SWidgetSwitcher.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "Misc/Attribute.h"
#include "Layout/Visibility.h"
#include "Widgets/DeclarativeSyntaxSupport.h"
#include "Widgets/SWidget.h"
#include "SlotBase.h"
#include "Layout/Children.h"
#include "Widgets/SPanel.h"
 
class FArrangedChildren;
 
class SWidgetSwitcher
    : public SPanel
{
public:
 
    using FSlot = FBasicLayoutWidgetSlot;
 
    SLATE_BEGIN_ARGS(SWidgetSwitcher)
        : _WidgetIndex(0)
        {
            _Visibility = EVisibility::SelfHitTestInvisible;
        }
 
        SLATE_SLOT_ARGUMENT(FSlot, Slots)
 
        
        SLATE_ATTRIBUTE(int32, WidgetIndex)
 
    SLATE_END_ARGS()
 
    SLATE_API SWidgetSwitcher();
    SLATE_API virtual ~SWidgetSwitcher();
 
public:
 
    using FScopedWidgetSlotArguments = TPanelChildren<FSlot>::FScopedWidgetSlotArguments;
    SLATE_API FScopedWidgetSlotArguments AddSlot( int32 SlotIndex = INDEX_NONE );
 
    SLATE_API void Construct( const FArguments& InArgs );
 
    SLATE_API TSharedPtr<SWidget> GetActiveWidget( ) const;
 
    int32 GetActiveWidgetIndex( ) const
    {
        return WidgetIndex.Get();
    }
 
    int32 GetNumWidgets( ) const
    {
        return AllChildren.Num();
    }
 
    SLATE_API TSharedPtr<SWidget> GetWidget( int32 SlotIndex ) const;
 
    SLATE_API int32 GetWidgetIndex( TSharedRef<SWidget> Widget ) const;
 
    SLATE_API int32 RemoveSlot( TSharedRef<SWidget> WidgetToRemove );
 
    void SetActiveWidget( TSharedRef<SWidget> Widget )
    {
        SetActiveWidgetIndex(GetWidgetIndex(Widget));
    }
 
    SLATE_API void SetActiveWidgetIndex( int32 Index );
 
    SLATE_API virtual bool ValidatePathToChild(SWidget* InChild) override;
 
public:
 
    static SLATE_API FSlot::FSlotArguments Slot();
 
protected:
 
    // SCompoundWidget interface
 
    SLATE_API virtual void OnArrangeChildren( const FGeometry& AllottedGeometry, FArrangedChildren& ArrangedChildren ) const override;
    SLATE_API virtual FVector2D ComputeDesiredSize( float ) const override;
    SLATE_API virtual FChildren* GetChildren( ) override;
    virtual void OnSlotAdded(int32 AddedIndex) {}
    virtual void OnSlotRemoved(int32 RemovedIndex, TSharedRef<SWidget> RemovedWidget, bool bWasActiveSlot) {}
    virtual bool ComputeVolatility() const override { return WidgetIndex.IsBound(); }
    SLATE_API const FSlot* GetActiveSlot() const;
 
    TPanelChildren<FSlot>& GetTypedChildren() { return AllChildren; }
 
private:
 
    TAttribute<int32> WidgetIndex;
 
    /*
     * Holds the collection of all child widget, however the only one with a valid parent pointer
     * will be the one in the dynamic slot.
     */
    TPanelChildren<FSlot> AllChildren;
 
    TOneDynamicChild<FSlot> OneDynamicChild;
 
#if WITH_ACCESSIBILITY
    TWeakPtr<SWidget> LastActiveWidget;
#endif
};