SetFocus not working when called from Construct

[Owl_Theory]

I’m using UE4.27.

When my widget is constructed, I want to set the focus to one of the buttons. However, it seems that “SetFocus()” doesn’t actually focus on the widget when called on Construct or OnInitialize. I need to wait at least a frame (sometimes even 0.2 seconds) and then call SetFocus() before it actually focuses. This occurs in Blueprints and C++.

Upon further inspection, in UWidget::SetUserFocus(), note line 564-565:

TSharedPtr SafeWidget = GetCachedWidget();
if ( SafeWidget.IsValid() )

If SetFocus() is not delayed, IsValid() will return false. If it is delayed, then it returns true.

Is there a safe way of focusing during construction? I experimented with calling SetFocus() in a variety of virtual functions, but no success.

[Tuerer]

Yes. this is an issue, and in c++ it will even crash the engine sometimes.
I ended up calling SetFocus() by the class that creates the widget, and it seems to work fine.

[Roy_Wierer.Seda145]

I love how it silently fails in a void returning method. It’s one of these things that will make you have to debug old code when it “randomly” starts to misbehave later in the project.

[Roy_Wierer.Seda145]

According to this post:

UMG - NativeConstruct + SetUserFocus

Hello, SetUserFocus calls are ignored when trying to focus a Widget in NativeConstruct() in code (or OnConstruct in Blueprint). If you add any amount of delay to the call, the call will succeed, though this isn’t a good solution. Setting focus in NativeConstruct() is a common operation since that’s where screens initialize. One thing to note is that setting focus through setting the input mode always works, though this is also not a great solution since we might not always want to reset the inp…

Something like this would work:

void USlateUtils::SetFocusOrDelayedFocus(APlayerController* InPlayerController, UWidget* InWidget) {
	if (!IsValid(InPlayerController) || !IsValid(InWidget)) {
		return;
	}

	InWidget->SetUserFocus(InPlayerController);
	if (!InWidget->HasUserFocus(InPlayerController)) {
		FLocalPlayerContext Context(InPlayerController);
		if (ULocalPlayer* LocalPlayer = Context.GetLocalPlayer()) {
			TOptional<int32> UserIndex = FSlateApplication::Get().GetUserIndexForController(LocalPlayer->GetControllerId());
			if (UserIndex.IsSet()) {
				LocalPlayer->GetSlateOperations().SetUserFocus(InWidget->GetCachedWidget().ToSharedRef());
			}
		}
	}
}

That is bloody ugly and messes with the next frame. Something tells me we can’t we just enforce the “SafeWidget” creation at that point without messing up something else. Thoughts?

[lehuan5062 (Huân Lê-Vương)]

Just make sure we set input mode before creating the UI:

UWidgetBlueprintLibrary::SetInputMode_GameAndUIEx(PlayerController);
PauseMenu = CreateWidget<UUserWidget>(PlayerController, PauseMenuClass.LoadSynchronous());
PauseMenu->AddToViewport();

That make SetFocus works from construct event for me in the blueprint.