Show HN: Macpad – turn your game controller into a Mac mouse and keyboard

1 point

a month ago

  I cloud game on my Mac plugged into an external display — controller in
  hand, couch mode, trackpad halfway across the room. Which works fine until
  something interrupts: a Slack ping, a browser tab I need to click, a
  password field.

  Every interruption used to mean pausing, standing up, grabbing the trackpad,
   doing the one-second task, putting the trackpad back, rebinding my hands on
   the controller, and finding my place in the game. The interruption was
  always an order of magnitude longer than the thing it actually interrupted.

  Macpad collapses it into one button. Press Home/PS → the left stick becomes
  my cursor, A is left click, and there's an on-screen keyboard an L1+R1 chord
   away if I need to type. Do the thing. Press Home again → back to the game,
  zero context lost.

  That's the whole pitch. Not a trackpad replacement for its own sake — a fast
   context switch between "I'm gaming" and "I'm on my Mac", without standing
  up.

  The interesting engineering bit, if you're into that: Apple's driver
  silently hides the PS button from the GameController framework on macOS.
  GCController.physicalInputProfile lists "Button Home" but its
  pressedChangedHandler never fires — the OS swallows the event for its Game
  Center overlay. But the button isn't gone. It's right there in the raw HID
  input report.

  Chromium's WebHID does exactly this: opens the device with
  IOHIDDeviceRegisterInputReportCallback, reads the full 64-byte input report,
   and masks the button bit itself. So I did the same — byte 6 bit 0 on DS4
  USB, byte 9 bit 0 on DualSense Bluetooth, etc. Same trick unlocks the
  Create/Share button and the touchpad click, which Apple's driver also drops
  on the floor.

  Other rabbit holes that were way more interesting than I expected:

  - Left clicks turning into right clicks. Posting ⌃Tab via CGEvent leaks the
  control flag into macOS's combined-session modifier state. The next
  synthetic mouse click inherits ctrl, and on macOS ctrl+click == right-click.
   Fix: explicitly reset flags = [] on mouse events, let keyboard events keep
  inheriting (otherwise you break system shortcuts).
  - L1+R1 chord for the keyboard, with a 150ms window. Quick-tapped shoulders
  must still fire their normal action; the chord only wins if both arrive
  inside the window. Deferred-DispatchWorkItem + cancel-on-opposite-arrival.
  - Haptics that actually feel like a mechanical click = a sharp transient
  layered over a 40ms continuous tail. One event alone feels like a flat buzz.
   Two layered events feel like a keycap.

  Honest disclosure: a lot of this was vibe-coded with Claude. I drove, Claude
   did plenty of the typing. I'm calling that out because the interesting
  thing isn't that I hand-wrote every line — it's that the debugging stories
  above (the PS button, the modifier leak, the chord window timing) are all
  real problems we actually hit, diagnosed from logs, and fixed. The AI was a
  good typist; the system design, the "wait, why does this work in Chromium
  but not us", the hypothesis-forming — still the work.

  Works on macOS 14+, Liquid Glass UI on Tahoe, Swift Package Manager, no
  dependencies. MIT.

  Repo + full bindings + architecture notes:
  https://github.com/henit-chobisa/macpad

I cloud game on my Mac plugged into an external display — controller in hand, couch mode, trackpad halfway across the room. Which works fine until something interrupts: a Slack ping, a browser tab I need to click, a password field. Every interruption used to mean pausing, standing up, grabbing the trackpad, doing the one-second task, putting the trackpad back, rebinding my hands on the controller, and finding my place in the game. The interruption was always an order of magnitude longer than the thing it actually interrupted. Macpad collapses it into one button. Press Home/PS → the left stick becomes my cursor, A is left click, and there's an on-screen keyboard an L1+R1 chord away if I need to type. Do the thing. Press Home again → back to the game, zero context lost. That's the whole pitch. Not a trackpad replacement for its own sake — a fast context switch between "I'm gaming" and "I'm on my Mac", without standing up. The interesting engineering bit, if you're into that: Apple's driver silently hides the PS button from the GameController framework on macOS. GCController.physicalInputProfile lists "Button Home" but its pressedChangedHandler never fires — the OS swallows the event for its Game Center overlay. But the button isn't gone. It's right there in the raw HID input report. Chromium's WebHID does exactly this: opens the device with IOHIDDeviceRegisterInputReportCallback, reads the full 64-byte input report, and masks the button bit itself. So I did the same — byte 6 bit 0 on DS4 USB, byte 9 bit 0 on DualSense Bluetooth, etc. Same trick unlocks the Create/Share button and the touchpad click, which Apple's driver also drops on the floor. Other rabbit holes that were way more interesting than I expected: - Left clicks turning into right clicks. Posting ⌃Tab via CGEvent leaks the control flag into macOS's combined-session modifier state. The next synthetic mouse click inherits ctrl, and on macOS ctrl+click == right-click. Fix: explicitly reset flags = [] on mouse events, let keyboard events keep inheriting (otherwise you break system shortcuts). - L1+R1 chord for the keyboard, with a 150ms window. Quick-tapped shoulders must still fire their normal action; the chord only wins if both arrive inside the window. Deferred-DispatchWorkItem + cancel-on-opposite-arrival. - Haptics that actually feel like a mechanical click = a sharp transient layered over a 40ms continuous tail. One event alone feels like a flat buzz. Two layered events feel like a keycap. Honest disclosure: a lot of this was vibe-coded with Claude. I drove, Claude did plenty of the typing. I'm calling that out because the interesting thing isn't that I hand-wrote every line — it's that the debugging stories above (the PS button, the modifier leak, the chord window timing) are all real problems we actually hit, diagnosed from logs, and fixed. The AI was a good typist; the system design, the "wait, why does this work in Chromium but not us", the hypothesis-forming — still the work. Works on macOS 14+, Liquid Glass UI on Tahoe, Swift Package Manager, no dependencies. MIT. Repo + full bindings + architecture notes: https://github.com/henit-chobisa/macpad