ViewportStatsSubsystem.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "Subsystems/WorldSubsystem.h"
#include "Tickable.h"
#include "Stats/Stats.h"
#include "Engine/EngineTypes.h"
 
#include "ViewportStatsSubsystem.generated.h"
 
class UWorld;
class FViewport;
class UCanvas;
class FCanvas;
 
DECLARE_DYNAMIC_DELEGATE_RetVal_TwoParams(bool, FViewportDisplayCallback, FText&, OutText, FLinearColor&, OutColor);
 
typedef TFunction<bool(FText& OutTest, FLinearColor& OutColor)> FShouldDisplayFunc;
 
struct FViewportDisplayDelegate
{
    FViewportDisplayDelegate() = default;
 
    FViewportDisplayDelegate(FViewportDisplayCallback const& D) 
        : FuncDynDelegate(D)
    {};
 
    FViewportDisplayDelegate(FShouldDisplayFunc&& Callback)
        : FuncCallback(MoveTemp(Callback))
    {};
 
    FViewportDisplayCallback FuncDynDelegate;
    FShouldDisplayFunc FuncCallback;
 
    bool Execute(FText& OutText, FLinearColor& OutColor);
 
    inline bool IsBound() const { return FuncDynDelegate.IsBound() || FuncCallback; }
 
    void Unbind();
 
    // Movable only
    FViewportDisplayDelegate(FViewportDisplayDelegate&&) = default;
    FViewportDisplayDelegate(const FViewportDisplayDelegate&) = delete;
    FViewportDisplayDelegate& operator=(FViewportDisplayDelegate&&) = default;
    FViewportDisplayDelegate& operator=(const FViewportDisplayDelegate&) = delete;
};
 
UCLASS(Category = "Viewport Stats Subsystem", MinimalAPI)
class UViewportStatsSubsystem : public UWorldSubsystem
{
    GENERATED_BODY()
 
public:
 
    ENGINE_API void Draw(FViewport* Viewport, FCanvas* Canvas, UCanvas* CanvasObject, float MessageStartY);
 
    UFUNCTION(BlueprintCallable, Category = "Viewport Stats Subsystem", meta = (AutoCreateRefTerm = "DisplayOffset"))
    ENGINE_API void AddTimedDisplay(FText Text, FLinearColor Color = FLinearColor::White, float Duration = 0.0f, const FVector2D& DisplayOffset = FVector2D::ZeroVector);
 
    UFUNCTION(BlueprintCallable, Category = "Viewport Stats Subsystem")
    ENGINE_API int32 AddDisplayDelegate(FViewportDisplayCallback const& Delegate);
 
    ENGINE_API int32 AddDisplayDelegate(FShouldDisplayFunc&& Callback);
 
    UFUNCTION(BlueprintCallable, Category = "Viewport Stats Subsystem")
    ENGINE_API void RemoveDisplayDelegate(const int32 IndexToRemove);
    
protected:
 
    //~USubsystem interface
    ENGINE_API void Deinitialize() override;
    //~End of USubsystem interface
 
    struct FUniqueDisplayData
    {
        FUniqueDisplayData() = default;
 
        FUniqueDisplayData(const FText& Text, const FLinearColor& Col, const FVector2D& Offset = FVector2D::ZeroVector)
        : DisplayText(Text)
        , DisplayColor(Col)
        , DisplayOffset(Offset)
        {};
 
        FText DisplayText = FText::GetEmpty();
        FLinearColor DisplayColor = FLinearColor::White;
        FVector2D DisplayOffset = FVector2D::ZeroVector;
    };
 
    TArray<FViewportDisplayDelegate> DisplayDelegates;
 
    TArray<TSharedPtr<FUniqueDisplayData>> UniqueDisplayMessages;
};