More of a text snippet than a tutorial, this is how it's possible to call a function when the game loses focus.
In this example we have put the callback function in a custom APlayerController subclass, but it could be just about anywhere.
Also it might be worth wrapping this feature in a UUserGameSetting property so players can disable it if they don't want it.
First we need to add Slate to our MyProject.Build.cs file:
MyProject.Build.cs
public class MyProject : ModuleRules
{
public MyProject(ReadOnlyTargetRules Target) : base(Target)
{
PCHUsage = PCHUsageMode.UseExplicitOrSharedPCHs;
PublicDependencyModuleNames.AddRange(new string[] {
"Core",
"CoreUObject",
"Engine",
"InputCore",
"Slate" // Add this!
});
PrivateDependencyModuleNames.AddRange(new string[] { });
}
}
Next, we need to add to our player controller in both the .h and the .cpp:
BUIPlayerController.h
// Fill out your copyright notice in the Description page of Project Settings.
#pragma once
#include "CoreMinimal.h"
#include "BUIPlayerController.generated.h"
UCLASS()
class ABUIPlayerController : public APlayerController
{
GENERATED_BODY()
protected:
virtual void BeginPlay() override;
void OnWindowFocusChanged( bool bIsFocused );
};
BUIPlayerController.cpp
#include "BUIPlayerController.h"
#include "Framework/Application/SlateApplication.h"
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
}
