NavigationMethodProximity.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once 
 
#include "Input/HittestGrid.h"
#include "Input/NavigationMethod.h"
 
#include "NavigationMethodProximity.generated.h"
 
USTRUCT(DisplayName="Proximity")
struct FNavigationMethodProximity : public FNavigationMethod
{
    GENERATED_BODY()
 
public:     
    TSharedPtr<SWidget> FindNextFocusableWidget(const FArrangedWidget& StartingWidget, const EUINavigation Direction, const FNavigationReply& NavigationReply, const FArrangedWidget& RuleWidget, int32 InUserIndex) override;
 
    void Initialize(const FHittestGrid* InHittestGrid, TArray<FDebugWidgetResult>* InIntermediateResultsPtr) override;
 
private:
    UPROPERTY(EditAnywhere, Category = Navigation, meta = (ClampMin = "0.0", ClampMax = "2.0"))
    float AlignmentFactor = 1.0f;
 
    UPROPERTY(EditAnywhere, Category = Navigation, meta = (ClampMin = "0.0", ClampMax = "90.0", Units = "Degrees"))
    float SearchAngleDegrees = 45.0f;
 
    UPROPERTY(EditAnywhere, Category = Navigation, meta = (ClampMin = "0.0"))
    float OverlapThreshold = 20.0f;
 
private:
 
    struct FCellSearchInfo
    {
        FCellSearchInfo(const FNavigationMethodProximity* NavigationMethod, const FSlateRect& CurrentSearchRect, const FVector2f& SamplePoint, bool bWrapped)
            : NavigationMethod(NavigationMethod)
            , CurrentSearchRect(CurrentSearchRect)
            , CurrentCellPoint(FMath::RoundToInt(SamplePoint.X), FMath::RoundToInt(SamplePoint.Y))
            , StartingCellPoint(FMath::RoundToInt(SamplePoint.X), FMath::RoundToInt(SamplePoint.Y))
            , bWrapped(bWrapped)
        {}
 
        const FNavigationMethodProximity* NavigationMethod;
        FSlateRect CurrentSearchRect;
        FIntPoint CurrentCellPoint;
        FIntPoint StartingCellPoint;
        bool bWrapped : 1 ;
    };
 
    enum class ECellSearchResultAction
    {
        ContinueSearch,
        EndSearch,
        ApplyBoundaryRule
    };
 
    struct FCellSearchResult
    {
        TSharedPtr<SWidget> Widget;
        FSlateRect WidgetRect;
        FSlateRect SearchRect;
        float Distance = FLT_MAX;
        ECellSearchResultAction Action;
    };
 
    TSharedPtr<SWidget> FindFocusableWidgetFromRect(const FSlateRect WidgetRect, const FSlateRect BoundaryRect, const EUINavigation Direction, const FNavigationReply& NavigationReply, int32 UserIndex);
    FCellSearchResult FindBestWidgetInCell(const FCellSearchInfo& SearchInfo, const FSlateRect BoundaryRect, const EUINavigation Direction, const FNavigationReply& NavigationReply, int32 UserIndex);  
    void HandleBoundaryRule(const FSlateRect SourceRect, const FSlateRect BoundaryRect, const EUINavigation Direction, const FNavigationReply& NavigationReply, FCellSearchResult& OutCellResult, FCellSearchInfo& SearchInfo, TArray<FCellSearchInfo>& OutCellsToSearch);
    void PopulateCellsToSearch(const FSlateRect& SourceRect, EUINavigation Direction, bool bWrapped, TArray<FCellSearchInfo>& OutCellsToSearch);
    
    void CalculateSamplePoints(EUINavigation Direction, const FSlateRect& SourceRect, const FSlateRect& DestinationRect, FVector2f& OutSourcePoint, FVector2f& OutDestinationPoint) const;
    float CalculateDistance(EUINavigation Direction, const FSlateRect& SourceRect, const FSlateRect& DestinationRect) const;
 
    FVector2f GetSearchDirection(const EUINavigation Direction) const;
    void GetSearchPoints(const EUINavigation Direction, const FSlateRect& SourceRect, FVector2f& OutCellSearchPointMin, FVector2f& OutCellSearchPointMax) const;
    float GetSearchDirectionRadians(EUINavigation Direction) const;
 
    bool IsOutsideNavigationEdge(const EUINavigation Direction, const FSlateRect& SourceRect, const FSlateRect& DestinationRect) const;
    FSlateRect WrapRectWithinBoundary(const EUINavigation Direction, const FSlateRect& BoundaryRect, const FSlateRect& SourceRect) const;
 
    TSet<SWidget*> VisitedWidgets;
 
private:
#if WITH_SLATE_DEBUGGING
 
    struct FDrawDebugData
    {
        TArray<FVector2f> LabelPositions;
        TArray<float> Distances;
        TArray<FVector2f> Points;
        TArray<FLinearColor> Colors;
    };
 
    FDrawDebugData DrawDebugData;
 
    void PrepareDrawDebugData(const FSlateRect& SourceRect, EUINavigation Direction);
    void DebugCandidateDistance(EUINavigation Direction, const FSlateRect& SourceRect, const FSlateRect& DestinationRect, float Distance);
    void DebugSearchCell(const FCellSearchInfo& Cell);
    void DrawDebug(int32 InLayer, const FGeometry& AllottedGeometry, FSlateWindowElementList& WindowElementList);
 
#endif //WITH_SLATE_DEBUGGING
};