LightningView Image Viewer and Browser

A lightning-fast cross-platform image viewer written in Rust

This is a very slim image viewer that aims to replicate the most important functions found in commercial software like ACDSee.

Core Design goals

• Lightweight
• Cross Platform
• Common image format support
• RAW file support for popular cameras
• Basic FITS support with autostretching
• Video playback with audio and subtitles
• Browsing through the current directory with the keyboard (configurable)
• Pan/Zoom with the mouse
• Basic file operations such as deletion
• Quick way to start the default image editor (planned)

Non-goals

• Any form of image modification
• File format conversion
• Plugin system
• Complex histogram based stretching for FITS

Installation

Download the appropriate package from the release page

Arch Linux users can install by running yay -S lightningview or paru -S lightningview

Command Line Parameters

To start viewing images:

lightningview <imagefile.ext>

To open an image in windowed mode instead of fullscreen:

lightningview /windowed <imagefile.ext>

To print verbose debug logs to stdout (useful for diagnosing startup failures and HDR support — it reports the selected GPU backend and the display's HDR capability):

lightningview /debug <imagefile.ext>

On Windows this attaches to the launching terminal's console so the output is visible despite the GUI build having no console of its own. The flags can be combined and given in any order (e.g. lightningview /windowed /debug <file>).

To register as default program for viewing images on older versions of Windows:

lightningview.exe /register

To remove this registration from your windows registry and settings:

lightningview.exe /unregister

Controls

Input	Action
Page Up	Show previous image in directory
Page Down	Show next image in directory
Home	Jump to first image in directory
End	Jump to last image in directory
R	Sort images randomly
N	Sort images by name
F	Toggle fullscreen
Enter	Toggle between scale to fit and 1:1 display
Delete	Delete the currently viewed image file
Ctrl+C	Copy current image to clipboard
Mouse wheel	Zoom in / out
Drag Mouse	Pan image

Configuration

On first run LightningView writes a config file with the default settings, which you can edit afterwards:

• Linux / macOS: ~/.config/lightningview/config.toml
• Windows: %APPDATA%\lightningview\config.toml

The navigation keys are configurable. Each action is bound to a key pair, either "arrows" (Left / Right) or "pageupdown" (Page Up / Page Down):

[keybindings]
# Seek backward / forward within a playing video.
video_seek = "arrows"
# Move to the previous / next file in the directory.
file_browse = "pageupdown"

File browsing works whether an image or a video is shown. To restore the old behaviour where the arrow keys browse files, swap the two values.

Video playback

Video files are detected by their extension and handed to an ffmpeg-backed player that runs alongside the image viewer. Playback includes synchronized audio (the audio track drives the A/V clock; videos without audio fall back to a wall clock) and subtitle rendering. A seek/progress bar is shown transiently on screen when seeking or toggling playback.

By default the cursor keys seek within a playing video while Page Up / Page Down move to the previous / next file. File browsing works the same way whether an image or a video is shown. These bindings are configurable — see Configuration.

Video controls

Input	Action
Space	Toggle play / pause
Left Cursor	Seek backward 5 seconds
Right Cursor	Seek forward 5 seconds
Ctrl+Left Cursor	Seek backward 60 seconds
Ctrl+Right Cursor	Seek forward 60 seconds
Page Up	Show previous file in directory
Page Down	Show next file in directory
A	Cycle through audio tracks
S	Cycle through subtitle tracks
F	Toggle fullscreen

Supported image formats

General image formats:

• BMP
• GIF
• ICO
• JPEG
• JPEG-XL
• PNG
• PNM
• SVG
• TIFF
• TGA
• WEBP
• XBM
• XPM

RAW formats:

• Minolta MRW
• Sony ARW, SRF and SR2
• Mamiya MEF
• Olympus ORF
• Samsung SRW
• Epson ERF
• Kodak KDC
• Kodak DCS
• Panasonic / Leica RW2
• Fuji RAF
• Kodak DCR
• Adobe DNG
• Pentax PEF
• Canon CRW
• Leaf / Phase One IIQ
• Hasselblad 3FR
• Nikon NRW
• Nikon NEF
• Leaf MOS
• Canon CR2
• ARRI's ARI
• Astrophotography FITS (experimental)

Supported video formats

• MP4
• MKV
• WEBM
• AVI
• MOV
• M4V
• MPG / MPEG
• WMV
• FLV
• TS

(Decoding is handled by ffmpeg, so most common audio/video codecs within these containers are supported.)

TODO / Feature Requests

• Add a way to edit the currently viewed file
• Improved FITS handling
• Display sorting mode on screen when pressing R or N
• OpenCL support for RAW processing

Compiling

Just run the usual command:

cargo build --release

Under Linux, you may need to install additional dependencies first:

apt install libx11-dev libcairo-dev libxcursor-dev libxfixes-dev libxinerama-dev libxft-dev libpango1.0-dev libstdc++-11-dev

Video playback is built on ffmpeg, so the ffmpeg development libraries are also required:

apt install libavcodec-dev libavformat-dev libavutil-dev libswscale-dev libswresample-dev

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