NavigationEventInput

Artifact: androidx.navigationevent:navigationevent

Kotlin |Java

Cmn
```
abstract class NavigationEventInput
```

Known direct subclasses

DirectNavigationEventInput, OnBackInvokedInput

`DirectNavigationEventInput`	An input that can send events to a `NavigationEventDispatcher`.
`OnBackInvokedInput`	Provides input to a `NavigationEventDispatcher` by registering an `OnBackInvokedCallback` to the passed in `onBackInvokedDispatcher`.

Known indirect subclasses

OnBackInvokedDefaultInput, OnBackInvokedOverlayInput

`OnBackInvokedDefaultInput`	Provides input to a `NavigationEventDispatcher` by registering an `OnBackInvokedCallback` with the `OnBackInvokedDispatcher.PRIORITY_DEFAULT` priority to `onBackInvokedDispatcher`.
`OnBackInvokedOverlayInput`	Provides input to a `NavigationEventDispatcher` by registering an `OnBackInvokedCallback` with the `OnBackInvokedDispatcher.PRIORITY_OVERLAY` priority to `onBackInvokedDispatcher`.

An abstract class for components that generate and dispatch navigation events.

This class acts as the "input" side of the navigation system, translating platform-specific events (like system back gestures or button clicks) into standardized events that can be sent to a NavigationEventDispatcher.

Subclasses are responsible for implementing the logic that sources these events and calling the dispatchOn... methods (e.g., dispatchOnBackStarted) to propagate them through the system.

An input must be registered with a NavigationEventDispatcher using NavigationEventDispatcher.addInput to function.

See also
`NavigationEventDispatcher`
`NavigationEventHandler`

Summary

Public constructors
`NavigationEventInput()`	Cmn

Protected functions
`Unit`	`@MainThread dispatchOnBackCancelled()` Notifies the dispatcher that the ongoing `TRANSITIONING_BACK` navigation gesture has been cancelled.	Cmn
`Unit`	`@MainThread dispatchOnBackCompleted()` Notifies the dispatcher that the ongoing `TRANSITIONING_BACK` navigation gesture has completed.	Cmn
`Unit`	`@MainThread dispatchOnBackProgressed(event: NavigationEvent)` Notifies the dispatcher that an ongoing `TRANSITIONING_BACK` navigation gesture has progressed.	Cmn
`Unit`	`@MainThread dispatchOnBackStarted(event: NavigationEvent)` Notifies the dispatcher that a `TRANSITIONING_BACK` navigation gesture has started.	Cmn
`Unit`	`@MainThread dispatchOnForwardCancelled()` Notifies the dispatcher that the ongoing `TRANSITIONING_FORWARD` navigation gesture has been cancelled.	Cmn
`Unit`	`@MainThread dispatchOnForwardCompleted()` Notifies the dispatcher that the ongoing `TRANSITIONING_FORWARD` navigation gesture has completed.	Cmn
`Unit`	`@MainThread dispatchOnForwardProgressed(event: NavigationEvent)` Notifies the dispatcher that an ongoing `TRANSITIONING_FORWARD` navigation gesture has progressed.	Cmn
`Unit`	`@MainThread dispatchOnForwardStarted(event: NavigationEvent)` Notifies the dispatcher that a `TRANSITIONING_FORWARD` navigation gesture has started.	Cmn
`open Unit`	`@MainThread @EmptySuper onAdded(dispatcher: NavigationEventDispatcher)` Called after this `NavigationEventInput` is added to `dispatcher`.	Cmn
`open Unit`	`@MainThread @EmptySuper onHasEnabledHandlersChanged(hasEnabledHandlers: Boolean)` Called when the enabled state of handlers in the connected `NavigationEventDispatcher` changes.	Cmn
`open Unit`	`@MainThread @EmptySuper onHistoryChanged(history: NavigationEventHistory)` Called when the `NavigationEventHistory` state in the connected `NavigationEventDispatcher` changes.	Cmn
`open Unit`	`@MainThread @EmptySuper onRemoved()` Called after this `NavigationEventInput` is removed from a `NavigationEventDispatcher`.	Cmn

Public constructors

NavigationEventInput

Cmn

Added in 1.0.0-alpha09

NavigationEventInput()

Protected functions

dispatchOnBackCancelled

Cmn

Added in 1.0.0-alpha09

@MainThread
protected fun dispatchOnBackCancelled(): Unit

Notifies the dispatcher that the ongoing TRANSITIONING_BACK navigation gesture has been cancelled.

This is a terminal event. The NavigationEventDispatcher.transitionState will become Idle and ready for a new gesture.

Throws
`kotlin.IllegalStateException`	if this input is not added to a dispatcher.
`kotlin.IllegalStateException`	if this dispatcher is disposed.

dispatchOnBackCompleted

Cmn

Added in 1.0.0-alpha09

@MainThread
protected fun dispatchOnBackCompleted(): Unit

Notifies the dispatcher that the ongoing TRANSITIONING_BACK navigation gesture has completed.

This is a terminal event, signaling that the navigation should be finalized (e.g., popping the back stack). The NavigationEventDispatcher.transitionState will become Idle and ready for a new gesture.

Throws
`kotlin.IllegalStateException`	if this input is not added to a dispatcher.
`kotlin.IllegalStateException`	if this dispatcher is disposed.

dispatchOnBackProgressed

Cmn

Added in 1.0.0-alpha09

@MainThread
protected fun dispatchOnBackProgressed(event: NavigationEvent): Unit

Notifies the dispatcher that an ongoing TRANSITIONING_BACK navigation gesture has progressed.

The NavigationEventDispatcher.transitionState will become InProgress.

Parameters
`event: NavigationEvent`	The `NavigationEvent` describing the progress of the gesture.

Throws
`kotlin.IllegalStateException`	if this input is not added to a dispatcher.
`kotlin.IllegalStateException`	if this dispatcher is disposed.

dispatchOnBackStarted

Cmn

Added in 1.0.0-alpha09

@MainThread
protected fun dispatchOnBackStarted(event: NavigationEvent): Unit

Notifies the dispatcher that a TRANSITIONING_BACK navigation gesture has started.

The NavigationEventDispatcher.transitionState will become InProgress.

Parameters
`event: NavigationEvent`	The `NavigationEvent` describing the start of the gesture (e.g., touch position).

Throws
`kotlin.IllegalStateException`	if this input is not added to a dispatcher.
`kotlin.IllegalStateException`	if this dispatcher is disposed.

dispatchOnForwardCancelled

Cmn

Added in 1.0.0-alpha09

@MainThread
protected fun dispatchOnForwardCancelled(): Unit

Notifies the dispatcher that the ongoing TRANSITIONING_FORWARD navigation gesture has been cancelled.

This is a terminal event. The NavigationEventDispatcher.transitionState will become Idle and ready for a new gesture.

Throws
`kotlin.IllegalStateException`	if this input is not added to a dispatcher.
`kotlin.IllegalStateException`	if this dispatcher is disposed.

dispatchOnForwardCompleted

Cmn

Added in 1.0.0-alpha09

@MainThread
protected fun dispatchOnForwardCompleted(): Unit

Notifies the dispatcher that the ongoing TRANSITIONING_FORWARD navigation gesture has completed.

Throws
`kotlin.IllegalStateException`	if this input is not added to a dispatcher.
`kotlin.IllegalStateException`	if this dispatcher is disposed.

dispatchOnForwardProgressed

Cmn

Added in 1.0.0-alpha09

@MainThread
protected fun dispatchOnForwardProgressed(event: NavigationEvent): Unit

Notifies the dispatcher that an ongoing TRANSITIONING_FORWARD navigation gesture has progressed.

The NavigationEventDispatcher.transitionState will become InProgress.

Parameters
`event: NavigationEvent`	The `NavigationEvent` describing the progress of the gesture.

Throws
`kotlin.IllegalStateException`	if this input is not added to a dispatcher.
`kotlin.IllegalStateException`	if this dispatcher is disposed.

dispatchOnForwardStarted

Cmn

Added in 1.0.0-alpha09

@MainThread
protected fun dispatchOnForwardStarted(event: NavigationEvent): Unit

Notifies the dispatcher that a TRANSITIONING_FORWARD navigation gesture has started.

The NavigationEventDispatcher.transitionState will become InProgress.

Parameters
`event: NavigationEvent`	The `NavigationEvent` describing the start of the gesture (e.g., touch position).

Throws
`kotlin.IllegalStateException`	if this input is not added to a dispatcher.
`kotlin.IllegalStateException`	if this dispatcher is disposed.

onAdded

Cmn

Added in 1.0.0-alpha09

@MainThread
@EmptySuper
protected open fun onAdded(dispatcher: NavigationEventDispatcher): Unit

Called after this NavigationEventInput is added to dispatcher. This can happen when calling NavigationEventDispatcher.addInput. A NavigationEventInput can only be added to one NavigationEventDispatcher at a time.

Parameters
`dispatcher: NavigationEventDispatcher`	The `NavigationEventDispatcher` that this input is now added to.

onHasEnabledHandlersChanged

Cmn

Added in 1.0.0-alpha09

@MainThread
@EmptySuper
protected open fun onHasEnabledHandlersChanged(hasEnabledHandlers: Boolean): Unit

Called when the enabled state of handlers in the connected NavigationEventDispatcher changes.

This allows the input to enable or disable its own event sourcing. For example, a system back gesture input might only register for gestures when hasEnabledHandlers is true.

The exact set of handlers this reflects depends on the Priority this input was registered with.

Parameters
`hasEnabledHandlers: Boolean`	Whether the connected dispatcher has any enabled handlers matching this input's priority scope.

onHistoryChanged

Cmn

Added in 1.0.0-alpha09

@MainThread
@EmptySuper
protected open fun onHistoryChanged(history: NavigationEventHistory): Unit

Called when the NavigationEventHistory state in the connected NavigationEventDispatcher changes.

Parameters
`history: NavigationEventHistory`	The new, immutable snapshot of the navigation history.

onRemoved

Cmn

Added in 1.0.0-alpha09

@MainThread
@EmptySuper
protected open fun onRemoved(): Unit

Called after this NavigationEventInput is removed from a NavigationEventDispatcher. This can happen when calling NavigationEventDispatcher.removeInput or NavigationEventDispatcher.dispose on the containing NavigationEventDispatcher.