Flapline

A split-flap screensaver with somewhere to be.

Flapline brings the soft shuffle of old airport and train-station departure boards to your Mac. It flips, drifts, clicks through messages, shows the time or date, and then gets out of the way when the screen saver is not running.

Built in Swift with macOS ScreenSaver, Core Animation, and a small affection for mechanical things that do one job beautifully.

What It Does

• Custom messages: add one phrase per line and let the board rotate through them.
• Clock and date modes: run it like a quiet desk clock or a calendar board.
• Unicode support: accents, symbols, and emoji can ride along with the classic flap alphabet.
• Themes: classic amber, terminal green, monochrome, and room for more.
• Idle-friendly animation: Core Animation drives the flip work, and the display clock stops when the saver is not visible.
• Private by default: configuration stays on your Mac. No account, no network service, no telemetry.

Download

Public releases will live on GitHub Releases and at https://flapline.app.

Until the first signed release is published, build from source:

make install

That builds a Release copy and installs it into:

~/Library/Screen Savers/Flapline.saver

Configure

Open System Settings -> Screen Saver, choose Flapline, then open Options.

The options sheet lets you tune:

• Display: random board, custom messages, clock, or date
• Messages: one message per line, including Unicode text and emoji
• Message order: sequential or random
• Wave interval: how often the board updates
• Idle shuffle: whether panels drift between coordinated waves
• Board rows: approximate display density
• Theme: classic amber, terminal green, or monochrome

The original split-flap alphabet still animates through a mechanical forward drum sequence. Other Unicode grapheme clusters render directly as valid panel targets.

Build

Requirements:

• macOS 12 or later
• Xcode 14 or later

Make targets:

make build         # Release build
make debug         # Debug build
make install       # Build and install to ~/Library/Screen Savers/
make install-debug # Debug install
make uninstall     # Remove the installed saver
make preview       # Open the Screen Saver settings pane

Xcode:

1. Open SplitFlap.xcodeproj.
2. Select the SplitFlap scheme.
3. Build.
4. Copy Flapline.saver from the build products into ~/Library/Screen Savers/.

Website

The public site is intentionally small and static:

website/

It is configured for the single canonical domain:

flapline.app

No www site is planned.

Release Notes For Humans

For public distribution, Flapline should be Developer ID signed and notarized before release. Unsigned local builds are fine for development, but public downloads should avoid scary Gatekeeper warnings.

See docs/release/public-launch.md for the domain, signing, website, and release checklist.

Project Structure

Path	Purpose
SplitFlap/	Screensaver source code
SplitFlap/Info.plist	Bundle metadata and principal class
SplitFlap.xcodeproj	Xcode project
website/	Static public website for flapline.app
scripts/ci/	Fast, extended, and release validation scripts
docs/release/	Public launch and release guidance

Part of OMT Global

Flapline is a small father-and-son open-source project with an unnecessary amount of care put into tiny moving panels.