LightMarkdownReader

A lightweight, fast, and modern markdown reader for Android. LightMarkdownReader provides a clean interface for reading markdown files on your Android device, with support for persistent file access and recent file tracking.

Features

• Markdown Rendering: Rich markdown rendering using Markwon library
• Recent Files: Automatic tracking of recently opened files with validation and cleanup
• Persistent Permissions: Maintains access to files across app restarts
• File Sharing: Share markdown files directly from the app
• Error Handling: Comprehensive error handling with user-friendly error messages
• Material Design 3: Modern UI following Material Design 3 guidelines
• Edge-to-Edge Display: Immersive full-screen experience

Architecture

LightMarkdownReader follows the MVVM (Model-View-ViewModel) architecture pattern with a clean separation of concerns:

Architecture Layers

┌─────────────────────────────────────────────────┐
│                 UI Layer                         │
│  - ReaderScreen (Jetpack Compose)               │
│  - MarkdownRenderer                              │
│  - TopBar & Components                           │
└─────────────────┬───────────────────────────────┘
                  │
┌─────────────────▼───────────────────────────────┐
│              ViewModel Layer                     │
│  - ReaderViewModel                               │
│  - UI State Management (StateFlow)               │
│  - Recent Files State                            │
└─────────────────┬───────────────────────────────┘
                  │
┌─────────────────▼───────────────────────────────┐
│               Data Layer                         │
│  - FileRepository (File I/O)                    │
│  - RecentFilesRepository (Persistence)          │
│  - Data Models (MarkdownFile, RecentFile)       │
└─────────────────────────────────────────────────┘

Key Components

UI Layer (ui/)

• ReaderScreen: Main composable screen that orchestrates the UI
• MarkdownRenderer: Handles rendering markdown content using Markwon
• TopBar: Navigation and action bar component
• Theme: Material Design 3 theming (Color, Type, Theme)

ViewModel Layer (viewmodel/)

• ReaderViewModel: Manages UI state and business logic
  • Handles file loading with proper error states
  • Manages recent files list
  • Exposes StateFlow for reactive UI updates

Data Layer (data/)

• FileRepository: Handles file system operations
  • Reads markdown files using Android ContentResolver
  • Validates file size (10MB limit)
  • Provides file metadata (name, size)
• RecentFilesRepository: Manages recent files persistence
  • Stores recent files using SharedPreferences
  • Validates file accessibility
  • Handles migration from legacy formats
• Models: Data classes for MarkdownFile and RecentFile

Utils (util/)

• TimeFormatter: Formats timestamps for recent files display

State Management

The app uses Kotlin StateFlow for reactive state management:

• ReaderUiState: Represents the current state (Empty, Loading, Success, Error)
• recentFiles: Flow of recent files list

File Access

Uses Android's Storage Access Framework (SAF) for secure file access:

• Persistent URI permissions for ongoing access
• Content resolver for reading files
• Handles permission revocation gracefully

Tech Stack

• Language: Kotlin
• UI Framework: Jetpack Compose
• Minimum SDK: 26 (Android 8.0)
• Target SDK: 36
• Architecture: MVVM
• Dependency Injection: Manual DI (lightweight)
• Markdown Library: Markwon
• Persistence: SharedPreferences (JSON via Gson)
• Testing: JUnit, MockK, Turbine, Coroutines Test

Project Structure

app/src/main/java/com/harrisonog/lightmarkdownreader/
├── MainActivity.kt              # App entry point
├── ui/
│   ├── screens/
│   │   └── ReaderScreen.kt     # Main screen composable
│   ├── components/
│   │   ├── MarkdownRenderer.kt # Markdown rendering
│   │   └── TopBar.kt           # Top app bar
│   └── theme/                  # Material Design theme
├── viewmodel/
│   └── ReaderViewModel.kt      # Main view model
├── data/
│   ├── FileRepository.kt       # File operations
│   ├── RecentFilesRepository.kt# Recent files management
│   ├── MarkdownFile.kt         # Data model
│   └── RecentFile.kt           # Recent file model
└── util/
    └── TimeFormatter.kt        # Time formatting utilities

Building

./gradlew assembleDebug

Testing

./gradlew test