Move main window to other display from plugin

Development Programming & Scripting C++
,
1

Hi,
Unreal 5.0.3, Linux.
I’m working on plugin which will detect some OS parameters and modify main app. My HW has 3 displays and we want to choose where to place app by display ID/index.
First attempt ended with

	UGameViewportClient* viewportClient = GEngine->GameViewport;

	if (viewportClient)
	{
		TSharedPtr<SWindow> slateWindow = viewportClient->GetWindow();

		if (slateWindow)
		{
			TSharedPtr<FGenericWindow> nativeWindow = slateWindow->GetNativeWindow();

			FDisplayMetrics DisplayMetrics;
			FSlateApplication::Get().GetDisplayMetrics(DisplayMetrics);
			if (MonitorIndex < 0 || MonitorIndex>=DisplayMetrics.MonitorInfo.Num())
			{
				UE_LOG( LogTemp, Warning, TEXT("=> Incorrect monitor index (%d)"), MonitorIndex);
				return;
			}
	
			const FMonitorInfo & MonitorInfo = DisplayMetrics.MonitorInfo[MonitorIndex];
			nativeWindow->SetWindowMode(EWindowMode::Windowed);
			nativeWindow->MoveWindowTo(MonitorInfo.DisplayRect.Left, MonitorInfo.DisplayRect.Top);
			nativeWindow->SetWindowMode(EWindowMode::WindowedFullscreen);
		}
	}

Without changing window mode Fullscreen->WIndow->Fullscreen this doesn’t move game window where I want it. And some slight flicker is visible. I would like to avoid it.

Second idea is to dynamically change FCommandLine to add WinX and WinY with above acquired positions and let GameEngine create GameWindow already where I want it to be.
But I’m unable to modify FCommandLine (with Get()/Set() or Append()) in a way that it would be visible to GameEngine class.
Is it possible?
I would welcome any tips to solve this problem.

2

Hi Sebastian_Mo,
Years ago (UE4.1) I made some changes to the code to allow me to pass in a window handle (was windows only, but the same concept would work for linux) via the command line and UE would open in that - it was pretty smooth, no flickers or anything - and it wasn’t a lot of code that had to be changed… Maybe this way could work for you too, create your window first then open UE into it.

3

Because we already had some engine patches - I simply added my above mentioned code piece to UGameEngine::CreateGameWindow() where WinX/WinY is processed.
And I achieved my desired result.

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