX preview + capture
    report/       create/edit + draft persistence
    savedreports/ list of saved reports
    theme/        Material 3 dark theme

Single source of truth per screen: ViewModel exposes a StateFlow<UiState>, the composable collects it with collectAsStateWithLifecycle. Repositories return Result<T> for railway error handling.

Notable design decisions

• Two-flow search input — display text and API trigger are separate flows, so picking a suggestion doesn't re-run the search.
• Draft-backed Create Report — captured + compressed image is persisted as a STATUS_DRAFT row immediately. Save flips it to STATUS_SAVED via UPDATE. Process death between capture and save resumes the same row; double-save is a no-op.
• Weather snapshot in nav args — the Weather object is JSON-encoded into the route, lands in SavedStateHandle, and survives process death.
• EXIF rotation in compressor — BitmapFactory drops EXIF; we read TAG_ORIENTATION and apply a Matrix.postRotate before re-encoding so portrait captures stay portrait.

Setup

1. Open in Android Studio (Ladybug or newer) and let Gradle sync.
2. Run on a device or emulator with Android 7.0 (API 24)+.
3. Grant the camera permission on first capture.

No API key required.

API

Open-Meteo:

• Geocoding: https://geocoding-api.open-meteo.com/v1/search
• Forecast: https://api.open-meteo.com/v1/forecast