Class InputActionTrace

Records the triggering of actions into a sequence of events that can be replayed at will.

Inheritance
Object
InputActionTrace
Namespace: UnityEngine.InputSystem.Utilities
Syntax
public sealed class InputActionTrace : IEnumerable<InputActionTrace.ActionEventPtr>, IEnumerable, IDisposable
Remarks

This is an alternate way to the callback-based responses (such as performed) of InputAction. Instead of executing response code right away whenever an action triggers, an RecordAction(InputAction.CallbackContext) which can then be queried on demand.

The recorded data will stay valid even if the bindings on the actions are changed (e.g. by enabling a different set of bindings through altering bindingMask or devices or when modifying the paths of bindings altogether). Note, however, that when this happens, a trace will have to make a private copy of the data that stores the binding resolution state. This means that there can be GC allocation spike when reconfiguring actions that have recorded data in traces.

var trace = new InputActionTrace();

// Subscribe trace to single action.
// (Use UnsubscribeFrom to unsubscribe)
trace.SubscribeTo(myAction);

// Subscribe trace to entire action map.
// (Use UnsubscribeFrom to unsubscribe)
trace.SubscribeTo(myActionMap);

// Subscribe trace to all actions in the system.
trace.SubscribeToAll();

// Record a single triggering of an action.
myAction.performed +=
    ctx =>
    {
        if (ctx.ReadValue<float>() > 0.5f)
            trace.RecordAction(ctx);
    };

// Output trace to console.
Debug.Log(string.Join(",\n", trace));

// Walk through all recorded actions and then clear trace.
foreach (var record in trace)
{
    Debug.Log($"{record.action} was {record.phase} by control {record.control} at {record.time}");

    // To read out the value, you either have to know the value type or read the
    // value out as a generic byte buffer. Here we assume that the value type is
    // float.

    Debug.Log("Value: " + record.ReadValue<float>());

    // An alternative is read the value as an object. In this case, you don't have
    // to know the value type but there will be a boxed object allocation.
    Debug.Log("Value: " + record.ReadValueAsObject());
}
trace.Clear();

// Unsubscribe trace from everything.
trace.UnsubscribeFromAll();

// Release memory held by trace.
trace.Dispose();

Constructors

InputActionTrace()

Constructs a new default initialized InputActionTrace.

Declaration
public InputActionTrace()
Remarks

When you use this constructor, the new InputActionTrace object does not start recording any actions. To record actions, you must explicitly set them up after creating the object. Alternatively, you can use one of the other constructor overloads which begin recording actions immediately.

See Also

InputActionTrace(InputAction)

Constructs a new InputActionTrace that records action.

Declaration
public InputActionTrace(InputAction action)
Parameters
Type Name Description
InputAction action

The action to be recorded.
Exceptions
Type Condition
ArgumentNullException

Thrown if action is null.

InputActionTrace(InputActionMap)

Constructs a new InputActionTrace that records all actions in actionMap.

Declaration
public InputActionTrace(InputActionMap actionMap)
Parameters
Type Name Description
InputActionMap actionMap

The action-map containing actions to be recorded.
Exceptions
Type Condition
ArgumentNullException

Thrown if action is null.

Properties

buffer

Directly access the underlying raw memory queue.

Declaration
public InputEventBuffer buffer { get; }
Property Value
Type Description
InputEventBuffer

count

Returns the number of events in the associated event buffer.

Declaration
public int count { get; }
Property Value
Type Description
Int32

Methods

Clear()

Clears all recorded data.

Declaration
public void Clear()
Remarks

Note: This method does not unsubscribe any actions that the instance is listening to, so after clearing the recorded data, new input on those subscribed actions will continue to be recorded.

Dispose()

Declaration
public void Dispose()
Implements

Finalize()

Declaration
protected void Finalize()

GetEnumerator()

Returns an enumerator that enumerates all action events recorded for this instance.

Declaration
public IEnumerator<InputActionTrace.ActionEventPtr> GetEnumerator()
Returns
Type Description
IEnumerator<InputActionTrace.ActionEventPtr>

Enumerator instance, never null.
Implements
See Also

RecordAction(InputAction.CallbackContext)

Record the triggering of an action as an InputActionTrace.ActionEventPtr.

Declaration
public void RecordAction(InputAction.CallbackContext context)
Parameters
Type Name Description
InputAction.CallbackContext context

SubscribeTo(InputAction)

Subscribes to action.

Declaration
public void SubscribeTo(InputAction action)
Parameters
Type Name Description
InputAction action

The action to be recorded.
Remarks

Note: This method does not prevent you from subscribing to the same action multiple times. If you subscribe to the same action multiple times, your event buffer will contain duplicate entries.

Exceptions
Type Condition
ArgumentNullException

If action is null.
See Also

SubscribeTo(InputActionMap)

Subscribes to all actions contained within actionMap.

Declaration
public void SubscribeTo(InputActionMap actionMap)
Parameters
Type Name Description
InputActionMap actionMap

The action-map containing all actions to be recorded.
Remarks

Note: This method does not prevent you from subscribing to the same action multiple times. If you subscribe to the same action multiple times, your event buffer will contain duplicate entries.

Exceptions
Type Condition
ArgumentNullException

Thrown if actionMap is null.
See Also

SubscribeToAll()

Record any action getting triggered anywhere.

Declaration
public void SubscribeToAll()
Remarks

This does not require the trace to actually hook into every single action or action map in the system. Instead, the trace will listen to onActionChange and automatically record every triggered action.

See Also

ToString()

Declaration
public override string ToString()
Returns
Type Description
String
Overrides

UnsubscribeFrom(InputAction)

Unsubscribes from an action, if that action was previously subscribed to.

Declaration
public void UnsubscribeFrom(InputAction action)
Parameters
Type Name Description
InputAction action

The action to unsubscribe from.
Remarks

Note: This method has no side effects if you attempt to unsubscribe from an action that you have not previously subscribed to.

Exceptions
Type Condition
ArgumentNullException

Thrown if action is null.
See Also

UnsubscribeFrom(InputActionMap)

Unsubscribes from all actions included in actionMap.

Declaration
public void UnsubscribeFrom(InputActionMap actionMap)
Parameters
Type Name Description
InputActionMap actionMap

The action-map containing actions to unsubscribe from.
Remarks

Note: This method has no side effects if you attempt to unsubscribe from an action-map that you have not previously subscribed to.

Exceptions
Type Condition
ArgumentNullException

Thrown if actionMap is null.
See Also

UnsubscribeFromAll()

Unsubscribes from all actions currently being recorded.

Declaration
public void UnsubscribeFromAll()
See Also

Explicit Interface Implementations

IEnumerable.GetEnumerator()

Declaration
IEnumerator IEnumerable.GetEnumerator()
Returns
Type Description
IEnumerator
Implements

See Also