Keyboard Glow Visualizer

A macOS application that displays colorful glowing borders around your screen when you type. Each keypress triggers a vibrant, randomly-colored glow effect that fades smoothly over time.

Features

• Full-screen border glow - 20px colored borders on all four sides of the usable screen area
• Random vibrant colors - Uses HSV color space to generate saturated, bright colors
• Smooth fade animation - Colors fade out over 1.5 seconds with additive blending
• Layered effects - Multiple keypresses stack with additive blending for dynamic color mixing
• Semi-transparent window - See through the center while borders remain visible
• Lightweight - Simple SDL2-based rendering with VSync support

Requirements

• macOS
• SDL2 library
• C++ compiler with C++11 support

Installation

1. Install SDL2

Using Homebrew:

brew install sdl2

2. Clone the repository

git clone https://github.com/yourusername/KeyboardGlowVisualizer.git
cd KeyboardGlowVisualizer

3. Build

make

Usage

Run the application:

./glow

• Type while the window is focused to see the glow effects
• Press ESC to quit

Configuration

You can modify these constants at the top of main.cpp:

Constant	Default	Description
BORDER_THICKNESS	20	Width of the border in pixels
FADE_DURATION	1500	How long glows take to fade (milliseconds)

To adjust window transparency, modify the opacity value in SDL_SetWindowOpacity():

SDL_SetWindowOpacity(window, 0.3f);  // 0.0 = invisible, 1.0 = fully opaque

How It Works

1. Window Creation - Creates a borderless window covering the usable screen area (excludes menu bar and dock)
2. Color Generation - On each keypress, generates a random color using HSV with high saturation (0.8-1.0) and value (0.8-1.0) for vibrant results
3. Rendering - Draws four border rectangles with additive blending, allowing colors to mix when multiple glows are active
4. Animation - Each glow's alpha decreases linearly over the fade duration until it's removed

Project Structure

KeyboardGlowVisualizer/
├── main.cpp          # Main application source
├── Makefile          # Build configuration
├── create_app.sh     # Script to create macOS .app bundle
└── README.md         # This file

Makefile Commands

Command	Description
make	Build the application
make clean	Remove build artifacts
make run	Build and run
make rebuild	Clean and rebuild
make app	Create macOS .app bundle

Known Limitations

• Requires focus - The window must be focused to receive keyboard input. Global keyboard monitoring requires accessibility permissions and additional macOS frameworks.
• Semi-transparent only - True transparency (fully transparent center with opaque borders) is not supported by SDL2 on macOS. The entire window shares the same opacity level.

License

MIT License - Feel free to use and modify as you like.

Contributing

Pull requests welcome! Some ideas for improvements:

• Add command-line arguments for configuration
• Support multiple color schemes/palettes
• Add audio-reactive mode
• Implement different glow patterns (pulse, wave, etc.)