Application lost focus event

Development Programming & Scripting
1

Hi,

I’m searching to set a pause menu and pause the game when lost the focus of the application but I don’t find a lost focus event.

Is it possible to know when the window lost focus ? How ?

Thanks

2

I think you are looking for:

UGameViewportClient::LostFocus

You can derive from this class and make your own functionality, of course it needs to be done in c++.

3

The engine must be changed and recompiled or a way exists to add an event without doing that ?

4

Nope, only your c++ game module.

5

I added c++ code like that :

#pragma once

#include "Engine/GameViewportClient.h"
#include "MyGameViewportClient.generated.h"

DECLARE_DYNAMIC_MULTICAST_DELEGATE(FLostFocusSignature);

/**
 * UMyGameViewportClient class.
 */
UCLASS()
class GAME_API UMyGameViewportClient : public UGameViewportClient
{
  GENERATED_BODY()

public:

  // Lost focus event.
  UPROPERTY(BlueprintAssignable, Category="LostFocus")
  FLostFocusSignature OnLostFocus;

  // Override lost focus function.
  virtual void LostFocus(FViewport* Viewport) override;
};

#include "Game.h"
#include "MyGameViewportClient.h"

void UMyGameViewportClient::LostFocus(FViewport* Viewport)
{
  UGameViewportClient::LostFocus(Viewport);
  OnLostFocus.Broadcast();
}

The problem is I don’t see the event in my game mode blueprint to call a pause game and show a pause menu, and I don’t find a node in blueprint to get the game viewport (maybe not possible). Is it possible to have a global event spawned to have access in game mode blueprint ?

6

Push your event throught gameinstance and the event will be globally, you can obtain game instance from BP. And you can obtain your game instance from UMyGameViewportClient.

7

Ok, that works but sometimes the event is not sent, I don’t know why, actually not 100% safe to use.

#pragma once

#include "Engine/GameInstance.h"
#include "LostFocusGameInstance.generated.h"

DECLARE_DYNAMIC_MULTICAST_DELEGATE(FLostFocusSignature);

/**
 * ULostFocusGameInstance class.
 */
UCLASS()
class GAME_API ULostFocusGameInstance : public UGameInstance
{
	GENERATED_BODY()

public:

	// Lost focus event.
	UPROPERTY(BlueprintAssignable, Category="LostFocus")
	FLostFocusSignature OnLostFocus;
};

#pragma once

#include "Engine/GameViewportClient.h"
#include "MyGameViewportClient.generated.h"

/**
 * UMyGameViewportClient class.
 */
UCLASS()
class GAME_API UMyGameViewportClient : public UGameViewportClient
{
	GENERATED_BODY()

public:

	// Override lost focus function.
	virtual void LostFocus(FViewport* Viewport) override;
};

#include "Game.h"
#include "MyGameViewportClient.h"
#include "LostFocusGameInstance.h"

void UMyGameViewportClient::LostFocus(FViewport* Viewport)
{
	UGameViewportClient::LostFocus(Viewport);
	static_cast<ULostFocusGameInstance*>(GameInstance)->OnLostFocus.Broadcast();
}
8

Would be so nice to get an event like this - in blueprint…

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9

if someone having issues with UGameViewportClient::LostFocus
then another possible solution is:

// the following code is qouted from: https://benui.ca/unreal/window-focus-change/
void ABUIPlayerController::BeginPlay()
{
	FSlateApplication::Get().OnApplicationActivationStateChanged()
		.AddUObject( this, &ABUIPlayerController::OnWindowFocusChanged );
}

void ABUIPlayerController::OnWindowFocusChanged( bool bIsFocused )
{
// Don't pause in the editor, it's annoying
#if !WITH_EDITOR
	if ( bIsFocused )
	{
		// Unlimit game FPS
		GEngine->SetMaxFPS( 0 );

		// Unpause the game
		// MyHUD->SetPause( false );
	}
	else
	{
		// Reduce FPS to max 10 while in the background
		GEngine->SetMaxFPS( 10.0f );

		// Pause the game, using your "show pause menu" function
		// MyHUD->SetPause( true );
	}
#endif
}

thanks to Ben @ Pause Game When Window Loses Focus · ben🌱ui

4 Likes