IRun.h

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// Copyright Epic Games, Inc. All Rights Reserved.
#pragma once
 
#include "CoreMinimal.h"
#include "Framework/Text/ShapedTextCacheFwd.h"
#include "Misc/EnumClassFlags.h"
 
class ILayoutBlock;
class IRunRenderer;
enum class ETextHitPoint : uint8;
enum class ETextShapingMethod : uint8;
 
struct FRunInfo
{
    FRunInfo()
        : Name()
        , MetaData()
    {
    }
 
    FRunInfo( FString InName )
        : Name( MoveTemp(InName) )
        , MetaData()
    {
 
    }
 
    FString Name;
    TMap< FString, FString > MetaData;
};
 
enum class ERunAttributes : uint8
{
    None = 0,
 
    SupportsText = 1<<0,
};
ENUM_CLASS_FLAGS(ERunAttributes);
 
struct FShapedTextContext
{
    FShapedTextContext(const ETextShapingMethod InTextShapingMethod, const TextBiDi::ETextDirection InBaseDirection)
        : TextShapingMethod(InTextShapingMethod)
        , BaseDirection(InBaseDirection)
    {
    }
 
    inline bool operator==(const FShapedTextContext& Other) const
    {
        return TextShapingMethod == Other.TextShapingMethod
            && BaseDirection == Other.BaseDirection;
    }
 
    inline bool operator!=(const FShapedTextContext& Other) const
    {
        return !(*this == Other);
    }
 
    friend inline uint32 GetTypeHash(const FShapedTextContext& Key)
    {
        uint32 KeyHash = 0;
        KeyHash = HashCombine(KeyHash, GetTypeHash(Key.TextShapingMethod));
        KeyHash = HashCombine(KeyHash, GetTypeHash(Key.BaseDirection));
        return KeyHash;
    }
 
    ETextShapingMethod TextShapingMethod;
 
    TextBiDi::ETextDirection BaseDirection;
};
 
struct FRunTextContext : public FShapedTextContext
{
    FRunTextContext(const ETextShapingMethod InTextShapingMethod, const TextBiDi::ETextDirection InBaseDirection, FShapedTextCacheRef InShapedTextCache)
        : FShapedTextContext(InTextShapingMethod, InBaseDirection)
        , ShapedTextCache(InShapedTextCache)
    {
    }
 
    FShapedTextCacheRef ShapedTextCache;
};
 
struct FLayoutBlockTextContext : public FRunTextContext
{
    FLayoutBlockTextContext(const FRunTextContext& InRunTextContext, const TextBiDi::ETextDirection InTextDirection)
        : FRunTextContext(InRunTextContext)
        , TextDirection(InTextDirection)
    {
    }
 
    inline bool operator==(const FLayoutBlockTextContext& Other) const
    {
        return FRunTextContext::operator==(Other)
            && TextDirection == Other.TextDirection;
    }
 
    inline bool operator!=(const FLayoutBlockTextContext& Other) const
    {
        return !(*this == Other);
    }
 
    friend inline uint32 GetTypeHash(const FLayoutBlockTextContext& Key)
    {
        uint32 KeyHash = GetTypeHash(static_cast<const FRunTextContext&>(Key));
        KeyHash = HashCombine(KeyHash, GetTypeHash(Key.TextDirection));
        return KeyHash;
    }
 
    TextBiDi::ETextDirection TextDirection;
};
 
class IRun
{
public:
 
    virtual ~IRun() {}
 
    virtual FTextRange GetTextRange() const = 0;
    virtual void SetTextRange( const FTextRange& Value ) = 0;
 
    virtual int16 GetBaseLine( float Scale ) const = 0;
    virtual int16 GetMaxHeight( float Scale ) const = 0;
 
    virtual FVector2D Measure( int32 StartIndex, int32 EndIndex, float Scale, const FRunTextContext& TextContext) const = 0;
    virtual int8 GetKerning(int32 CurrentIndex, float Scale, const FRunTextContext& TextContext) const = 0;
    virtual FVector2D GetOutlineSize(int32 StartIndex, int32 EndIndex, float Scale) const { return FVector2d::ZeroVector; }
    virtual FVector2D GetShadowSize(int32 StartIndex, int32 EndIndex, float Scale) const { return FVector2d::ZeroVector; }
 
    virtual TSharedRef< class ILayoutBlock > CreateBlock( int32 StartIndex, int32 EndIndex, FVector2D Size, const FLayoutBlockTextContext& TextContext, const TSharedPtr< class IRunRenderer >& Renderer ) = 0;
 
    virtual int32 GetTextIndexAt( const TSharedRef< ILayoutBlock >& Block, const FVector2D& Location, float Scale, ETextHitPoint* const OutHitPoint = nullptr ) const = 0;
    
    virtual FVector2D GetLocationAt(const TSharedRef< ILayoutBlock >& Block, int32 Offset, float Scale) const = 0;
 
    virtual void BeginLayout() = 0;
    virtual void EndLayout() = 0;
 
    virtual void Move(const TSharedRef<FString>& NewText, const FTextRange& NewRange) = 0;
    virtual TSharedRef<IRun> Clone() const = 0;
 
    virtual void AppendTextTo(FString& Text) const = 0;
    virtual void AppendTextTo(FString& Text, const FTextRange& Range) const = 0;
 
    virtual const FRunInfo& GetRunInfo() const = 0;
 
    virtual ERunAttributes GetRunAttributes() const = 0;
 
};