Method read

tests/fl/fx/video.cpp:50–58

        return bytes_written / 3;
    }
    size_t read(char *dst, size_t bytesToRead) override {
        size_t bytesRead = 0;
        while (bytesRead < bytesToRead && mPos < data.size()) {
            dst[bytesRead] = static_cast<char>(data[mPos]);
            bytesRead++;
            mPos++;
        }
        return bytesRead;
    }
    using fl::filebuf::read; // u8 overload
    size_t write(const char *dat, size_t count) override {
        (void)dat; (void)count;