YAKD: Open‑Source Utility to Show Keyboard & Mouse Input in Real TimeYAKD (Yet Another Key Displayer) is a small open‑source utility designed to show keyboard and mouse input on screen in real time. It’s aimed at developers, educators, streamers, and anyone who records or demonstrates software and wants viewers to see exactly what keys and mouse actions are being pressed. This article covers YAKD’s purpose, core features, typical use cases, configuration and customization options, implementation details, performance and privacy considerations, and community and development notes.
What YAKD does and why it exists
YAKD displays an unobtrusive overlay that visualizes key presses and mouse actions as they happen. Unlike more complex input-capture suites, YAKD focuses on clarity, low overhead, and configurability. The principal motivations behind YAKD are:
- To make tutorials, screencasts, and live streams more informative by showing viewer-visible input.
- To provide a tiny, dependency-light tool that’s easy to configure.
- To offer an open-source alternative that can be adapted for specific workflows, accessibility scenarios, or research.
Key idea: YAKD’s overlay mirrors the user’s input in real time so audiences can follow along without guessing which keys or mouse buttons are used.
Core features
- Real-time visualization of keyboard keys and mouse buttons/movement.
- Configurable overlay position, opacity, color, size, and styling.
- Support for highlighting modifier keys (Ctrl, Alt, Shift, Meta) and sequences (e.g., Ctrl+C).
- Option to show key press durations or simple press/release flashes.
- Toggleable display per-input type: keyboard only, mouse only, or both.
- Low CPU and memory footprint; designed for live use alongside recording/streaming software.
- Cross-platform builds (common targets: Windows, macOS, Linux) or easily portable code for single-platform users.
- Keyboard layout awareness (e.g., QWERTY vs AZERTY) and support for Unicode keys where platform APIs permit.
- Simple hotkeys to show/hide the overlay or change modes while streaming.
- Theme and plugin support (for community extensions like showing gamepad input or advanced analytics).
Typical use cases
- Tutorials and screencasts: In software tutorials it’s common for instructors to reference complex key combos. YAKD makes those combos visible.
- Live coding and pair programming: Viewers can follow the demonstrator’s exact keystrokes.
- Game streaming and speedruns: Displaying keypresses can be helpful for explaining techniques.
- Accessibility demonstrations: Showing input can aid users learning alternative input methods.
- Usability testing and debugging: Developers can record sessions with visible input for later analysis.
Configuration and customization
YAKD aims to be flexible so users can tailor it to their needs. Common configurable elements:
- Overlay placement: corners, center, or fixed coordinates.
- Display modes:
- Instant flash (briefly highlights pressed keys).
- Persistent display (keys stay visible while pressed).
- Timeline mode (shows recent sequence of keys).
- Visual styling: font, key shape (rounded rectangle, pill), color schemes, transparency.
- Modifier behavior: group modifiers or show each separately.
- Aggregation rules: compress sequences like Ctrl+Shift+P into one combined badge.
- Input filters: ignore mouse movement-only noise, filter certain keys (e.g., media keys), or restrict display to a single application.
- Export/record mode: embed current input overlay in produced video frames or output a separate log file with timestamps.
- Scripting hooks or plugin API: react to events (e.g., display message when a specific key sequence is pressed).
Configuration can be exposed through a GUI, a simple JSON/YAML config file, or command-line flags for scripting and automation.
Implementation details (architecture and considerations)
A typical YAKD implementation is small but requires careful handling of system input APIs and on-screen overlays:
- Input capture:
- Windows: low-level keyboard and mouse hooks (SetWindowsHookEx with WH_KEYBOARD_LL, WH_MOUSE_LL) or Raw Input APIs.
- macOS: CGEventTap or other CoreGraphics event APIs.
- Linux: evdev for direct device access, X11’s XRecord/XInput2 for display server, or libinput on Wayland compositors that support it.
- On-screen overlay:
- Use the native windowing stack to create a borderless, always-on-top, transparent window that renders the overlay.
- Consider using hardware-accelerated rendering (OpenGL, Direct2D, Metal, or GPU-backed toolkits) for smooth updates with minimal CPU load.
- Cross-platform portability:
- Structure code with platform abstraction layers: input capture, windowing/graphics, configuration, and UI.
- Use a small cross-platform library where useful (SDL2, GLFW, or a minimal GUI toolkit) while avoiding heavy dependencies.
- Input processing:
- Debounce and rate-limit noisy events; handle auto-repeat vs discrete presses correctly.
- Map key codes to visible labels respecting system keyboard layout and locale.
- Security and privacy:
- Avoid logging or transmitting keystrokes by default. If an output/log is provided, make it explicit and opt-in.
- Make clear that the tool requires input-capture permissions (on macOS, accessibility permissions; on Windows, appropriate privileges) and explain how to revoke them.
Performance and reliability
YAKD should have negligible impact on common streaming/recording setups:
- Keep rendering loop efficient (redraw only when events occur).
- Use GPU acceleration to avoid stuttering.
- Profile across platforms to ensure key events are captured with minimal latency.
- Provide an option for lower‑power/resolution rendering on older hardware.
Testing should include scenarios with rapid key presses (e.g., gaming), long modifier holds, and multiple concurrent input devices.
Privacy, security, and ethics
Visualizing keystrokes can reveal sensitive input. Design guidelines:
- Default to privacy-safe settings: do not capture or export key logs by default.
- Provide a clear visual indicator when capture is active.
- Offer granular filters (suppress password fields or hide input from specific apps).
- Warn users about the risks of showing passwords or private data during streams or recordings.
Community, licensing, and contribution
An open-source project like YAKD benefits from community contributions:
- License: permissive licenses (MIT, Apache 2.0) encourage adoption and forks; GPL variants ensure copyleft — choose based on project goals.
- Contribution areas: platform ports, themes, plugin modules (gamepad, OSC output), documentation, localization, and accessibility improvements.
- Distribution: provide binaries for common OSes, package in popular repositories (Homebrew, AUR, Chocolatey), and offer containerized or portable builds.
- Issue tracking and feature requests: maintain a public issue tracker and a roadmap for prioritizing work.
Example practical setup
A simple recommended setup for a screencaster:
- Install YAKD for your OS.
- Configure overlay near the bottom-left with semi-transparent dark background and a medium font size.
- Enable combined-modifier aggregation and persistent display mode.
- Add a hotkey (e.g., Ctrl+Alt+Y) to toggle overlay visibility while recording.
- Test with your streaming software (OBS/Streamlabs) and confirm the overlay appears in the captured window or as a separate window source.
Roadmap ideas and extensions
- Gamepad and joystick input visualization.
- Networked mode: stream input events to a co-present collaborator or judge in real time (with secure, opt-in transport).
- Advanced analytics: heatmaps of most-used keys during a session.
- Scene-aware modes: detect when a recording/stream starts and auto-enable/disable overlay.
- Browser extension variant: display keys inside browser-based recordings without native installs.
Conclusion
YAKD fills a small but valuable niche: making on-screen demonstrations clearer by showing exactly what keys and mouse actions are being performed. Its value increases when it remains lightweight, privacy-conscious, and easy to customize. For streamers, educators, and developers producing recorded or live content, YAKD-style tools reduce cognitive overhead for viewers and improve the clarity of tutorials and demos.
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