Hi, I’m showing countdown timer on ui served from ...

# orbit-mvi

[Ravi]

Hi, I’m showing countdown timer on ui served from viewModel .
MVI state

data class VideoState(val currentTime: Long, 
                      val totalTime: Long,
                      val title: String)

UI (Fragment)

renderData(state: VideoState) {
 binding.timerTextView.text = "$state.currentTime"
 binding.durationTextView.text = "$state.totalTime"
 binding.title = "$state.title"
}

only timerTextView will update but durationTextView & title will remain same still renderData will set everything. Is there any performance again if we want to update part of the view? If so whats the better to do that? Hoping for a onBindViewHolder with payload kind of approach

[Ravi]

I’ve checked PostDetailsViewModel , please let me know if below approach is correct or not .

data class VideoData(
    val url: String = "",
    val title: String = "",
    val isPlaying: Boolean = false,
    val totalDuration: Long = 0L,
)

sealed class VideoState {

    abstract val videoData: VideoData

    data class VideoMeta(override val videoData: VideoData) : VideoState()

    data class VideTimer(val currentTime: Long, override val videoData: VideoData) : VideoState()
}

class VideoViewModel(private val someSubject: SomeSubject, private val someRepo: SomeRepo) : ViewModel(), ContainerHost<VideoState, Nothing> {

    override val container by lazy {
        container<VideoState, Nothing>(
            initialState = VideoState.VideoMeta(VideoData()),
        ) { initData() }
    }

    private fun initData() = intent {
        val videoData: VideoData = someRepo.fetchVideoMeta()
        reduce {
            with(videoData) {
                VideoState.VideoMeta(state.videoData.copy(url = url, title = title, totalDuration = totalDuration))
            }
        }
        repeatOnSubscription {
            val timer: Long = someSubject.listentoTimer()
            reduce {
                VideoState.VideTimer(currentTime = timer, videoData = state.videoData)
            }
        }
    }
}

class VideoFragment : Fragment() {

    fun renderData(state: VideoState) {
        when (state) {
            is VideoState.VideTimer -> binding.timerTv.text = "${state.currentTime}"
            is VideoState.VideoMeta -> with(state.videoData) {
                binding.titleTv.text = "$title"
                binding.totalTv.text = "$totalDuration"
                binding.playIcon.background = if (isPlaying) playIcon else pauseIcon
            }
        }
    }
}