FontCacheHarfBuzz.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "Containers/StringView.h"
 
class FFreeTypeFace;
class FFreeTypeCacheDirectory;
struct FSlateFontInfo;
 
#ifndef WITH_HARFBUZZ
    #define WITH_HARFBUZZ 0
#endif // WITH_HARFBUZZ
 
#ifndef WITH_HARFBUZZ_V24
    #define WITH_HARFBUZZ_V24 0
#endif // WITH_HARFBUZZ_V24
 
#if PLATFORM_COMPILER_HAS_GENERIC_KEYWORD
    #define generic __identifier(generic)
#endif  //PLATFORM_COMPILER_HAS_GENERIC_KEYWORD
 
#if WITH_HARFBUZZ
    THIRD_PARTY_INCLUDES_START
    #include "hb.h"
    #include "hb-ft.h"
    THIRD_PARTY_INCLUDES_END
#endif // #if WITH_HARFBUZZ
 
#if PLATFORM_COMPILER_HAS_GENERIC_KEYWORD
    #undef generic
#endif  //PLATFORM_COMPILER_HAS_GENERIC_KEYWORD
 
namespace HarfBuzzUtils
{
 
#if WITH_HARFBUZZ
 
void AppendStringToBuffer(const FStringView InString, hb_buffer_t* InHarfBuzzTextBuffer);
 
void AppendStringToBuffer(const FStringView InString, const int32 InStartIndex, const int32 InLength, hb_buffer_t* InHarfBuzzTextBuffer);
 
#endif // #if WITH_HARFBUZZ
 
} // namespace HarfBuzzUtils
 
class FHarfBuzzFontCache
{
public:
    FHarfBuzzFontCache(FFreeTypeCacheDirectory* InFTCacheDirectory);
    ~FHarfBuzzFontCache();
 
#if WITH_HARFBUZZ
    hb_font_t* CreateFont(const FFreeTypeFace& InFace, const uint32 InGlyphFlags, const FSlateFontInfo& InFontInfo, const float InFontScale);
 
#endif // WITH_HARFBUZZ
    void Flush();
 
private:
    FFreeTypeCacheDirectory* FTCacheDirectory;
 
#if WITH_HARFBUZZ && WITH_FREETYPE
    class FFontKey
    {
    public:
        FFontKey(FT_Face InFace, const int32 InFlags);
 
        bool operator==(const FFontKey& Other) const
        {
            return Face == Other.Face
                && Flags == Other.Flags;
        }
 
        bool operator!=(const FFontKey& Other) const
        {
            return !(*this == Other);
        }
 
        friend inline uint32 GetTypeHash(const FFontKey& Key)
        {
            return Key.KeyHash;
        }
 
    private:
        FT_Face Face;
        const int32 Flags;
        uint32 KeyHash;
    };
    TMap<FFontKey, hb_face_t*> HarfBuzzFontCacheMap;
#endif // WITH_HARFBUZZ && WITH_FREETYPE
 
#if WITH_HARFBUZZ
    hb_font_funcs_t* CustomHarfBuzzFuncs;
#endif // WITH_HARFBUZZ
};