RoeSnip

An HDR-correct screenshot tool: press PrintScreen, the screen dims instantly, drag a region, annotate, copy or save. On HDR desktops Windows composites in linear scRGB FP16, and legacy tools (Snipping Tool, Lightshot, ShareX's default path) clip or mis-scale that buffer, which is why their screenshots come out washed-out and gray. RoeSnip captures the true FP16 frame and converts it properly.

• HDR done right. SDR content (the common case) comes out pixel-identical to a plain SDR monitor's screenshot: an exact pass-through, matched to the "SDR content brightness" level. Genuine HDR highlights get a smooth, hue-preserving rolloff instead of blowing out. Optionally saves the untouched HDR original as a .jxr alongside the PNG, the way Xbox Game Bar does.
• Instant response. A resident tray process with pre-provisioned capture sessions and overlay windows: the dim lands in single-digit milliseconds and the interactive overlay opens in under 100 ms, warm or cold.
• Annotations. Rectangle, ellipse, arrow, line, freehand, highlighter, pixelate (censor mosaic), and text in any installed font. Every placed shape stays editable: click it under any tool to move it, drag its handles or endpoints, scroll to adjust its stroke/mosaic/font size, with full undo/redo.
• Color picker. A plain click inspects the pixel under the cursor into a compact picker window (hex / RGB / HSL / nits, HDR-aware).
• Screen recording. Record the selected region to MP4 or GIF straight from the overlay toolbar. A small floating control bar shows elapsed time and lets you stop and save or cancel. Pressing PrintScreen again while recording stops and saves it, the same shortcut you used to start it.
• Multi-monitor. One overlay per monitor, per-monitor HDR state and SDR white levels, capture via Desktop Duplication with a Windows.Graphics.Capture fallback per monitor.
• CLI modes. Headless --capture and per-monitor --diag HDR diagnostics, no UI involved.

Quick start

Requires Windows 10 2004+ and the .NET 8 SDK to build (the published exe is self-contained).

dotnet build RoeSnip.sln -c Release
dotnet test RoeSnip.sln

# single-file exe -> src/RoeSnip/bin/Release/.../win-x64/publish/RoeSnip.exe
dotnet publish src/RoeSnip/RoeSnip.csproj -c Release -p:PublishProfile=win-x64

Run RoeSnip.exe with no arguments to start the tray app; PrintScreen opens the capture overlay. If Windows currently intercepts PrintScreen for Snipping Tool, RoeSnip asks once whether to disable that or use Ctrl+PrintScreen instead. The hotkey can be changed later from the tray icon's Settings window. Launching the exe again triggers a capture on the running instance.

Settings live at %APPDATA%\RoeSnip\settings.json (hotkey, save directory, auto-HDR-copy, tone-map overrides, run-at-startup, copy-on-select). A missing or corrupt file falls back to defaults in memory without being overwritten, so it can always be inspected or repaired by hand.

CLI

RoeSnip.exe --diag
RoeSnip.exe --capture [--monitor N] [--out shot.png] [--jxr]

• --diag prints per-monitor diagnostics (device, resolution, Advanced Color on/off, SDR white level, max luminance) and exits.
• --capture captures one or all monitors headlessly, writes PNGs, prints min/max/avg captured nits, and with --jxr also writes the untouched HDR original next to each PNG.

Linux

The cross-platform build (src/RoeSnip.App) publishes a self-contained linux-x64 binary or AppImage. Run it with no arguments to start the tray app, or ./RoeSnip capture / ./RoeSnip settings to trigger the capture flow or open the settings window (starting a resident instance on first run, signaling the existing one afterward).

Global hotkeys do not work on Wayland. RoeSnip's hotkey hook (SharpHook/libuiohook) is X11-only, so on a stock GNOME or KDE Wayland session pressing PrintScreen does nothing — RoeSnip detects this at startup and never even tries to start the hook. The app shows a one-time notice about it and stays fully operable; the fix is to bind a desktop-environment keyboard shortcut to the RoeSnip capture CLI verb:

• GNOME: Settings → Keyboard → View and Customize Shortcuts → Custom Shortcuts → add one with command /path/to/RoeSnip capture.
• KDE: System Settings → Shortcuts → Custom Shortcuts → add a new global shortcut that runs /path/to/RoeSnip capture.

X11 sessions are unaffected — the hook starts normally there and the PrintScreen hotkey works as on Windows.

Docs

• DESIGN.md: behavioral spec covering capture paths, tone mapping, overlay semantics, and failure modes.
• PLAN.md: the implementation plan the WPF app was built against.
• DESIGN-XPLAT.md / PLAN-XPLAT.md: the in-progress cross-platform port (src/RoeSnip.App, Avalonia + RoeSnip.Core + RoeSnip.Platform.*) targeting Linux (X11) and macOS (helpers/scksnap). The WPF app in src/RoeSnip is the Windows daily driver.
• TESTING.md: what has actually been verified, per OS and how.