ddc-gui

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Lightweight system tray brightness controller for external monitors on Linux using DDC/CI.

Most Linux desktop environments lack a simple and reliable way to control external monitor brightness via DDC/CI. This project aims to provide a minimal, fast, and native-feeling solution.

✨ Features

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• Tray (AppIndicator) integration
• Quick brightness presets
• Precision control with popup slider
• Minimal and lightweight (GTK3 based)
• Works with ddcutil

📸 Screenshots

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Preset Menu	Slider

⚙️ Requirements

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• Linux (X11)
• ddcutil
• Python 3
• GTK 3 bindings (python3-gi)
• libayatana-appindicator3

Install dependencies (Debian/Ubuntu)

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sudo apt install ddcutil python3-gi gir1.2-gtk-3.0 gir1.2-ayatanaappindicator3-0.1

🚀 Usage

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Before running, verify your monitor is detected:

ddcutil detect

python3 main.py

🔄 Autostart

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To start the application automatically on login, create a .desktop entry:

mkdir -p ~/.config/autostart
nano ~/.config/autostart/ddc-gui.desktop

Paste the following:

[Desktop Entry]
Type=Application
Name=ddc-gui
Exec=python3 /full/path/to/main.py
Icon=display-brightness-symbolic
Terminal=false
X-GNOME-Autostart-enabled=true

Replace /full/path/to/main.py with the actual path to your project.

Alternative (Recommended)

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If you install the app system-wide, you can simplify:

Exec=/usr/bin/python3 /full/path/to/main.py

Notes

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• Make sure the script is executable:

  chmod +x main.py

• Some desktop environments may require logout/login after setup.

• Make sure your user has permission to access I2C devices (usually by being in the i2c group).

⚠️ Known Issues

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• Bus ID is currently hardcoded
• Brightness is not synced on startup
• Limited multi-monitor support
• Error handling is minimal

🗺️ Roadmap

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• Auto-detect monitor (DDC bus)
• Sync current brightness on startup
• Multi-monitor support
• Config file support
• Packaging (.deb)
• Improved error handling

📜 License

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GPLv3 License

🤝 Contributing

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Contributions, issues and suggestions are welcome.