capscr

HDR-aware screen capture for Windows and Linux. Tray-first, signed updates, no telemetry.

• homepage: rot.lt/work/capscr
• plugins: rot.lt/work/capscr/plugins, registry at zeo/capscr-plugins
• downloads: GitHub Releases
• license: MIT

features

Every hotkey is a task: a capture mode (region, region-last, window, fullscreen, active monitor, region GIF, region MP4) plus a post-action (save, clipboard, editor, annotate, upload, OCR). Bind as many as you want in the hub.

The selection overlay does region drag, window click, Enter for fullscreen, and Alt+click to copy a pixel's #RRGGBB. Live size readout, 8x loupe, window-snap highlight.

HDR capture (Windows) goes through Windows.Graphics.Capture FP16 with an ICtCp luminance-only tonemap and per-monitor SDR-white detection. Output is SDR PNG, or HDR-preserved PNG (PQ cICP / HLG). Linux compositors don't expose HDR pixels to capture clients yet, so Linux captures are SDR.

Recording produces GIF or H.264 MP4 (ffmpeg, auto-downloaded and sha256-verified on Windows; system ffmpeg on Linux), with a live timer and stop control drawn outside the captured area.

Uploads go to Imgur, custom HTTPS POST, SFTP, or S3. Destinations pass SSRF checks (DNS double-resolve, private-IP rejection), and stored passwords live in the platform credential vault (DPAPI / Secret Service), never on disk in cleartext. Plain FTP is rejected because it leaks credentials in transit.

Updates are in-place, Minisign-signed, through the shared rot installer. deb and rpm installs update through the system package manager.

install

Grab a file from the releases page:

file	use
capscr-x.x.x-online-setup.exe	signed Windows bootstrapper, downloads the verified package
capscr-x.x.x-offline-setup.exe	signed Windows installer, package embedded
capscr-x.x.x-linux-x86_64-setup	Linux bootstrapper
capscr-x.x.x-linux-x86_64-offline-setup	Linux offline installer
capscr_x.x.x_amd64.deb	Debian / Ubuntu / Mint
capscr-x.x.x-1.x86_64.rpm	Fedora / openSUSE
capscr_x.x.x_amd64.AppImage	any glibc 2.39+ distro; chmod +x and run

Needs Windows 10 1903+, or a Linux desktop with webkit2gtk 4.1 and glibc 2.39+. MP4 recording uses ffmpeg, OCR uses tesseract, X11 file-clipboard uses xclip; the deb and rpm pull these in as recommends.

X11 and Wayland both work. Wayland picks a pixel source per compositor (KWin ScreenShot2, ext-image-copy-capture on wlroots, portals on GNOME):

feature	X11	KDE Wayland	wlroots Wayland	GNOME Wayland
capture, editor, upload, GIF + MP4	✅	✅	✅	✅
window picking	capscr overlay	KWin picker	capscr overlay	portal picker
keyboard global hotkeys	✅	✅	portal, else Advanced input	✅
mouse side-button hotkeys	Advanced input	Advanced input	Advanced input	Advanced input
recording bar above fullscreen	✅	✅	✅	best-effort
tray icon	✅	✅	depends on host	needs AppIndicator
HDR-preserved capture	no	no	no	no

Advanced input (Settings → hotkeys) reads /dev/input directly and needs the input group; it covers mouse buttons everywhere and keyboards on portalless compositors. The "no" row needs compositor-side changes, written up in docs/platform-limits.md.

default hotkeys

hotkey	action
set on first launch	region → save + clipboard
Ctrl+Shift+G	region GIF → save
Ctrl+Shift+V	region MP4 → save

All rebindable in the Tasks tab.

configuration

%APPDATA%\capscr\capscr\config\config.toml on Windows, ~/.config/capscr/config.toml on Linux. The hub edits everything, but the file is plain TOML:

[capture.hdr]
brightness_nits = 0.0        # SDR-white override; 0 = auto-detect
user_brightness_scale = 1.0  # pre-tonemap exposure multiplier

[upload]
destination = "Imgur"        # or "Custom" / "Sftp" / "S3"
copy_url_to_clipboard = true

[upload.sftp]
host = "files.example.com"
port = 22
username = "user"
password = "secret"          # moved into the credential vault on first save
remote_dir = "/screenshots"
public_url_template = "https://files.example.com/{filename}"

SFTP takes Ed25519 and ECDSA keys via private_key_path. RSA is off until RUSTSEC-2023-0071 is resolved upstream.

build from source

Rust 1.94+, Node 22.12+, MSVC build tools on Windows or the webkit2gtk stack on Linux.

git clone https://github.com/zeo/capscr.git
cd capscr
npm --prefix frontend ci
cargo install tauri-cli --version "^2" --locked
cargo tauri build

Debian/Ubuntu build dependencies:

sudo apt install build-essential curl wget file pkg-config libssl-dev \
  libgtk-3-dev libwebkit2gtk-4.1-dev libayatana-appindicator3-dev \
  librsvg2-dev libxdo-dev libclang-dev libxcb1-dev libxcb-shm0-dev \
  libxcb-randr0-dev libxrandr-dev libdbus-1-dev libpipewire-0.3-dev \
  libwayland-dev libegl-dev libgbm-dev libdrm-dev

Release builds sign packages and manifests with TAURI_SIGNING_PRIVATE_KEY / TAURI_SIGNING_PRIVATE_KEY_PASSWORD.

plugins

The plugins tab browses rot.lt/capscr/registry.json, verifies each zip's sha256, and installs into the app data dir. WASM plugins get on_capture, on_capture_saved, and on_upload_success hooks with capability-gated host imports; see docs/plugin-runtime.md and the publishing contract in docs/marketplace.md.

credits

The HDR tonemap in src/capture/tonemapping.rs is a Rust port of the SKIV ICtCp luminance-only tonemap by Andon "Kaldaien" Coleman (MIT): https://github.com/SpecialKO/SKIV. Per-frame MaxCLL / P99 logic adapted from GotoFinal's HDR tonemap reference (MIT).

license

MIT, see LICENSE.