Struct InputEventListener

Wraps around mechanisms for listening in on the InputEvent stream made available through onEvent.

Namespace: UnityEngine.InputSystem.LowLevel
Syntax
public struct InputEventListener : IObservable<InputEventPtr>
Remarks

This struct can be used to add (Addition(InputEventListener, Action<InputEventPtr, InputDevice>)) or remove (Subtraction(InputEventListener, Action<InputEventPtr, InputDevice>)) callbacks directly to/from the event pipeline.

Alternatively, it can be used as an IObservable to Subscribe(IObserver<InputEventPtr>) observers to the event stream. See Observable for extension methods to set up various observer mechanisms.

InputSystem.onEvent
    .ForDevice(Mouse.current)
    .Call(evt =>
        {
            foreach (var control in evt.EnumerateChangedControls())
                Debug.Log($"Control {control} on mouse has changed value");
        });

Methods

Subscribe(IObserver<InputEventPtr>)

Subscribe an observer to the event pump.

Declaration
public IDisposable Subscribe(IObserver<InputEventPtr> observer)
Parameters
Type Name Description
IObserver<InputEventPtr> observer

Observer to be notified for each event.
Returns
Type Description
IDisposable

A handle to dispose of the subscription.
Remarks

The easiest way to subscribe is via the extension methods in Observable. 

// Subscribe.
var subscription = InputSystem.onEvent.Call(e => Debug.Log("Event"));

// Unsubscribe.
subscription.Dispose();

Operators

Addition(InputEventListener, Action<InputEventPtr, InputDevice>)

Add a delegate to be called for each InputEvent that is processed by the Input System.

Declaration
public static InputEventListener operator +(InputEventListener _, Action<InputEventPtr, InputDevice> callback)
Parameters
Type Name Description
InputEventListener _
Action<InputEventPtr, InputDevice> callback

A callback to call for each event.
Returns
Type Description
InputEventListener

The same listener instance.
Remarks
InputSystem.onEvent +=
    (eventPtr, device) =>
    {
        Debug.Log($"Event for {device}");
    };
See Also

Subtraction(InputEventListener, Action<InputEventPtr, InputDevice>)

Remove a delegate from InputEvent.

Declaration
public static InputEventListener operator -(InputEventListener _, Action<InputEventPtr, InputDevice> callback)
Parameters
Type Name Description
InputEventListener _
Action<InputEventPtr, InputDevice> callback

A callback that was previously installed on onEvent.
Returns
Type Description
InputEventListener

The same listener instance.
Remarks
InputSystem.onEvent -= myDelegate;
See Also

See Also