integration/Source/Integration/RadialMenu.h

//
// This class implements the layout calculatations for a radial
// menu.
//

#pragma once

#include "CoreMinimal.h"
#include "Components/Widget.h"
#include "RadialMenu.generated.h"

class SRadialMenu;
class UTexture2D;


USTRUCT(BlueprintType)
struct FRadialMenuConfig
{
    GENERATED_BODY()

    UPROPERTY(EditAnywhere, Category="RadialMenu")
    int32 NumItems = 8;

    UPROPERTY(EditAnywhere, Category="RadialMenu")
    float ItemHeight = 20.0f;

    UPROPERTY(EditAnywhere, Category="RadialMenu")
    float InnerRadius = 20.0f;

    UPROPERTY(EditAnywhere, Category="RadialMenu")
    float MinSpoke = 20.0f;

    UPROPERTY(EditAnywhere, Category="RadialMenu")
    float Spread = 20.0f;

    UPROPERTY(EditAnywhere, Category="RadialMenu")
    float LineThickness = 4.0f;

    UPROPERTY(EditAnywhere, Category="RadialMenu")
    FLinearColor LineColor = FLinearColor::White;

    UPROPERTY(EditAnywhere, Category="RadialMenu")
    TObjectPtr<UTexture2D> DotTexture;

    UPROPERTY(EditAnywhere, Category="RadialMenu")
    float DotRadius = 3.0f;

    UPROPERTY(EditAnywhere, Category="RadialMenu")
    int32 SelectedItem = -1;

    UPROPERTY(EditAnywhere, Category="RadialMenu")
    FLinearColor SelectedColor = FLinearColor::Yellow;

    UPROPERTY(EditAnywhere, Category="RadialMenu")
    float SelectedThickness = 2.0f;
};


USTRUCT(BlueprintType)
struct FRadialMenuItem
{
    GENERATED_BODY()

    UPROPERTY(BlueprintReadOnly)
    FVector2D Point1 = {0,0};

    UPROPERTY(BlueprintReadOnly)
    FVector2D Point2 = {0,0};

    UPROPERTY(BlueprintReadOnly)
    FVector2D Point3 = {0,0};

    UPROPERTY(BlueprintReadOnly)
    bool RightSide = false;

    static TArray<FRadialMenuItem> Calculate(const FRadialMenuConfig &Config);

private:
    using View = TArrayView<FRadialMenuItem>;

    // Give the unit vector for the selected spoke. NSide is
    // the number of spokes on the side of the wheel that
    // we're calculating, and NTotal is the total number of
    // spokes on both sides. The spokes on a given side are
    // organized top-to-bottom, and the angle between the
    // spokes is always equal to (1/NTotal) of the circle.
    static FVector2D SpokeVector(int32 I, int32 NSide, int32 NTotal);

    // Populate Point1 and Point2, these are the
    // endpoints of the spoke segment.  Spokes are
    // designed to always be long enough to make room
    // for MinSpoke, but also to make enough room to
    // keep the menu items from overlapping.
    static void CalculateSpokes(View V, int32 TotalItems, float ItemHeight, float InnerRadius, float MinSpoke);
    
    // Search for the widest spoke, and return its X coordinate.
    static double WidestSpoke(View V);

    // Populate Point3, this is the endpoint of the spread
    // line that goes horizontal.
    static void CalculateSpread(View V, double Offset);

    // Flip everything in the specified view horizontally.
    static void FlipHorizontal(View V);
};


UCLASS(BlueprintType, Blueprintable)
class URadialMenuWidget : public UWidget
{
    GENERATED_BODY()

public:
    UFUNCTION(BlueprintCallable)
    void SetNumItems(int32 NewNumItems);

    UFUNCTION(BlueprintCallable)
    void SetItemHeight(float NewItemHeight);

    UFUNCTION(BlueprintCallable)
    void SetInnerRadius(float NewInnerRadius);

    UFUNCTION(BlueprintCallable)
    void SetMinSpoke(float NewMinSpoke);

    UFUNCTION(BlueprintCallable)
    void SetSpread(float NewSpread);

    UFUNCTION(BlueprintCallable)
    void SetLineThickness(float NewLineThickness);

    UFUNCTION(BlueprintCallable)
    void SetLineColor(FLinearColor NewLineColor);

    UFUNCTION(BlueprintCallable)
    void SetDotTexture(UTexture2D* NewDotTexture);

    UFUNCTION(BlueprintCallable)
    void SetDotRadius(float NewDotRadius);

    UFUNCTION(BlueprintCallable)
    bool SetSelectedItem(int32 NewSelectedItem);

    UFUNCTION(BlueprintCallable)
    void SetSelectedColor(FLinearColor NewSelectedColor);

    UFUNCTION(BlueprintCallable)
    void SetSelectedThickness(float NewSelectedThickness);

    UFUNCTION(BlueprintCallable)
    const TArray<FRadialMenuItem> &GetItems() const { return Items; }

    // Returns true if the selected item changed.
    UFUNCTION(BlueprintCallable)
    bool AddPointer(FVector2D Direction, float Scale);

    UFUNCTION(BlueprintCallable)
    FVector2D GetPointer() const { return PointerVector; }
    
    UFUNCTION(BlueprintCallable)
    FLinearColor GetItemColor(int N) const;
    
protected:
    UPROPERTY(EditAnywhere)
    FRadialMenuConfig Config;

    TArray<FRadialMenuItem> Items;

    FVector2D PointerVector = {0,0};

    virtual TSharedRef<SWidget> RebuildWidget() override;
    virtual void ReleaseSlateResources(bool bReleaseChildren) override;
    virtual void SynchronizeProperties() override;

    TSharedPtr<SRadialMenu> MySlateWidget;
};