scryglass

A lightweight, blazing-fast image viewer built with iced 0.14.

Install

Prebuilt binaries are attached to each release, self-contained with no runtime dependencies. The quickest path is cargo-binstall:

cargo binstall scryglass

Or build from source (cargo install scryglass), see Build & Run below for the optional native features.

Every release ships two downloads per platform, both with all features (video playback on statically linked FFmpeg, AV1/AVIF, and HEIC/HEIF):

• An OS application: a Windows installer (-setup.exe), a Linux AppImage, or a macOS .dmg.
• A slim archive holding just the binary: a .zip on Windows, a .tar.gz on Linux and macOS. This is what cargo binstall fetches.

The macOS app is unsigned, so Gatekeeper blocks the first launch. Either right-click the app and pick Open (macOS 14 and earlier), or open System Settings > Privacy & Security and click Open Anyway (macOS 15 Sequoia removed the right-click path). If it still refuses, clear quarantine from a terminal:

xattr -dr com.apple.quarantine /Applications/scryglass.app

The .dmg is the cleanest macOS install (drag the app out before launching). The slim .tar.gz suits cargo binstall and scripting.

To make scryglass your default viewer on Windows, install it (the installer puts it at a stable path), then turn on file associations in its Settings and pick it under Settings > Apps > Default apps. This registers every supported image, video, and comic format for the current user, no admin needed.

Uninstall

How you remove scryglass depends on how it was installed:

• Windows installer: run Uninstall scryglass from the Start menu or Settings > Apps. It offers to also delete your settings and thumbnail cache. Choose No to keep them for a reinstall.
• macOS: drag scryglass.app to the Trash.
• Linux AppImage or a portable archive: delete the file or folder.

Apart from the Windows installer's prompt, removal leaves your data in the standard per-user locations, all safe to delete by hand:

Data	Windows	Linux	macOS
Settings (config.toml)	%APPDATA%\scryglass	~/.config/scryglass	~/Library/Application Support/scryglass
Thumbnail cache	%LOCALAPPDATA%\scryglass	~/.cache/scryglass	~/Library/Caches/scryglass

The thumbnail cache is the larger of the two and can also be cleared anytime from File → Settings.

Features

• Smooth navigation: every keypress moves immediately, blurred placeholders cover slow loads, and images render as pre-allocated GPU textures
• Built for slow storage: all I/O runs off-thread with cancellation, so stalled reads never freeze the UI
• Smart caching: background prefetch into a byte-budgeted LRU cache, plus persistent disk thumbnails with deleted-file purging, 90-day expiry, and a 512 MB cap
• Archives as folders: browse zip/cbz, tar, 7z/cb7, and rar/cbr directly, including the animations and videos inside
• Animation playback: GIF, APNG, and animated WebP at native frame rate with correct frame compositing
• Video player (video feature): in-process FFmpeg decode with audio-synced playback, seeking, volume, looping, and auto-hiding controls
• Flexible zoom: six zoom modes, scroll-wheel zoom toward the cursor, drag-to-pan, and a crisp-pixels mode for pixel art
• EXIF aware: orientation applied, embedded thumbnails for instant previews, and an info panel with camera metadata
• File management: recycle-bin delete and in-place rename, with an optional read-only mode
• Native sorting: files order exactly like your file manager, with date and size options
• Comfortable: dark and light themes, a virtualized filmstrip, position slider, context menu, persistent settings, and a full keyboard map (? shows it)

Supported Formats

Type	Formats
Images	PNG, JPEG, GIF, BMP, WebP, TIFF, ICO, JPEG XL, SVG
Animations	GIF, APNG, animated WebP
Camera RAW	embedded previews from CR2, CR3, NEF, ARW, DNG, ORF, RW2, RAF, PEF, SRW
HEIC/HEIF	heif feature
AVIF	video feature (decoded through FFmpeg)
Video	MP4, MKV, WebM, MOV, AVI, M4V including AV1 (video feature)
Archives	zip, cbz, tar, tar.gz, tgz, 7z, cb7, rar, cbr

Keyboard & Mouse

Input	Action
→ / D, ← / A	Next / previous image (hold to scroll)
Home / End	First / last image
Scroll wheel, + / −	Zoom (toward cursor / center)
Ctrl+0, double-click	Reset zoom
Ctrl+1	Zoom to 100%
Left-drag	Pan (when zoomed in)
F / F11	Fullscreen
I	Info panel
R / Shift+R	Rotate view
Delete, F2	Recycle / rename
Space, J / L, M, ↑ / ↓	Video: play/pause, seek, mute, volume
?	Shortcut help
Right-click	Context menu
Esc	Close dialogs / leave fullscreen / dismiss menus

Build & Run

Requires a current stable Rust toolchain with Rust 2024 edition support. The default feature set is pure Rust except for the optional RAR support, which builds vendored unrar C++ sources.

cargo build                         # default image/archive viewer
cargo run -- <path>                 # open a file, folder, or archive
cargo build --no-default-features   # smallest dependency surface
cargo test                          # run tests

Advanced native builds (video, heif, and static FFmpeg/media linking) are covered in BUILD.md.

Configuration

Settings persist to config.toml in the platform config directory (%APPDATA%\scryglass on Windows, ~/.config/scryglass on Linux, ~/Library/Application Support/scryglass on macOS). Unknown keys are ignored, so configs survive upgrades in both directions. Most settings are editable in-app via File → Settings.

Architecture

scryglass follows the Elm Architecture (iced pattern):

• App: single source of truth for all state
• Message: enum driving all state transitions
• update(): handles messages, fires async tasks
• view(): pure rendering, no side effects

Images are loaded through iced's image::allocate() API, which returns GPU-resident Allocation objects. Holding an Allocation guarantees the texture renders immediately: no decode delay, no flicker. All I/O (directory scans, decodes, metadata, config writes) runs off the UI thread, and every load is cancellable the moment you navigate away.

License

MIT