Noctua

An image viewer application for the COSMIC™ desktop

Features

• Multi-format support: Raster images (PNG, JPEG, WebP, etc.), SVG vector graphics, and PDF documents
• Navigation: Browse through folders with keyboard shortcuts
• Transformations: Rotate, flip, and crop images
• Zoom & Pan: Flexible viewing with zoom controls and panning
• Multi-page documents: Navigate PDF pages with thumbnail previews
• Metadata display: View EXIF data and file information
• Wallpaper setting: Set images as desktop wallpaper (multi-DE support)

Architecture

Noctua follows Clean Architecture principles with clear separation of concerns:

src/
├── main.rs              # Application entry point
├── ui/                  # UI Layer (COSMIC interface)
│   ├── app.rs           # Application state & lifecycle
│   ├── model.rs         # UI state + cached render data
│   ├── update.rs        # Message handlers
│   ├── sync.rs          # Model synchronization
│   ├── views/           # View components
│   └── components/      # Reusable widgets
├── application/         # Application Layer (use cases)
│   ├── document_manager.rs  # Document orchestration
│   ├── commands/        # Write operations (Transform, Crop)
│   └── services/        # Shared services (Cache)
├── domain/              # Domain Layer (business logic)
│   ├── document/        # Document abstractions & operations
│   │   ├── core/        # Traits & types (Renderable, Transformable)
│   │   ├── types/       # Implementations (Raster, Vector, Portable)
│   │   └── operations/  # Transform, render, export operations
│   └── errors.rs        # Domain errors
└── infrastructure/      # Infrastructure Layer (external systems)
    ├── loaders/         # Document loading (image, SVG, PDF)
    ├── cache/           # Thumbnail caching
    ├── filesystem/      # File operations
    └── system/          # System integration (wallpaper)

Key Patterns:

• MVU (Model-View-Update): Elm architecture via libcosmic
• Command Pattern: All operations go through commands
• Dependency Inversion: Domain has no dependencies on infrastructure
• Type-Erased Documents: DocumentContent enum for unified handling

Installation

A justfile is included by default for the [casey/just][just] command runner.

• just builds the application with the default just build-release recipe
• just run builds and runs the application
• just install installs the project into the system
• just vendor creates a vendored tarball
• just build-vendored compiles with vendored dependencies from that tarball
• just check runs clippy on the project to check for linter warnings
• just check-json can be used by IDEs that support LSP

Dependencies

Arch Linux

sudo pacman -S poppler-glib

Debian/Ubuntu

sudo apt install libpoppler-glib-dev

Fedora

sudo dnf install poppler-glib-devel

OpenSUSE

sudo zypper install poppler-glib-devel

Documentation

• Usage
• Features
• Development Guide

License

GPL-3.0-or-later