CODEWITHSUNDEEP
swiftmacoshidiokit
pfg
pfg

Reputation: 3577

Get a ForceFeedback device in Swift

I can get a hid device like this

import ForceFeedback
import IOKit.hid

private func createDeviceMatchingDictionary( usagePage: Int, usage: Int) -> CFMutableDictionary {
    let dict = [
        kIOHIDDeviceUsageKey: usage,
        kIOHIDDeviceUsagePageKey: usagePage
        ] as NSDictionary

    return dict.mutableCopy() as! NSMutableDictionary;
}

let manager = IOHIDManagerCreate(kCFAllocatorDefault, IOOptionBits(kIOHIDOptionsTypeNone));
let trackpad = createDeviceMatchingDictionary(usagePage: kHIDPage_GenericDesktop, usage: kHIDUsage_GD_Mouse)

IOHIDManagerOpen(manager, IOOptionBits(kIOHIDOptionsTypeNone) )
IOHIDManagerSetDeviceMatching(manager, trackpad)

let devices = IOHIDManagerCopyDevices(manager)

However none of this returns either a io_service_t or a UnsafeMutablePointer<FFDeviceObjectReference> required to use FFCreateDevice()

How do I get a forcefeedback device and use FFCreateEffect on it?

Upvotes: 0

Views: 307

Answers (1)

Ryan H
Ryan H

Reputation: 1746

The idea behind a lot of Objective-C or C style frameworks is that you pass in pointers for the objects you expect to be created by a function, and the functions return codes so that you know if the operation was successful or not.

You can use IOHIDDeviceGetService(device) to get your io_service_t. You can then create an optional object of type FFDeviceObjectReference and pass in its reference to FFCreateDevice. Here's an (untested) example that seems like it should work:

import IOKit.hid
import ForceFeedback

class ForceFeedback {

    public func listen() {

        let hidManager = IOHIDManagerCreate(kCFAllocatorDefault, IOOptionBits(kIOHIDOptionsTypeNone))
        let hidDevices = [
            kIOHIDDeviceUsagePageKey: kHIDPage_GenericDesktop,
            kIOHIDDeviceUsageKey: kHIDUsage_GD_Mouse
        ]

        IOHIDManagerSetDeviceMatching(hidManager, hidDevices as CFDictionary)

        let deviceMatchingCallback: IOHIDDeviceCallback = {context, result, sender, device in

            var ffDevice: FFDeviceObjectReference? = nil
            let result = FFCreateDevice(IOHIDDeviceGetService(device), &ffDevice)
            if result != FF_OK {
                print("could not create force feedback device")
            }

            var ffEffect: FFEffectObjectReference? = nil
            var effectDefinition = FFEFFECT() // You'd create your effect here

            // Pick your UUID and build it here. For example, this is the constant force effect type
            // E559C460-C5CD-11D6-8A1C-00039353BD00
            let constantForce: CFUUID = CFUUIDCreateWithBytes(kCFAllocatorDefault,
                                                              0xE5, 0x59, 0xC4, 0x60, 0xC5, 0xCD, 0x11, 0xD6,
                                                              0x8A, 0x1C, 0x00, 0x03, 0x93, 0x53, 0xBD, 0x00)

            let effectResult = FFDeviceCreateEffect(ffDevice, constantForce, &effectDefinition, &ffEffect)
            if effectResult != FF_OK {
                print("could not create effect")
            }

            // Start and stop your effect
            // Don't forget to clean up your ffDevice and ffEffect when done.
        }

        // bridge your context and send it as a parameter instead of nil if needed
        IOHIDManagerRegisterDeviceMatchingCallback(hidManager, deviceMatchingCallback, nil)

        IOHIDManagerScheduleWithRunLoop(hidManager, CFRunLoopGetCurrent(), CFRunLoopMode.defaultMode.rawValue)
        CFRunLoopRun()
    }

}

Note that I register the HID callback so that the code runs when a device is added.

Upvotes: 1

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