Exoplayer正在使用PageTransformer删除预览

Question

我有一个带有CubeTransformer的viewPager，它正在转换每个片段。在每个片段内都是图像或视频视图（使用Exoplayer）。而且，当您尝试通过转换更改framgnet时，exoplayer会丢失预览（我黑屏了），即使它没有播放。但是在将条件更改为正常后，预览又回来了

相反，如果您要删除pageTransformer，则不会消失。如何使预览始终显示在屏幕上？

CubeTransformer

class CubeTransformer : ViewPager.PageTransformer {
    override fun transformPage(view: View, position: Float) {
        if (view.visibility != View.VISIBLE) return

        view.apply {
            cameraDistance = (view.width * distanceMultiplier).toFloat()
            pivotX = if (position < 0f) view.width.toFloat() else 0f
            pivotY = view.height * 0.5f
            rotationY = 90f * position

            if (position < -1 || position > 1) {
                alpha = 0f // item not visible
            } else {
                alpha = 1f
            }
        }
    }

    private companion object {
        private const val distanceMultiplier: Int = 20
    }
}

VideoView

class VideoView(context: Context) : ConstraintLayout(context, null) {
    private val player = ExoPlayerFactory.newSimpleInstance(context, DefaultTrackSelector(), DefaultLoadControl())
    private val dataSourceFactory = DefaultDataSourceFactory(context, "android")

    private lateinit var model: Model

    init {
        inflate(context, R.layout.story_item_video, this)
        video_view.player = player
        video_view.keepScreenOn = true
        video_view.setBackgroundColor(Color.TRANSPARENT)
        video_view.setShutterBackgroundColor(Color.TRANSPARENT)
    }

    fun setData(model: Model?) {
        if (model== null) return

        this.model = model

        val mediaSource = HlsMediaSource
                .Factory(dataSourceFactory)
                .setExtractorFactory(DefaultHlsExtractorFactory())
                .createMediaSource(Uri.parse(model.streamLink))

        player.playWhenReady = true
        player.prepare(mediaSource)

        player.addListener(object: Player.EventListener {
            override fun onPlaybackParametersChanged(playbackParameters: PlaybackParameters?) {
            }

            override fun onSeekProcessed() {}

            override fun onTracksChanged(trackGroups: TrackGroupArray?, trackSelections: TrackSelectionArray?) {
            }

            override fun onPlayerError(error: ExoPlaybackException?) {
            }

            override fun onLoadingChanged(isLoading: Boolean) {
            }

            override fun onPositionDiscontinuity(reason: Int) {
            }

            override fun onRepeatModeChanged(repeatMode: Int) {
            }

            override fun onShuffleModeEnabledChanged(shuffleModeEnabled: Boolean) {
            }

            override fun onTimelineChanged(timeline: Timeline?, manifest: Any?, reason: Int) {
            }

            override fun onPlayerStateChanged(playWhenReady: Boolean, playbackState: Int) {

            }
        })
    }
}