Method encode

modules/engine/image_coder/src/image_coder_png.cpp:271–340

}

bool PNGImageEncoder::encode() SKR_NOEXCEPT
{
    SKR_ASSERT(initialized);
    const auto width = get_width();
    const auto height = get_height();
    const auto color_format = get_color_format();
    const auto raw_bit_depth = get_bit_depth();

    //Preserve old single thread code on some platform in relation to a type incompatibility at compile time.
    SKR_ASSERT(width > 0);
    SKR_ASSERT(height > 0);

    // Reset to the beginning of file so we can use png_read_png(), which expects to start at the beginning.
    read_offset = 0;

    png_structp png_ptr	= png_create_write_struct(PNG_LIBPNG_VER_STRING, this, PNGImageCoderHelper::user_error_fn, PNGImageCoderHelper::user_warning_fn);
    SKR_ASSERT(png_ptr);

    png_infop info_ptr	= png_create_info_struct(png_ptr);
    SKR_ASSERT(info_ptr);

    png_bytep* row_pointers = (png_bytep*) png_malloc( png_ptr, height * sizeof(png_bytep) );
    SKR_DEFER({ png_free(png_ptr, row_pointers); png_destroy_write_struct(&png_ptr, &info_ptr); });

    // Store the current stack pointer in the jump buffer. setjmp will return non-zero in the case of a write error.
#if PLATFORM_ANDROID || PLATFORM_LUMIN || PLATFORM_LUMINGL4
    //Preserve old single thread code on some platform in relation to a type incompatibility at compile time.
    if (setjmp(SetjmpBuffer) != 0)
#else
    //Use libPNG jump buffer solution to allow concurrent compression\decompression on concurrent threads.
    if (setjmp(png_jmpbuf(png_ptr)) != 0)
#endif
    {
        return false;
    }

    // ---------------------------------------------------------------------------------------------------------
    // Anything allocated on the stack after this point will not be destructed correctly in the case of an error

    {
        png_set_compression_level(png_ptr, PNGDefaultZlibLevel);
        //png_set_IHDR(png_ptr, info_ptr, width, height, raw_bit_depth, 
        //    (color_format == EImageCoderColorFormat::IMAGE_CODER_COLOR_FORMAT_Gray) ? PNG_COLOR_TYPE_GRAY : PNG_COLOR_TYPE_RGBA,
        //    PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
        png_set_write_fn(png_ptr, this, PNGImageCoderHelper::user_write_compressed, PNGImageCoderHelper::user_flush_data);

        const uint64_t PixelChannels = (color_format == EImageCoderColorFormat::IMAGE_CODER_COLOR_FORMAT_Gray) ? 1 : 4;
        const uint64_t BytesPerPixel = (raw_bit_depth * PixelChannels) / 8;
        const uint64_t BytesPerRow = BytesPerPixel * width;

        for (int64_t i = 0; i < height; i++)
        {
            auto dv = decoded_view.data();
            row_pointers[i] = (png_bytep)&dv[i * BytesPerRow];
        }
        png_set_rows(png_ptr, info_ptr, row_pointers);

        uint32_t Transform = (color_format == EImageCoderColorFormat::IMAGE_CODER_COLOR_FORMAT_BGRA) ? PNG_TRANSFORM_BGR : PNG_TRANSFORM_IDENTITY;