Apply color to nested array property rows. BlueprintCallable / Python Version

USomeBPLib.cpp

void RecursivelyFindChildrenWidgetsOfType(TSharedPtr<SWidget> Widget, FString WidgetType, TArray<TSharedPtr<SWidget>>& OutFindedChildrenWidgets)
{
	if (!Widget.IsValid())
	{
		return;
	}

	FChildren* Children = Widget->GetChildren();
	if (Children)
	{
		for (int32 i = 0; i < Children->Num(); i++)
		{
			TSharedPtr<SWidget> Child = Children->GetChildAt(i);
			if (Child.IsValid())
			{
				if (Child->GetTypeAsString().Equals(WidgetType))
				{
					OutFindedChildrenWidgets.AddUnique(Child);
				}
				RecursivelyFindChildrenWidgetsOfType(Child, WidgetType, OutFindedChildrenWidgets);
			}
		}
	}
}

int32 GetGenBySize(TSharedPtr<SWidget> Widget) 
{
	FVector2D Size = Widget->GetDesiredSize();
	return FMath::RoundToInt(Size.X/16);    
}

void USomeBPLib::ApplyRainbowColor(float ColorMultiplier /*default = 1*/)
{
	// The code below is a quick and **dirty** snippet, for demonstrating how to find private widgets and apply colors by the nested struct's indent
  // without change engine code.
  // Call this function from BP or python, will apply the rainbow colors to current Details Window
  // Only the generated row's color will be changed, once the DetailRow regenerated(Expand/Collapse), the color will dispared. So we need cache the widgets, and apply color when the Widget changed. 
  // call as py: unreal.SomeBPLib.apply_rainbow_color()
  // The elegant and better way is change the Engine code, or implement a custom details panel
  
  
	TSharedPtr<SWidget> DetailsView;

	// 1. find the main window
	TSharedPtr<SWindow> MainWindow = GetMainWindow();
	if (MainWindow == nullptr)
	{
		UE_LOG(PythonTA, Log, TEXT("Can't find Main Window"));
		return;
	}

	// 2. find the detail window
	TArray<TSharedPtr<SWidget>> SActorDetailsWidgets;
	RecursivelyFindChildrenWidgetsOfType(MainWindow, "SActorDetails", SActorDetailsWidgets);
	TSharedPtr<SWidget> ActorDetail;

	TArray<TSharedPtr<SWidget>> SDetailsViewWidgets;
	if (SActorDetailsWidgets.Num() > 0) 
	{
		ActorDetail = SActorDetailsWidgets[0];	// assume only one actor Detail in window

		RecursivelyFindChildrenWidgetsOfType(ActorDetail, "SDetailsView", SDetailsViewWidgets);
		if (SDetailsViewWidgets.Num() > 0) {
			UE_LOG(PythonTA, Log, TEXT("Found SDetailsView"));
			DetailsView = SDetailsViewWidgets[0];
		}
	}

	TArray<FLinearColor> RainbowColors{  FLinearColor::Red, FLinearColor(1, 0.5, 0) 
								, FLinearColor::Yellow , FLinearColor::Green 
								, FLinearColor(0, 0.5, 1), FLinearColor(0.3, 0.3, 1) /*avoid too dark blue*/
								, FLinearColor(1, 0, 1) };

	if (DetailsView.IsValid())
	{
		FString WidgetTypeName = DetailsView->GetType().ToString();

		// 3. find the Row Indent 
		TArray<TSharedPtr<SWidget>> OutFindedChildrenWidgets;
		RecursivelyFindChildrenWidgetsOfType(DetailsView, "SDetailRowIndent", OutFindedChildrenWidgets);

		for (auto W : OutFindedChildrenWidgets)
		{
			TSharedPtr<SCompoundWidget> AsTypeWidget = StaticCastSharedPtr<SCompoundWidget>(W);
			
			// 4. Get the Row of the RowIndent, and apply colors
			TSharedPtr<SWidget> Row = GetParentByType(W, "SDetailSingleItemRow");
			if (Row == nullptr)
				continue;

			int32 Gen = GetGenBySize(W);

			if (Row != nullptr) {
				
				if (ColorMultiplier == 0) {
					StaticCastSharedPtr<SCompoundWidget>(Row)->SetColorAndOpacity(FLinearColor::White);
				}
				else {
					if (Gen % 8 != 0)
						StaticCastSharedPtr<SCompoundWidget>(Row)->SetColorAndOpacity(RainbowColors[Gen % 8 - 1] * ColorMultiplier);
				}
			}
		}
	}
}

TSharedPtr<SWindow> USomeBPLib::GetMainWindow() 
{
	TSharedPtr<SWindow> MainWindow = nullptr;

	TArray<TSharedRef<SWindow>> Windows = FSlateApplication::Get().GetTopLevelWindows();

	int32 MatchedCount = 0;
	for (auto Window : Windows)
	{
		UE_LOG(PythonTA, Log, TEXT("Window: %s"), *Window->GetTitle().ToString());
		
		FString Title = Window->GetTitle().ToString();
    
		if (Title.Find(TEXT(" - Unreal Editor")) != -1) // there should be a better way of get the main window.
		{
			MainWindow = Window;
			MatchedCount += 1;
		}
	}

	if (MatchedCount > 1) 
	{
		UE_LOG(PythonTA, Error, TEXT("Multi Main-Window was founded. %d"), MatchedCount);
	}
	return MainWindow;
}

USomeBPLib.h

...

UCLASS()
class USomeBPLib : public UBlueprintFunctionLibrary
{
	GENERATED_BODY()

	UFUNCTION(BlueprintCallable, meta = (Keywords = "Python Editor"), Category = "PythonEditor")
	static void ApplyRainbowColor(float ColorMultiplier=1);
  
  static TSharedPtr<SWindow>  GetMainWindow();
}