Example of how to use MacBook's or Apple Magic Trackpad not for a positioning of the cursor but for getting an absolute coordinates of touches - i.e. as a joystick.
The project (TrackpadJoystick.swift) is combined with a simple example (ViewController.swift) - sending a coordinates over an UDP socket. See wifi-car for the counterpart.
The idea behind the application is to use a custom view - subclass of NSView - to receive one touch at a time. To emulate a real joystick behavior touches are allowed to begin only from the center of he trackpad - in a circle with stickStartPositionRadius radius. Also, after releasing a finger from the panel the stick is automatically returning to the start position.
Coordinates are retrieving in a real time on every request to the TrackpadJoystick.centeredCoords member.
To prevent distractions in cases when the window is losing focus the app is running itself in a fullscreen mode (use Cmd+Q to exit). Currently, I haven't found a simple way to make an NSView a fully transparent overlay in a fullscreen mode to place other UI elements behind it and not rely on them in the main TrackpadJoystick class. So if you want any additional UI components please put them in this class.
TrackpadJoystick itself has no dependencies although the example has one - it uses IBM-Swift/BlueSocket as a simple socket framework:
- Install IBM-Swift/BlueSocket via Carthage (
carthage update) and embed them in your build target - Turn on network connections (Project settings -> Capabilities -> App Sandbox -> Network)
- Create and configure your desired UI and outlets in the Interface Builder
See (ViewController.swift) to see a concept of how to instantiate and use the joystick. In two words, you need to:
// create one
@IBOutlet weak var trackpadJoystick: TrackpadJoystick!
// retrieve coordinates
let c = trackpadJoystick.centeredCoords
print("x = \(c.x), y = \(c.y)")Centered means that the center of the trackpad is considered an origin point (0.0; 0.0) and the range for both X and Y axes is [-1.0; 1.0]. There are some another initialization and converting methods available through the CenteredCoords interface such as toNormalized(), toScreenCoords().
Check for TODOs all over the code to get the insight of what would be great to do.