CODEWITHSUNDEEP
c++event-handlingunreal-engine4
Avengar
Avengar

Reputation: 89

Event dispatcher calling code function

I have a question about event dispatchers. I've created dispatcher in my code like this:

DECLARE_DYNAMIC_MULTICAST_DELEGATE_OneParam(FSoundPausedDelegate, bool, isSoundPaused);

UPROPERTY(BlueprintAssignable)
        FSoundPausedDelegate AudioPause;

This works perfectly fine in blueprints. However I don't really know, how can i make it to call function in code?

I guess it's going to be something with:

AudioPause.AddDynamic(this, &UAudioController::OnDelegateBroadcast);

What shall I bind it to? This is meant to broadcast value every time i pause/unpause my audio in blueprint and then execute more code logic depending on broadcasted value.

This is how my function looks like:

void UAudioController::OnDelegateBroadcast(bool SoundPaused)
{
    if (SoundPaused == true)
    {
        SoundPause = true;
        GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Red, TEXT("True"));
    }
    else
    {
        SoundPause = false;
        GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Red, TEXT("False"));
    }
}

Upvotes: 4

Views: 4678

Answers (2)

JKovalsky
JKovalsky

Reputation: 348

This is meant to broadcast value every time i pause/unpause my audio in blueprint and then execute more code logic depending on broadcasted value.

So I assume you try to:

  1. Inform other objects in game, that audio playback state is changed
  2. Provide C++ and Blueprint implementation for playback change in your audio controller

My proposition is to create inner UAudioController implementation of playback change using BlueprintNativeEvent. Base C++ implementation will use your dispatcher to propagate notification to other game objects.

This is class .h file in short.

    
    DECLARE_DYNAMIC_MULTICAST_DELEGATE_OneParam( FSoundPausedDelegate, bool, isSoundPaused );

    ...

    //Convenient Play/Pause function for blueprint
    UFUNCTION( BlueprintCallable, Category="Example" )
    void    Play();

    UFUNCTION( BlueprintCallable, Category="Example" )
    void    Pause();

    //Implementation for pause state change
    UFUNCTION( BlueprintNativeEvent, Category="Example" )
    void    OnSoundPaused( bool paused );
    void    OnSoundPaused_Implementation( bool paused );

    ...

    //event dispatcher
    UPROPERTY( VisibleAnywhere, BlueprintAssignable )
    FSoundPausedDelegate AudioPauseEvent;

Convenient functions simply call implementation:

void    UAudioController::Play()
{
    OnSoundPaused( false );
}


void    UAudioController::Pause()
{
    OnSoundPaused( true );
}

Implementation is defined first as C++ code, which also fire AudioPauseEvent with Broadcast function:

void    UAudioController::OnSoundPaused_Implementation( bool paused )
{
    if( paused == true )
    {
        SoundPause = true;
        GEngine->AddOnScreenDebugMessage( -1, 5.f, FColor::Red, TEXT( "True" ) );
        // more logic...
    }
    else
    {
        SoundPause = false;
        GEngine->AddOnScreenDebugMessage( -1, 5.f, FColor::Red, TEXT( "False" ) );
        // more logic...
    }

    AudioPauseEvent.Broadcast( SoundPause );
}

Implementation of OnSoundPaused could be then overridden in Bluepint derived from UAudioController:

enter image description here

Having AudioPauseEvent let you to notify other game objects. Example below show how to subscribe for pause change in level blueprint:

enter image description here

You could also subscribe other objects (for example UAudioListener) from C++ for this event: 

void UAudioListener::StartListeningForAudioPause()
{
    // UAudioListener::OnAudioPause should be UFUNCTION
    AudioControllerPtr->AudioPauseEvent.AddDynamic( this, &UAudioListener::OnAudioPause );
}

Upvotes: 2

JonS
JonS

Reputation: 421

You want another UPROPERTY called BlueprintImplementableEvent, this lets you define a code function that can be overridden by Blueprint. See https://answers.unrealengine.com/questions/38960/blueprintimplementableevent-in-level-blueprint.html

Upvotes: 0

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