From 00d93cee8305ee5d4bfc094926a5f446423ab9cf Mon Sep 17 00:00:00 2001
From: Moth Doctor <krzysiek.justynski@gmail.com>
Date: Mon, 23 Aug 2021 23:50:20 +0200
Subject: [PATCH] using Viewport Stats Subsystem to display permanent error
 messages

---
 Source/Flow/Private/Nodes/FlowNode.cpp | 34 ++++++++++++++++++++------
 Source/Flow/Public/FlowTypes.h         |  7 ++++++
 Source/Flow/Public/Nodes/FlowNode.h    |  2 +-
 3 files changed, 35 insertions(+), 8 deletions(-)

diff --git a/Source/Flow/Private/Nodes/FlowNode.cpp b/Source/Flow/Private/Nodes/FlowNode.cpp
index 48353f6b..eb5ee2f5 100644
--- a/Source/Flow/Private/Nodes/FlowNode.cpp
+++ b/Source/Flow/Private/Nodes/FlowNode.cpp
@@ -6,6 +6,7 @@
 #include "FlowTypes.h"
 
 #include "Engine/Engine.h"
+#include "Engine/ViewportStatsSubsystem.h"
 #include "Engine/World.h"
 #include "Misc/App.h"
 #include "Misc/Paths.h"
@@ -15,10 +16,10 @@
 FFlowPin UFlowNode::DefaultInputPin(TEXT("In"));
 FFlowPin UFlowNode::DefaultOutputPin(TEXT("Out"));
 
-FString UFlowNode::MissingIdentityTag = TEXT("Missing Identity Tag!");
-FString UFlowNode::MissingNotifyTag = TEXT("Missing Notify Tag!");
-FString UFlowNode::MissingClass = TEXT("Missing class!");
-FString UFlowNode::NoActorsFound = TEXT("No actors found!");
+FString UFlowNode::MissingIdentityTag = TEXT("Missing Identity Tag");
+FString UFlowNode::MissingNotifyTag = TEXT("Missing Notify Tag");
+FString UFlowNode::MissingClass = TEXT("Missing class");
+FString UFlowNode::NoActorsFound = TEXT("No actors found");
 
 UFlowNode::UFlowNode(const FObjectInitializer& ObjectInitializer)
 	: Super(ObjectInitializer)
@@ -356,7 +357,7 @@ void UFlowNode::TriggerOutput(const FName& PinName, const bool bFinish /*= false
 	{
 		Finish();
 	}
-	
+
 #if !UE_BUILD_SHIPPING
 	if (OutputPins.Contains(PinName))
 	{
@@ -551,12 +552,31 @@ FString UFlowNode::GetProgressAsString(float Value)
 	return TempString;
 }
 
-void UFlowNode::LogError(FString Message) const
+void UFlowNode::LogError(FString Message, const EFlowOnScreenMessageType OnScreenMessageType) const
 {
 	const FString TemplatePath = GetFlowAsset()->TemplateAsset->GetPathName();
 	Message += TEXT(" in node ") + GetName() + TEXT(", asset ") + FPaths::GetPath(TemplatePath) + TEXT("/") + FPaths::GetBaseFilename(TemplatePath);
 
-	GEngine->AddOnScreenDebugMessage(-1, 2.0f, FColor::Red, Message);
+	if (OnScreenMessageType == EFlowOnScreenMessageType::Permanent)
+	{
+		if (GetWorld())
+		{
+			if (UViewportStatsSubsystem* StatsSubsystem = GetWorld()->GetSubsystem<UViewportStatsSubsystem>())
+			{
+				StatsSubsystem->AddDisplayDelegate([this, Message](FText& OutText, FLinearColor& OutColor)
+				{
+					OutText = FText::FromString(Message);
+					OutColor = FLinearColor::Red;
+					return !IsPendingKill() && ActivationState != EFlowNodeState::NeverActivated;
+				});
+			}
+		}
+	}
+	else
+	{
+		GEngine->AddOnScreenDebugMessage(-1, 2.0f, FColor::Red, Message);
+	}
+
 	UE_LOG(LogFlow, Error, TEXT("%s"), *Message);
 }
 
diff --git a/Source/Flow/Public/FlowTypes.h b/Source/Flow/Public/FlowTypes.h
index b1a6b390..38344448 100644
--- a/Source/Flow/Public/FlowTypes.h
+++ b/Source/Flow/Public/FlowTypes.h
@@ -41,3 +41,10 @@ enum class EFlowNetMode : uint8
 	ServerOnly			UMETA(ToolTip = "Executed on the server"),
 	SinglePlayerOnly	UMETA(ToolTip = "Executed only in the single player, not available in multiplayer.")
 };
+
+UENUM(BlueprintType)
+enum class EFlowOnScreenMessageType : uint8
+{
+	Temporary,
+	Permanent
+};
diff --git a/Source/Flow/Public/Nodes/FlowNode.h b/Source/Flow/Public/Nodes/FlowNode.h
index 66103f64..300c4874 100644
--- a/Source/Flow/Public/Nodes/FlowNode.h
+++ b/Source/Flow/Public/Nodes/FlowNode.h
@@ -331,7 +331,7 @@ class FLOW_API UFlowNode : public UObject, public IVisualLoggerDebugSnapshotInte
 	static FString GetProgressAsString(float Value);
 
 	UFUNCTION(BlueprintCallable, Category = "FlowNode")
-	void LogError(FString Message) const;
+	void LogError(FString Message, const EFlowOnScreenMessageType OnScreenMessageType = EFlowOnScreenMessageType::Permanent) const;
 
 	UFUNCTION(BlueprintCallable, Category = "FlowNode")
 	void SaveInstance(FFlowNodeSaveData& NodeRecord);