FDockingDragOperation.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "Layout/SlateRect.h"
#include "Input/DragAndDrop.h"
#include "Framework/Docking/SDockingNode.h"
#include "Framework/Docking/SDockingArea.h"
#include "Widgets/Docking/SDockTab.h"
#include "Framework/Docking/SDockingTabStack.h"
#include "Framework/Docking/SDockingTabWell.h"
 
class FDockingDragOperation : public FDragDropOperation
{
public:
 
    DRAG_DROP_OPERATOR_TYPE(FDockingDragOperation, FDragDropOperation)
 
    
    struct FDockTarget
    {
        FDockTarget()
        : TargetNode()
        , DockDirection()
        {
        }
 
        FDockTarget( const TSharedPtr<class SDockingNode>& InTargetNode, SDockingNode::RelativeDirection InDockDirection )
        : TargetNode( InTargetNode )
        , DockDirection( InDockDirection )
        {
        }
 
        bool operator==( const FDockTarget& Other )
        {
            return
                this->TargetNode == Other.TargetNode &&
                this->DockDirection == Other.DockDirection;
        }
 
        bool operator!=( const FDockTarget& Other )
        {
            return !((*this)==Other);
        }
 
        TWeakPtr<class SDockingNode> TargetNode;
        SDockingNode::RelativeDirection DockDirection;
    };
 
    virtual void OnDrop( bool bDropWasHandled, const FPointerEvent& MouseEvent ) override;
 
    virtual void OnDragged( const FDragDropEvent& DragDropEvent ) override;
    
    void OnTabWellEntered( const TSharedRef<class SDockingTabWell>& ThePanel );
 
    void OnTabWellLeft( const TSharedRef<class SDockingTabWell>& ThePanel, const FGeometry& DockNodeGeometry );
 
    FSlateRect GetPreviewAreaForDirection ( const FSlateRect& DockableArea, SDockingArea::RelativeDirection DockingDirection );
 
    void SetHoveredTarget( const FDockTarget& InTarget, const FInputEvent& InputEvent );
 
    static TSharedRef<FDockingDragOperation> New( const TSharedRef<SDockTab>& InTabToBeDragged, const FVector2D InTabGrabOffset, TSharedRef<class SDockingArea> InTabOwnerArea, const FVector2D& OwnerAreaSize );
 
    TSharedPtr<SDockTab> GetTabBeingDragged();
 
    FVector2D GetTabGrabOffsetFraction() const;
 
    enum EViaTabwell
    {
        DockingViaTabWell,
        DockingViaTarget
    };
 
    bool CanDockInNode( const TSharedRef<SDockingNode>& DockNode, EViaTabwell IsDockingViaTabwell ) const;
 
    virtual ~FDockingDragOperation();
 
protected:
    FDockingDragOperation( const TSharedRef<class SDockTab>& InTabToBeDragged, const FVector2D InTabGrabOffsetFraction, TSharedRef<class SDockingArea> InTabOwnerArea, const FVector2D& OwnerAreaSize );
 
    const FVector2D GetDecoratorOffsetFromCursor();
 
    static FVector2D DesiredSizeFrom( const FVector2D& InitialTabSize );
 
    void DroppedOntoNothing();
 
    TSharedPtr<class SDockTab> TabBeingDragged;
 
    FVector2D TabGrabOffsetFraction;
 
    TSharedPtr<SDockingArea> TabOwnerAreaOfOrigin;
 
    TSharedPtr<SDockingTabStack> CursorDecoratorStackNode;
 
    TWeakPtr<class SDockingTabStack> TabStackOfOrigin;
 
    TWeakPtr<class SDockingTabWell> HoveredTabPanelPtr;
 
    FDockTarget HoveredDockTarget;
 
    FVector2D LastContentSize;
};