Corvus Capture

Hotkey-to-file screenshots, zero friction.

Press a key, get a correctly-named, auto-numbered file — no dialogs, no clipboard-first detour, no bloat. Corvus Capture is a lightweight Windows 11 tray utility built for people who screenshot constantly and just want the file to appear.

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Who it's for

• 🧑‍💻 Developers and support engineers who screenshot constantly while documenting bugs, steps, or tasks
• 🪶 Anyone who wants a screenshot tool that idles at effectively zero cost, not a heavyweight suite
• 🔢 People who like task001.png, task002.png… sequential naming, without renaming anything by hand
• 🚫 Anyone tired of ShareX/Snipping Tool/Greenshot's save dialogs, clipboard-first flows, or idle overhead

Features

• 🖥️ Fullscreen capture (F9) — grabs the entire monitor under the cursor, no UI, saved immediately
• 🪟 Active-window capture (Ctrl+F9) — captures only the focused window, using DWM extended frame bounds (not the raw window rect, which includes the invisible drop-shadow border)
• ✂️ Region capture (Shift+F9) — freezes the screen under a ~40% dimmed overlay; drag to select, resize via 8 handles, move by dragging the interior, with a live pixel-dimension readout; confirm with Shift+F9/Enter/double-click, cancel with Esc/an outside click
• ⚙️ Settings (Alt+F9) — raw Win32 window for base filename, save folder, output format, JPG quality, toast/clipboard/shutter-sound toggles, and Start with Windows — every change applies instantly, no restart
• 🔢 Auto-numbering — {base}{NNN}.{ext}, zero-padded to 3 digits and growing past 999 (task1000.png); collisions are always skipped, never overwritten, and deleted numbers are never reused
• 🖼️ Multiple formats — PNG, JPG (quality slider, 50–100), BMP, and lossless WebP
• 📋 Optional clipboard copy — toggle in Settings; the file save always happens regardless
• 🔔 Optional save toast — a small on-screen confirmation ("Saved task004.png"), toggleable
• 🔊 Optional shutter sound — a camera-shutter cue on capture, default off
• 🚀 Start with Windows — self-healing quoted Run key registration, survives moving the exe
• 🎯 Per-Monitor V2 DPI awareness — pixel-accurate captures on mixed-DPI multi-monitor setups
• 🐦‍⬛ Crow tray icon + circular startup splash — lives quietly in the system tray between captures

Settings persist to %APPDATA%\CorvusCapture\config.json and are re-read live, so hand edits to the file apply immediately with no restart.

Footprint

Measured from a clean cargo build --release (see repository 05-FOOTPRINT.md methodology: Get-Counter '\Process(CorvusCapture)\Working Set - Private', 65s+ idle settle, 3 samples).

Metric	Measured	Budget	Method
Exe size	1.13 MB (1,182,720 bytes)	< 5 MB	cargo build --release, direct file size
Idle private working set	1.42 MB (max of 3 samples)	< 10 MB	Get-Counter on the live process, 65s+ settled idle
Idle CPU	0.00%	~0%	Get-Counter '\Process(CorvusCapture)\% Processor Time', 3 samples

No DLLs ship alongside the exe — it is a fully standalone, single portable file.

Known limitations

• Unsigned binary — Windows SmartScreen may show "Windows protected your PC" on first run. Click More info, then Run anyway to launch. Verify the download against the SHA-256 checksum published on the release page before doing so.
• No HDR tone-mapping — capture uses GDI BitBlt, which does not tone-map HDR content correctly and may miss hardware-overlay content. DXGI Desktop Duplication is deferred post-MVP.
• WebP is lossless only — the image crate's WebP encoder has no lossy mode, so the JPG quality slider applies to JPG only.
• Rounded window corners — Windows 11's rounded window corners mean active-window captures include background pixels in the corners, matching Win+PrintScreen's behavior.
• Fixed hotkeys — F9, Ctrl+F9, Shift+F9, and Alt+F9 are not rebindable in v0.1 (rebinding is planned). Note: F9 triggers recalculation in Excel and field updates in Word.
• Windows 11 x64 only — no other platforms are supported.

Architecture

Tray icon + global hotkeys (raw Win32 message pump)
        │
        ├── F9 ────────► fullscreen capture (BitBlt, monitor under cursor)
        ├── Ctrl+F9 ───► active-window capture (DWM extended frame bounds)
        ├── Shift+F9 ──► frozen-screen overlay ──► crop selection
        └── Alt+F9 ────► Settings window (raw Win32, instant apply)
                                │
                                ▼
                     async save pipeline
        (number reserved synchronously, encode on background
         thread, atomic .tmp-then-rename write, PNG/JPG/BMP/WebP)
                                │
                                ▼
                  {base}{NNN}.{ext} on disk

Design highlights

• Raw Win32 message pump instead of winit — smallest binary and idle-RAM footprint for a Windows-only tray app
• tray-icon + global-hotkey (Tauri-maintained) run on the same raw pump thread — no extra windowing framework required
• GDI BitBlt capture, hand-rolled — full control over DPI and multi-monitor handling in ~40 lines
• Numbers are reserved synchronously before async encode, so rapid-fire captures can never collide or overwrite
• Size-optimized release profile (opt-level = "z", fat LTO, single codegen unit, panic=abort, stripped symbols) keeps the exe under 1.2 MB

Build & run

cargo build --release

The resulting binary is at target/release/CorvusCapture.exe.

Pre-built Windows binaries are attached to each release.

License

MIT — see LICENSE.