PngImageWrapper.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreTypes.h"
#include "ImageWrapperBase.h"
 
#if WITH_UNREALPNG
 
THIRD_PARTY_INCLUDES_START
    #include "zlib.h"
 
    // make sure no other versions of libpng headers are picked up
#if WITH_LIBPNG_1_6
    #include "ThirdParty/libPNG/libPNG-1.6.44/png.h"
    #include "ThirdParty/libPNG/libPNG-1.6.44/pngstruct.h"
    #include "ThirdParty/libPNG/libPNG-1.6.44/pnginfo.h"
#else
    #include "ThirdParty/libPNG/libPNG-1.5.2/png.h"
    #include "ThirdParty/libPNG/libPNG-1.5.2/pnginfo.h"
#endif
 
    #include <setjmp.h>
THIRD_PARTY_INCLUDES_END
 
 
class FPngImageWrapper
    : public FImageWrapperBase
{
public:
 
    FPngImageWrapper();
 
public:
 
    //~ FImageWrapper interface
 
    virtual void Compress(int32 Quality) override;
    virtual void Reset() override;
    virtual bool SetCompressed(const void* InCompressedData, int64 InCompressedSize) override;
    virtual void Uncompress(const ERGBFormat InFormat, int32 InBitDepth) override;
    
    virtual bool CanSetRawFormat(const ERGBFormat InFormat, const int32 InBitDepth) const override;
    virtual ERawImageFormat::Type GetSupportedRawFormat(const ERawImageFormat::Type InFormat) const override;
 
    virtual bool SupportsMetadata() const override;
 
    virtual void AddMetadata(const FString& InKey, const FString& InValue) override;
 
    virtual void GetMetadata(TStringMap& OutMetadata) const override;
 
public:
 
    bool IsPNG() const;
 
    bool LoadPNGHeader();
 
    void UncompressPNGData(const ERGBFormat InFormat, const int32 InBitDepth);
 
protected:
 
    // Callbacks for the pnglibs
    static void  user_read_compressed(png_structp png_ptr, png_bytep data, png_size_t length);
    static void  user_write_compressed(png_structp png_ptr, png_bytep data, png_size_t length);
    static void  user_flush_data(png_structp png_ptr);
    static void  user_error_fn(png_structp png_ptr, png_const_charp error_msg);
    static void  user_warning_fn(png_structp png_ptr, png_const_charp warning_msg);
    static void* user_malloc(png_structp png_ptr, png_size_t size);
    static void  user_free(png_structp png_ptr, png_voidp struct_ptr);
 
private:
 
    int64 ReadOffset;
 
    int32 ColorType;
 
    uint8 Channels;
 
#if PLATFORM_ANDROID
    //Other platforms rely on libPNG internal mechanism to achieve concurrent compression\decompression on multiple threads
    jmp_buf SetjmpBuffer;
#endif
 
    TMap<FString, FString> TextBlocks;
};
 
#endif  //WITH_UNREALPNG