如何在 PlaybackTransportControlGlue android TV 上动态更改字幕答案

【问题标题】：How to change subtile dynamically on PlaybackTransportControlGlue android TV如何在 PlaybackTransportControlGlue android TV 上动态更改字幕
【发布时间】：2021-08-26 06:41:19
【问题描述】：

我正在为 Android TV 构建一个视频播放器应用。我正在使用 https://developer.android.com/training/tv/playback/transport-controls 中解释的 Exoplayer 依赖依赖项。到目前为止，我已经能够显示静态的视频标题，但我需要显示一个动态的字幕，它会随着视频播放的变化而变化。我该怎么做？下图显示了视频播放器的外观。我使用了一个字幕短语作为它应该出现的位置的占位符。

【问题讨论】：

标签： android exoplayer android-tv leanback

【解决方案1】：

我能够解决问题。我在 VideoSupportFragment 类 Player.EventListener 中添加了一个侦听器。这样：

class VideoFragment(mediaItems: Map<String, Any>) : VideoSupportFragment(), Player.EventListener {
private var playerAdapter: ExoPlayerAdapter? = null
private var _mediaItems: Map<String, Any>? = null
private lateinit var mMediaPlayerGlue: VideoMediaPlayerGlue<ExoPlayerAdapter>
private var mItems: List<*>? = null

init {
    _mediaItems = mediaItems
}

private val mHost: VideoSupportFragmentGlueHost = VideoSupportFragmentGlueHost(this)
private fun playWhenReady(glue: PlaybackGlue) {
    if (glue.isPrepared) {
        glue.play()
    } else {
        glue.addPlayerCallback(object : PlaybackGlue.PlayerCallback() {
            override fun onPreparedStateChanged(glue: PlaybackGlue) {
                if (glue.isPrepared) {
                    glue.removePlayerCallback(this);
                    glue.play()
                }
            }
        })
    }
}


override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    val mediaSource = _mediaItems?.get("media_source") as Map<*, *>
    playerAdapter = ExoPlayerAdapter(activity!!, _mediaItems!!)
    mMediaPlayerGlue =
        VideoMediaPlayerGlue(activity, playerAdapter!!)
    mMediaPlayerGlue.host = mHost;
    mMediaPlayerGlue.isControlsOverlayAutoHideEnabled = true
    mItems = mediaSource["media_items"] as List<*>
    mMediaPlayerGlue.title = mediaSource["title"] as CharSequence?

    mMediaPlayerGlue.playerAdapter.setDataSource()
    mMediaPlayerGlue.isSeekEnabled = true
    playerAdapter?.player?.addListener(this);

    playWhenReady(mMediaPlayerGlue)
}

override fun onPause() {
    super.onPause()
    playerAdapter?.player?.pause()
}

override fun onResume() {
    super.onResume()
    playerAdapter?.player?.play()
}

override fun onDestroy() {
    super.onDestroy()
    playerAdapter?.player?.removeListener(this);
}

override fun onMediaItemTransition(mediaItem: MediaItem?, reason: Int) {
    if (mItems?.size!! > 1){
        val item : Map<*, *> = mItems!![playerAdapter?.player?.currentWindowIndex!!] as Map<*, *>
        mMediaPlayerGlue.subtitle = item["subtitle"] as String
    }
}

}

【讨论】：