如何在 PlaybackTransportControlGlue android TV 上动态更改字幕

如何解决如何在 PlaybackTransportControlGlue android TV 上动态更改字幕

我正在为 Android TV 构建视频播放器应用。我正在使用 Exoplayer 的 Leanback 依赖项，如 https://developer.android.com/training/tv/playback/transport-controls 中所述。 到目前为止，我已经能够显示静态的视频标题，但是我需要显示一个动态的字幕，它会在视频播放发生变化时发生变化。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。

解决方法

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
    }
}

}