✨ Glint

DDC display control from your keyboard. Tiny, invisible, always ready.

Glint intercepts your Mac's brightness and volume media keys and sends DDC/CI commands to your external monitor — so the keys that normally only control your MacBook screen now also control your monitor's actual hardware brightness and built-in speakers.

🪶 Under 1 MB. No Electron. No frameworks. Pure Swift + IOKit. Zero CPU when idle. Disappears completely if you want it to.

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🎯 Why Glint Exists

If you've ever plugged an external monitor into your Mac, you know the pain:

• Brightness keys? Only control the MacBook screen.
• Volume keys? Only control the Mac speakers — not the monitor's.
• The fix? Reach for clunky OSD buttons on the back of your monitor. Every. Single. Time.

Glint makes your keyboard Just Work™ with external displays.

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⚡ Features

Feature	Details
🔆 Brightness keys	Controls your external display's backlight via DDC — not software gamma
🔊 Volume keys	Adjusts volume via DDC when audio output is HDMI/DisplayPort/USB-C (including hubs), or system volume for built-in speakers/headphones/Bluetooth
🔇 Mute key	Toggles mute with a proper muted/unmuted OSD indicator
🎯 Cursor-aware	Brightness keys adjust only the display the cursor is on — no more changing every screen at once
🔄 Sync mode	First keypress syncs all displays to match the cursor display's brightness, then adjusts every screen in lockstep
🖥️ Subtle OSD	Shows a minimal pill-style brightness/volume overlay below the notch
👻 Invisible mode	Hide from menu bar AND dock — completely invisible, always listening
🚀 Launch at login	Starts silently, ready before you are
🪶 Tiny footprint	< 1 MB, zero dependencies, negligible CPU/memory
🆓 Free & open source	MIT License. No telemetry. No accounts. No nonsense.

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📦 Install

Homebrew

brew install --cask blaineam/tap/glint

Download

Grab the latest notarized DMG from Releases — drag to Applications, done.

Build from source

# Install xcodegen if you don't have it
brew install xcodegen

# Generate the Xcode project
xcodegen generate

# Build
xcodebuild -scheme Glint -configuration Release build

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🛠️ Setup

1. Open Glint — it appears in your menu bar as a ☀️ icon
2. Grant Accessibility access when prompted (System Settings → Privacy & Security → Accessibility)
3. Quit and relaunch Glint after enabling Accessibility access
4. Press your brightness/volume keys — they now control your external display!

Going invisible

Toggle "Hide menu bar icon" in Settings. Glint vanishes from the menu bar and dock entirely. To access settings again, just open Glint from your Applications folder — it'll show the settings window.

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🔧 How It Works

┌──────────────┐    CGEventTap     ┌──────────────┐    IOKit I2C     ┌──────────────┐
│   Keyboard   │ ───────────────▶  │    Glint     │ ──────────────▶ │   Monitor    │
│  Media Keys  │   intercept key   │  (< 1 MB)    │   DDC/CI cmd    │  Hardware    │
└──────────────┘                   └──────────────┘                 └──────────────┘
                                         │
                                         │ (sync mode)
                                         ▼
                                   Programmatic control
                                   of built-in display
                                   brightness & system
                                   volume via IOKit/CoreAudio

1. CGEventTap intercepts and fully consumes media key events — no macOS OSD ever appears
2. DDC/CI commands are sent over the I2C bus (via IOAVService on Apple Silicon) to adjust hardware brightness/volume on external displays
3. Cursor-aware: when sync is off, only the display the cursor is on is adjusted — built-in or external
4. Sync mode (on by default): Glint programmatically adjusts the built-in display brightness (via IOKit) and system volume (via CoreAudio) alongside external monitors — all stay in lockstep
5. First-keystroke sync: when sync is enabled, the first key press reads the cursor display's current brightness and forces all other displays to match before adjusting together

Why not the Mac App Store?

DDC requires direct I2C communication through IOKit, which is blocked by the App Store sandbox. This is why every DDC app (BetterDisplay, MonitorControl, Lunar) distributes outside the App Store. Glint is notarized by Apple for security — it's just not sandboxed.

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🏗️ Project Structure

Glint/
├── Sources/
│   ├── App/
│   │   ├── GlintApp.swift              # SwiftUI entry point, menu bar setup
│   │   └── Glint-Bridging-Header.h     # IOKit I2C headers
│   ├── Services/
│   │   ├── DDCService.swift            # IOKit I2C DDC/CI communication
│   │   ├── DisplayManager.swift        # Display enumeration, brightness/volume control
│   │   ├── MediaKeyInterceptor.swift   # CGEventTap media key interception
│   │   ├── OSDOverlay.swift            # Native overlay HUD
│   │   └── Preferences.swift           # UserDefaults + launch-at-login
│   └── Views/
│       ├── MenuBarView.swift           # Popover with per-display sliders
│       └── SettingsView.swift          # Settings window
├── Resources/
│   ├── Assets.xcassets/                # App icon, accent color
│   ├── Info.plist
│   └── Glint.entitlements
├── Scripts/
│   ├── generate-assets.swift           # Programmatic icon + DMG background generator
│   ├── build-dmg.sh                    # Full build → sign → notarize → DMG pipeline
│   └── notarize.sh                     # Standalone notarization script
├── docs/                               # GitHub Pages site
├── project.yml                         # XcodeGen project spec
├── LICENSE                             # MIT
└── README.md

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🤝 Contributing

Contributions welcome! Here's how to get started:

1. Fork & clone the repo
2. Install xcodegen: brew install xcodegen
3. Generate the project: xcodegen generate
4. Open Glint.xcodeproj in Xcode
5. Build & run — you'll need an external monitor with DDC support to test

Guidelines

• Keep it tiny — Glint's value is in its simplicity and small footprint
• No third-party dependencies — pure Swift + system frameworks
• Match the existing code style (no SwiftLint, just be consistent)
• Test with real hardware — DDC behavior varies across monitor brands
• Open an issue first for large changes so we can discuss the approach

Reporting issues

If DDC doesn't work with your monitor:

1. Enable Debug logging in Settings
2. Try adjusting brightness/volume
3. Click Show Log File to find the log
4. Include the log along with your monitor make & model, connection type, macOS version, and whether other DDC apps work

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📋 FAQ

Does Glint work with my monitor?

Most external monitors support DDC/CI. If your monitor has an OSD (on-screen display) with brightness/volume controls, it almost certainly supports DDC. Known exceptions: some older Apple displays and a few budget monitors with DDC disabled by default (check your monitor's OSD settings).

Does it work over HDMI? DisplayPort? USB-C?

Yes to all three. DDC/CI works over HDMI, DisplayPort, and USB-C/Thunderbolt — including through USB-C hubs and docks. Glint automatically detects monitor audio routed through hubs by matching the audio device name against connected displays.

Why does Glint need Accessibility access?

To intercept media key events (brightness, volume) before macOS processes them, Glint uses a CGEventTap, which requires Accessibility permission. Without it, Glint can't detect key presses.

Is this safe? Why isn't it on the Mac App Store?

Glint is open source (read every line!) and notarized by Apple (malware-scanned). It's not on the App Store because DDC requires IOKit I2C access, which the App Store sandbox blocks. This is the same reason BetterDisplay, MonitorControl, and Lunar are all distributed outside the store.

How do I access settings after hiding the menu bar icon?

Open Glint from your Applications folder (or Spotlight). When the app detects it's being re-opened, it shows the settings window automatically.

Can I control multiple monitors?

Yes! Glint detects all connected external displays. With sync mode off, brightness keys adjust only the display your cursor is on. With sync mode on, all displays (including the built-in screen) are adjusted together and synced to the same brightness on first key press.

Does it conflict with BetterDisplay / MonitorControl / Lunar?

Possibly — if two apps both intercept the same media keys, they may interfere. We recommend using one DDC controller at a time.

What's the CPU/memory usage?

Effectively zero when idle. Glint uses a CGEventTap which is interrupt-driven — no polling, no timers, no background threads. Memory footprint is under 15 MB.

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📄 License

MIT License — see LICENSE.

Free as in beer. Free as in speech. 🍺

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_{Built with ☀️ by Blaine Miller}