UMGDragDropOp.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "Input/CursorReply.h"
#include "Input/DragAndDrop.h"
#include "UObject/GCObject.h"
 
class SObjectWidget;
class SWidget;
class UDragDropOperation;
class UGameViewportClient;
 
class FUMGDragDropOp : public FGameDragDropOperation, public FGCObject
{
public:
    DRAG_DROP_OPERATOR_TYPE(FUMGDragDropOp, FGameDragDropOperation)
    
    UMG_API static TSharedRef<FUMGDragDropOp> New(UDragDropOperation* Operation, const int32 PointerIndex, const FVector2D &CursorPosition, const FVector2D &ScreenPositionOfNode, float DPIScale, TSharedPtr<SObjectWidget> SourceUserWidget);
 
    FUMGDragDropOp();
 
    // Begin FGCObject
    virtual void AddReferencedObjects(FReferenceCollector& Collector) override;
    virtual FString GetReferencerName() const override;
    // End FGCObject
 
    virtual bool AffectedByPointerEvent(const FPointerEvent& PointerEvent) override;
    virtual void OnDrop( bool bDropWasHandled, const FPointerEvent& MouseEvent ) override;
    virtual void OnDragged( const class FDragDropEvent& DragDropEvent ) override;
    virtual FCursorReply OnCursorQuery() override;
    virtual TSharedPtr<SWidget> GetDefaultDecorator() const override;
 
    UDragDropOperation* GetOperation() const { return DragOperation; }
 
protected:
    virtual void Construct() override;
 
private:
 
    // Raw pointer to the drag operation, kept alive by AddReferencedObjects.
    TObjectPtr<UDragDropOperation> DragOperation;
 
    TWeakPtr<SObjectWidget> SourceUserWidget;
 
    TWeakObjectPtr<UGameViewportClient> GameViewport;
 
    TSharedPtr<SWidget> DecoratorWidget;
 
    FVector2D MouseDownOffset;
 
    FVector2D StartingScreenPos;
 
    int32 PointerIndex;
 
    double StartTime;
};