JAMViewer

Just A Markdown Viewer - A lightweight, native macOS application for viewing and monitoring Markdown files in real-time.

Overview

JAMViewer just reads and renders markdown files... nothing more, nothing less. It automatically monitors your files for changes and updates the view in real-time, making it perfect for previewing Markdown while you write.

Features

• Real-Time File Monitoring: Automatically updates when your Markdown file changes
• Command Line Support: Open files directly from Terminal (JAMViewer file.md)
• Drag & Drop: Drag Markdown files onto the app to view them
• Keyboard Shortcuts:
  • ⌘O - Open file
  • ⌘+ or ⌘= - Increase font size
  • ⌘- - Decrease font size
  • ⌘0 - Reset font size
• Beautiful Typography: Custom styled headings, code blocks, and blockquotes
• Code Highlighting: Monospace font (Menlo) with background highlighting for code blocks
• Dark Mode Support: Automatically adapts to light and dark mode
• Native macOS App: Built with SwiftUI for optimal performance

Requirements

• macOS 12.0+
• Xcode 14.0+ (for building from source)

Installation

Building from Source

1. Clone this repository
2. Open JAMViewer.xcodeproj in Xcode
3. Add MarkdownUI via Swift Package Manager:
   • File → Add Package Dependencies...
   • Enter: https://github.com/gonzalezreal/swift-markdown-ui
4. Build and run (⌘R)

Usage

Opening Files

There are multiple ways to open Markdown files:

1. File Menu: Launch the app and use ⌘O or File → Open File...
2. Command Line: open -a JAMViewer path/to/file.md
3. Drag & Drop: Drag a .md file onto the app icon or window
4. Default App: Set JAMViewer as the default app for .md files

Viewing Markdown

Once a file is open, JAMViewer will:

• Display the rendered Markdown with styled typography
• Automatically refresh when the file is saved or modified
• Maintain your preferred font size across sessions

Architecture

JAMViewer is built with a clean SwiftUI architecture:

• JAMViewerApp.swift: Main app entry point with file opening and command-line handling
• ContentView.swift: Main view displaying rendered Markdown
• MarkdownRenderer.swift: Custom Markdown rendering component with styled typography
• FileManagerModel.swift: Observable model managing file selection state
• FileMonitor.swift: File system monitoring using Grand Central Dispatch
• FontSizeKeyboardShortcuts.swift: Custom keyboard shortcut handling for font size
• EmptyStateView.swift: Placeholder views for various states (empty, loading, error)

Typography Scale

The app uses a proportional typography scale based on the adjustable base font size:

• Body Text: Base font size (default: 16pt)
• H1: 2.0× base size
• H2: 1.5× base size with underline
• H3: 1.17× base size
• Code: 0.9× base size in Menlo font

Visual Styling

• Code Blocks: Menlo font with background fill and rounded borders
• Headings: Bold/semibold weights with appropriate spacing
• Blockquotes: Blue left border accent with indentation

Supported Markdown Elements

• Headings (H1, H2, H3)
• Paragraphs with bold and italic text
• Code blocks with syntax highlighting background
• Inline code snippets
• Blockquotes
• Ordered and unordered lists
• Links
• Images
• Tables
• And more via MarkdownUI

Technology Stack

• SwiftUI: Modern declarative UI framework
• MarkdownUI: Powerful Markdown rendering library
• Grand Central Dispatch: Efficient file system monitoring
• AppKit: Native macOS integration

Contributing

Contributions are welcome! Feel free to:

• Report bugs or request features via Issues
• Submit pull requests with improvements
• Suggest enhancements to the viewer or styling

License

MIT LICENSE