6.1 KiB
k-shrink
Wayland clipboard daemon that automatically compresses images the moment you copy them. Copy a 3 MB screenshot, paste a 300 KB WebP — no extra steps.
Quick Install (Arch Linux)
yay -S k-shrink
systemctl --user enable --now k-shrink.service
For other installation methods see INSTALL.md.
How It Works
k-shrink runs silently in the background. When it detects an image on the clipboard (from a browser, image viewer, or file manager), it compresses it with your configured format and quality and writes the result back. Your next paste delivers the smaller image.
A SHA-256 hash of the output bytes prevents k-shrink from reprocessing its own output, so there are no infinite loops.
Why?
Recently, I found myself sharing tons of memes and screenshots with friends, and it has come to my attention that many of those images are HUGE and it makes my blood boil. So, I decided to build a tool that will automatically take the image I have copied, whether from the web/facebook/discord/whatever or local files, or ftp, and shrink using user provided configuration (which format, quality, etc) and then put the shrunk image back to the clipboard, so that when I paste it, it's already shrunk and ready to be shared.
Configuration
Config file: ~/.config/k-shrink/config.toml (created with defaults if absent).
[general]
format = "webp" # output format
quality = 80 # 0-100, only for jpeg/avif
poll_ms = 500 # clipboard polling interval (ms, min 100)
extra_mimes = [] # additional MIME aliases (see below)
Config Reference
| Field | Type | Default | Description |
|---|---|---|---|
format |
string | "webp" |
Output image format. See formats table below. |
quality |
integer 0–100 | 80 |
Compression quality. Applied only for jpeg and avif. Ignored for all lossless formats. |
poll_ms |
integer ≥ 100 | 500 |
How often to poll the clipboard (ms). Lower = more responsive, more CPU. |
extra_mimes |
string array | [] |
Extra MIME types to serve alongside the real one. Same compressed bytes, different label. Useful when the paste target only requests a specific type. |
Supported Formats
| Format | Lossy | Notes |
|---|---|---|
webp |
No | Best for screenshots/UI. Smaller than PNG. Default. |
jpeg |
Yes | Best for photos. quality applies. |
avif |
Yes | Modern, better than JPEG. quality applies. |
png |
No | Universal lossless. No size reduction vs source PNG. |
qoi |
No | Fast lossless. Usually larger than PNG. |
farbfeld |
No | Simple 16-bit lossless. Rarely needed. |
tiff |
No | Lossless TIFF. Professional workflows. |
gif |
No | 256 colors only. Avoid for photos. |
hdr |
No | Radiance HDR floating-point. |
openexr |
No | OpenEXR high dynamic range. |
bmp |
No | Uncompressed. Will be larger than source. |
tga |
No | Uncompressed. |
pnm |
No | Uncompressed. |
ico |
No | Uncompressed. |
Troubleshooting
Paste fails in Discord / Slack / browser
Some apps only request image/png even if other formats are available.
Use extra_mimes to serve the compressed bytes under that label:
[general]
format = "webp"
extra_mimes = ["image/png"]
The image is still encoded as WebP; the label is just what k-shrink advertises. Most apps decode by content rather than MIME type, so this works.
Images keep getting reprocessed (loop)
k-shrink uses a SHA-256 hash of its output to skip reprocessing. If you see a loop,
check that IMAGE_MIMES priority is intact (webp is listed first so k-shrink's own
output is matched before external types). This should not occur in normal usage.
File-manager copies not detected
Filesystem copies (Ctrl+C in Nautilus, Dolphin, etc.) are detected via text/uri-list.
Only single-image files are supported. Multi-file selections and non-image files are
ignored silently.
Portability
Wayland only. The architecture isolates platform code in the platform crate, so
X11/Windows/macOS backends can be added without touching business logic.
Architecture
bin (k-shrink) → lib + platform + config
platform → lib + wl-clipboard-rs
config → lib + serde/toml/dirs
lib → image + sha2 (zero platform deps)
- lib — pure image compression logic, no platform deps, fully unit-tested.
- config — TOML parsing, validation, and path resolution.
- platform — Wayland clipboard backend via
wl-clipboard-rs. - bin — tokio event loop; orchestrates the other three crates.
Contributing
Contributions are welcome. Fork the repo and open a pull request. Please include tests for new behavior and follow the existing code style.
License
MIT. I seriously don't care what you do with this code or binaries, do whatever you want with it. If somehow it breaks something, it's your problem, not mine. #works-on-my-machine