MetaPi – Android

MetaPi is an Android application built with Kotlin and Jetpack Compose that enables users to:

• Upload images from their device
• View and edit EXIF and IPTC metadata
• Crop and adjust photos
• Set or modify location data via Google Maps integration
• Prepare and upload images to cloud storage for use in Pi3D digital picture frames

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Table of Contents

1. Tech Stack
2. Architecture
3. Project Structure
4. Features
5. Setup & Installation
6. API Keys & Configuration
7. Build & Deployment
8. Planned Enhancements

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Tech Stack

• Language: Kotlin
• UI Framework: Jetpack Compose
• Architecture: MVVM (Model-View-ViewModel)
• EXIF Metadata Handling: Android ExifInterface
• IPTC Metadata Handling: Ashampoo/KIM (Java/Kotlin Image Metadata library)
• Maps Integration: Google Maps SDK for Android
• Maps Search Suggestions Places API
• Image Cropping: CanHub Image Cropper v4.6.0

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Architecture

The app follows the MVVM architecture to ensure separation of concerns:

• Model: Data classes and metadata parsing logic
• ViewModel: Holds UI state and business logic
• View (UI): Composable functions for screens and components

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Project Structure

app/
│
├── manifests/
│ └── AndroidManifest.xml
│
├── kotlin+java/com.technolab.metapi/
│ ├── data/ # Data classes (ImageItem), EXIF parsing (ExifInterface), IPTC parsing (Ashampoo/KIM)
│ ├── model/ # Domain models for metadata
│ ├── navigation/ # Navigation graph and routes
│ ├── ui/
│ │ ├── components/ # Reusable composable UI elements
│ │ ├── screens/ # Full screen UIs (Gallery, PhotoDetails, Crop, LocationPicker)
│ │ └── theme/ # Color, typography, shapes
│ ├── util/ # Helpers (file I/O, date formatting, permissions)
│ ├── viewmodel/ # ViewModels for managing screen state
│ ├── MainActivity.kt # Entry point
│ └── MetaPiApp.kt # Composable app root
│
├── res/ # Drawables, layouts, mipmaps, strings
└── build.gradle.kts # Module Gradle build file

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Features

• Gallery Screen – Displays images from local storage, selectable for editing
• Photo Details Screen – Displays full image + metadata, allows editing of EXIF/IPTC fields
• Crop Screen – Crops images via CanHub Image Cropper
• Location Picker – Allows location selection on a map, writes to metadata
• Google Maps Integration – Map preview and location tagging
• EXIF/IPTC Parsing – Reads and writes camera + descriptive metadata via ExifInterface and Ashampoo/KIM
• Cloud Upload Preparation – Processed images ready for Pi3D frame sync

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Setup & Installation

1. Clone the Repository

   git clone <repo-link>
   cd MetaPi-Android

2. Open in Android Studio

3. Sync Gradle

• Android Studio should prompt automatically.

4. Configure Google API Keys

• Enable Maps SDK for Android and Places API in Google Cloud Console.

• Add your API key in local.properties:

  MAPS_API_KEY=your_api_key_here

5. Run the App

• Select an emulator or physical device and click Run.

API Keys & Configuration

• Google Maps SDK for Android – Displays maps for location picking.
• Google Places API – Autocomplete and geocoding.

Security Note: Store API keys in local.properties or environment variables. Do not commit them to source control.

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Build and Deployment

1. Build > Generate Signed Bundle / APK
2. Choose APK → Provide keystore details → Release.
3. Output is in app/release/app-release.apk.

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Planned Enhancements

• Direct Pi3D Picture Frame integration via MQTT or cloud sync.
• Frame preview simulation.