SpinWin

A macOS menubar utility that visually rotates a selected window by any angle (90° increments, arbitrary angles, or a continuous spin).

Why does this exist?

I was wasting time watching short-form videos (Reels, YouTube Shorts, that sort of thing) on my Mac when one asked the viewer to turn their "phone" upside down. You can't do that with a Mac. SpinWin is the result.

How it works

macOS has no public API to rotate another app's window. Real rotation would require private SkyLight calls (CGSSetWindowTransform) with System Integrity Protection disabled — not worth it.

Instead, SpinWin fakes it:

1. Hide the selected window off-screen via the Accessibility API. It keeps rendering there, so it can still be captured.
2. Capture its contents continuously with ScreenCaptureKit (SCStream + desktopIndependentWindow filter) — this grabs only that window's buffer, so the overlay never mirrors itself.
3. Draw the frames in a transparent, borderless overlay window placed where the original was, rotated with a CALayer transform.

Because it's a layer transform, any angle works — the overlay is sized to the rotated content's bounding box so nothing clips, and a diagonal-sized square is used while spinning.

Usage

The easiest way to get SpinWin is the latest release — the download is signed with a Developer ID and notarized by Apple, so it launches without Gatekeeper warnings. Or build it yourself:

./scripts/build-app.sh          # builds SpinWin.app (release)
open SpinWin.app              # grant Screen Recording + Accessibility

For quick iteration during development:

swift build && swift run SpinWin

Left-click the menubar icon to start: choose a rotation in the bottom options bar (a preset angle, a spin speed + direction, or free rotation), then click the window you want. Drag the overlay to reposition it; drag its handle to rotate freely. Press Esc on the overlay to stop and restore the window.

Right-click (or Control-click) the icon for the menu: active rotations (with per-window angle/spin controls), Stop all, and Quit.

Permissions

• Screen Recording — to capture the window contents.
• Accessibility — to move the source window off-screen and restore it.

Current limitations

• The overlay is a live picture, not interactive. You can drag and rotate it, but clicks and keystrokes are not sent to the real window underneath.
• Mission Control / Exposé leak. The hidden window is parked off-screen but still a real window, so Exposé shows it unrotated. There is no public API to exclude another app's window from Mission Control, and minimizing it would stop the capture.
• Some apps throttle rendering of off-screen windows, which can slow the feed.
• A window that resizes itself while rotated keeps its original footprint. You can't drag-resize the hidden window, but an app can still resize it on its own (a video player adapting to a new track, a terminal responding to an escape sequence). The capture is letterboxed into the original size until you stop and rotate it again.

Layout

File	Role
main.swift	App entry point (accessory/menubar policy)
AppDelegate.swift	Menubar item; left-click rotates, right-click opens menu
Permissions.swift	Requests Screen Recording + Accessibility at launch
WindowPicker.swift	Full-screen window picker + rotation options bar
RotationManager.swift	Tracks one rotation session per window
RotationSession.swift	Orchestrates hide → capture → overlay per window
CaptureEngine.swift	ScreenCaptureKit stream → IOSurface frames
OverlayWindow.swift	Transparent rotating/spinning overlay, drag
AccessibilityWindowMover.swift	Move source window off-screen + restore
ActivationChoice.swift	Initial rotation choice (angle/spin/free)
SpinDirection.swift	Clockwise/counterclockwise spin option
MenuBarIcon.swift	Draws the menubar icon
AboutWindow.swift	About window (icon, version, author, GitHub link)