LegacySlateFontInfoCache.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "UObject/GCObject.h"
#include "Fonts/CompositeFont.h"
 
class FLegacySlateFontInfoCache : public FGCObject, public TSharedFromThis<FLegacySlateFontInfoCache>
{
public:
    struct FFallbackContext
    {
    public:
        FFallbackContext() = default;
 
        FFallbackContext(const FFontData* InFontData, const UTF32CHAR InCodepoint)
            : FontData(InFontData)
            , Codepoint(InCodepoint)
        {
        }
 
        FString ToString() const;
 
    private:
        const FFontData* FontData = nullptr;
        UTF32CHAR Codepoint = 0;
    };
 
    static FLegacySlateFontInfoCache& Get();
 
    TSharedPtr<const FCompositeFont> GetCompositeFont(const FName& InLegacyFontName, const EFontHinting InLegacyFontHinting);
 
    TSharedRef<const FCompositeFont> GetDefaultFont();
 
    TSharedPtr<const FCompositeFont> GetSystemFont();
 
    bool IsLastResortFontAvailable() const;
 
    TSharedPtr<const FCompositeFont> GetLastResortFont();
 
    const FFontData& GetLastResortFontData(const FFallbackContext& InContext);
 
    // FGCObject interface
    virtual void AddReferencedObjects(FReferenceCollector& Collector) override;
    virtual FString GetReferencerName() const override;
 
private:
    FLegacySlateFontInfoCache();
 
    struct FLegacyFontKey
    {
        FLegacyFontKey()
            : Name()
            , Hinting(EFontHinting::Default)
        {
        }
 
        FLegacyFontKey(const FName& InName, const EFontHinting InHinting)
            : Name(InName)
            , Hinting(InHinting)
        {
        }
 
        bool operator==(const FLegacyFontKey& Other) const 
        {
            return Name == Other.Name && Hinting == Other.Hinting;
        }
 
        bool operator!=(const FLegacyFontKey& Other) const 
        {
            return !(*this == Other);
        }
 
        friend inline uint32 GetTypeHash(const FLegacyFontKey& Key)
        {
            uint32 Hash = 0;
            Hash = HashCombine(Hash, GetTypeHash(Key.Name));
            Hash = HashCombine(Hash, uint32(Key.Hinting));
            return Hash;
        }
 
        FName Name;
        EFontHinting Hinting;
    };
 
    TMap<FLegacyFontKey, TSharedPtr<const FCompositeFont>> LegacyFontNameToCompositeFont;
    TSharedPtr<const FCompositeFont> DefaultFont;
    TSharedPtr<const FCompositeFont> SystemFont;
    TSharedPtr<const FCompositeFont> LastResortFont;
    
    TSharedPtr<const FFontData> LocalizedFallbackFontData;
    TSharedPtr<const FFontData> LastResortFontData;
 
    FCriticalSection LastResortFontCS;
    FCriticalSection LastResortFontDataCS;
 
    FString LastResortFontPath;
    bool bIsLastResortFontAvailable;
 
    static TSharedPtr<FLegacySlateFontInfoCache> Singleton;
};