Method getsize

tests/streamtests/streamtests.cc:176–184

    }

    static KTX_error_code getsize(ktxStream* str, ktx_size_t* size)
    {
        auto self = parent(str);
        const std::streampos oldpos = self->_streambuf->pubseekoff(0, std::ios::cur, self->_seek_mode);
        *size = ktx_size_t(self->_streambuf->pubseekoff(0, std::ios::end));
        const std::streampos newpos = self->_streambuf->pubseekoff(oldpos, std::ios::beg, self->_seek_mode);
        std::cerr << "\t  size: " << *size << 'B' << std::endl;
        return (oldpos == newpos) ? KTX_SUCCESS : KTX_FILE_SEEK_ERROR;
    }

    static void destruct(ktxStream* str)
    {