monitor cocoa trackpad events

monitor.swift

import Foundation
import ApplicationServices

let mask = (
    (1 << CGEventType.leftMouseDown.rawValue)  |
    (1 << CGEventType.leftMouseUp.rawValue)    |
    (1 << CGEventType.mouseMoved.rawValue)     |
    (1 << CGEventType.otherMouseDown.rawValue) |
    (1 << CGEventType.otherMouseUp.rawValue)
)

func describe(_ event: CGEvent) -> String {
    let type = event.type
    let loc = event.location
    let clickState = event.getIntegerValueField(.mouseEventClickState) // 1=single, 2=double
    let flags = event.flags.rawValue
    return "type=\(type) click=\(clickState) x=\(Int(loc.x)) y=\(Int(loc.y)) flags=0x\(String(flags, radix: 16))"
}

let tapCallback: CGEventTapCallBack = { _, type, event, _ in
    // Only print mouse down/up; add others if you like
    switch type {
    case .leftMouseDown, .leftMouseUp, .otherMouseDown, .otherMouseUp:
        print(describe(event))
    default:
        // print("Unhandled event type: \(type)")
        break
    }
    return Unmanaged.passRetained(event)
}

guard let tap = CGEvent.tapCreate(
    tap: .cgSessionEventTap,
    place: .headInsertEventTap,
    options: .defaultTap,
    eventsOfInterest: CGEventMask(mask),
    callback: tapCallback,
    userInfo: nil
) else {
    fputs("ERROR: Could not create event tap (add Input Monitoring permission?)\n", stderr)
    exit(1)
}

let runLoopSource = CFMachPortCreateRunLoopSource(kCFAllocatorDefault, tap, 0)
CFRunLoopAddSource(CFRunLoopGetCurrent(), runLoopSource, .commonModes)
CGEvent.tapEnable(tap: tap, enable: true)
print("Listening…  (grant Terminal ‘Input Monitoring’ in System Settings > Privacy & Security)")
CFRunLoopRun()