GameViewportSubsystem.h

Go to the documentation of this file.

// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "Subsystems/EngineSubsystem.h"
#include "Layout/Margin.h"
#include "UObject/ObjectKey.h"
#include "Widgets/Layout/Anchors.h"
#include "Widgets/Layout/SConstraintCanvas.h"
#include "GameViewportSubsystem.generated.h"
 
class ULevel;
class ULocalPlayer;
class UWidget;
class UWorld;
class SConstraintCanvas;
 
USTRUCT(BlueprintType)
struct FGameViewportWidgetSlot
{
    GENERATED_BODY()
 
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "User Interface")
    FAnchors Anchors = FAnchors(0.f, 0.f, 1.f, 1.f);
 
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "User Interface")
    FMargin Offsets;
 
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "User Interface")
    FVector2D Alignment = FVector2D(0.f, 0.f);
 
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "User Interface")
    int32 ZOrder = 0;
 
    UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "User Interface")
    bool bAutoRemoveOnWorldRemoved = true;
};
 
 
UCLASS(MinimalAPI)
class UGameViewportSubsystem : public UEngineSubsystem
{
    GENERATED_BODY()
 
public:
    //~ Begin Subsystem
    UMG_API virtual void Initialize(FSubsystemCollectionBase& Collection) override;
    UMG_API virtual void Deinitialize() override;
    //~ End Subsystem
 
    static UMG_API UGameViewportSubsystem* Get();
    static UMG_API UGameViewportSubsystem* Get(UWorld* World);
    
public:
    /* @return true if the widget was added to the viewport using AddWidget or AddWidgetForPlayer. */
    UFUNCTION(BlueprintPure, BlueprintCosmetic, Category = "User Interface")
    UMG_API bool IsWidgetAdded(const UWidget* Widget) const;
 
    UFUNCTION(BlueprintCallable, BlueprintCosmetic, Category = "User Interface")
    UMG_API bool AddWidget(UWidget* Widget, FGameViewportWidgetSlot Slot);
 
    UFUNCTION(BlueprintCallable, BlueprintCosmetic, Category = "User Interface")
    UMG_API bool AddWidgetForPlayer(UWidget* Widget, ULocalPlayer* Player, FGameViewportWidgetSlot Slot);
 
    UFUNCTION(BlueprintCallable, BlueprintCosmetic, Category = "User Interface")
    UMG_API void RemoveWidget(UWidget* Widget);
 
    /* The slot info from previously added widget or info that is store for later. */
    UFUNCTION(BlueprintCallable, BlueprintCosmetic, Category = "User Interface")
    UMG_API FGameViewportWidgetSlot GetWidgetSlot(const UWidget* Widget) const;
 
    /* Update the slot info of a previously added widget or Store the slot info for later use. */
    UFUNCTION(BlueprintCallable, BlueprintCosmetic, Category = "User Interface")
    UMG_API void SetWidgetSlot(UWidget* Widget, FGameViewportWidgetSlot Slot);
 
    DECLARE_EVENT_TwoParams(UGameViewportSubsystem, FWidgetAddedEvent, UWidget*, ULocalPlayer*);
    FWidgetAddedEvent OnWidgetAdded;
 
    DECLARE_EVENT_OneParam(UGameViewportSubsystem, FWidgetRemovedEvent, UWidget*);
    FWidgetRemovedEvent OnWidgetRemoved;
 
public:
    UFUNCTION(BlueprintCallable, Category = "GameViewportWidgetSlot")
    static UMG_API FGameViewportWidgetSlot SetWidgetSlotPosition(FGameViewportWidgetSlot Slot, const UWidget* Widget, FVector2D Position, bool bRemoveDPIScale);
 
    UFUNCTION(BlueprintCallable, Category = "GameViewportWidgetSlot")
    static UMG_API FGameViewportWidgetSlot SetWidgetSlotDesiredSize(FGameViewportWidgetSlot Slot, FVector2D Size);
 
private:
    struct FSlotInfo
    {
        FGameViewportWidgetSlot Slot;
        TWeakObjectPtr<ULocalPlayer> LocalPlayer;
        TWeakPtr<SConstraintCanvas> FullScreenWidget;
        SConstraintCanvas::FSlot* FullScreenWidgetSlot = nullptr;
    };
 
private:
    bool AddToScreen(UWidget* Widget, ULocalPlayer* Player, FGameViewportWidgetSlot& Slot);
    void RemoveWidgetInternal(UWidget* Widget, const TWeakPtr<SConstraintCanvas>& FullScreenWidget, const TWeakObjectPtr<ULocalPlayer>& LocalPlayer);
    void HandleWorldCleanup(UWorld* InWorld, bool bSessionEnded, bool bCleanupResoures);
    void HandleRemoveWorld(UWorld* InWorld);
    void HandleLevelRemovedFromWorld(ULevel* InLevel, UWorld* InWorld);
 
    FMargin GetFullScreenOffsetForWidget(UWidget* Widget) const;
    TPair<FMargin, bool> GetOffsetAttribute(UWidget* Widget, const FGameViewportWidgetSlot& Slot) const;
 
private:
    using FViewportWidgetList = TMap<TObjectKey<UWidget>, FSlotInfo>;
    FViewportWidgetList ViewportWidgets;
};