使用 Leanback 傳輸控制項

Leanback Androidx 程式庫提供新的播放控制項,可提供更優質的使用者體驗。以影片應用程式來說,傳輸控制項支援透過向前/向後控制項拖曳影片。拖曳顯示畫面時會顯示縮圖,協助使用者瀏覽影片。

程式庫包含抽象類別和立即可用的實作,可為開發人員提供更精細的控制項。透過預先建構的實作項目,不必編寫大量程式碼,就能快速建構功能豐富的應用程式。如要進一步自訂,您可以擴充任何程式庫的預先建構元件。

控制項和播放器

Leanback 程式庫會將 UI 與傳輸控制項與播放後影片的播放器分隔開來。為此,我們透過兩個元件完成這項操作:顯示傳輸控制項 (和選用影片) 的播放支援片段,以及用於封裝媒體播放器的播放器轉接程式

播放片段

應用程式的 UI 活動應使用 PlaybackSupportFragmentVideoSupportFragment。兩者都含有 leanback 傳輸控制項:

您可以自訂片段的 ObjectAdapter,改善 UI。例如,使用 setAdapter() 新增「相關影片」列。

播放器轉接器

PlayerAdapter 是控制基礎媒體播放器的抽象類別。開發人員可以選擇預先建構的 MediaPlayerAdapter 實作,或是自行編寫這個類別的實作。

一起黏著所提供的拼圖

您必須使用某些「控制黏膠」將播放片段連結至播放器。leanback 程式庫提供兩種黏膠:

Leanback 運輸控制黏膠

如要讓應用程式支援影片拖曳功能,您必須使用 PlaybackTransportControlGlue

您還需要指定可繫結至播放片段的「黏附主機」,在 UI 中繪製傳輸控制項並維持狀態,以及將傳輸控制事件傳回至膠卷。主機必須與播放片段類型相符。將 PlaybackSupportFragmentGlueHostPlaybackFragment 搭配使用,將 VideoSupportFragmentGlueHostVideoFragment 搭配使用。

下圖顯示 leanback 運輸控制項如何搭配運作:

Leanback 運輸控制黏膠

會同時連貫應用程式的程式碼應位於定義 UI 的 PlaybackSupportFragmentVideoSupportFragment 中。

在以下範例中,應用程式會建構 PlaybackTransportControlGlue 執行個體、將其命名為 playerGlue,並將 VideoSupportFragment 連結至新建立的 MediaPlayerAdapter。由於這是 VideoSupportFragment,設定程式碼會呼叫 setHost() 以將 VideoSupportFragmentGlueHost 附加至 playerGlue。程式碼包含在擴充 VideoSupportFragment 的類別內。

Kotlin

class MyVideoFragment : VideoSupportFragment() {

  fun onCreate(savedInstanceState: Bundle) {
      super.onCreate(savedInstanceState)
      val playerGlue = PlaybackTransportControlGlue(getActivity(),
          MediaPlayerAdapter(getActivity()))
      playerGlue.setHost(VideoSupportFragmentGlueHost(this))
      playerGlue.addPlayerCallback(object : PlaybackGlue.PlayerCallback() {
          override fun onPreparedStateChanged(glue: PlaybackGlue) {
              if (glue.isPrepared()) {
                  playerGlue.seekProvider = MySeekProvider()
                  playerGlue.play()
              }
          }
      })
      playerGlue.setSubtitle("Leanback artist")
      playerGlue.setTitle("Leanback team at work")
      val uriPath = "android.resource://com.example.android.leanback/raw/video"
      playerGlue.getPlayerAdapter().setDataSource(Uri.parse(uriPath))
  }
}

Java

public class MyVideoFragment extends VideoSupportFragment {

  @Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      final PlaybackTransportControlGlue<MediaPlayerAdapter> playerGlue =
              new PlaybackTransportControlGlue(getActivity(),
                      new MediaPlayerAdapter(getActivity()));
      playerGlue.setHost(new VideoSupportFragmentGlueHost(this));
      playerGlue.addPlayerCallback(new PlaybackGlue.PlayerCallback() {
          @Override
          public void onPreparedStateChanged(PlaybackGlue glue) {
              if (glue.isPrepared()) {
                  playerGlue.setSeekProvider(new MySeekProvider());
                  playerGlue.play();
              }
          }
      });
      playerGlue.setSubtitle("Leanback artist");
      playerGlue.setTitle("Leanback team at work");
      String uriPath = "android.resource://com.example.android.leanback/raw/video";
      playerGlue.getPlayerAdapter().setDataSource(Uri.parse(uriPath));
  }
}

請注意,設定程式碼也會定義 PlayerAdapter.Callback,用於處理媒體播放器的事件。

自訂 UI 黏膠

您可以自訂 PlaybackBannerControlGluePlaybackTransportControlGlue 來變更 PlaybackControlsRow

自訂標題和說明

如要自訂播放控制項頂端的標題和說明,請覆寫 onCreateRowPresenter()

Kotlin

override fun onCreateRowPresenter(): PlaybackRowPresenter {
    return super.onCreateRowPresenter().apply {
        (this as? PlaybackTransportRowPresenter)
                ?.setDescriptionPresenter(MyCustomDescriptionPresenter())
    }
}

Java

@Override
protected PlaybackRowPresenter onCreateRowPresenter() {
  PlaybackTransportRowPresenter presenter = (PlaybackTransportRowPresenter) super.onCreateRowPresenter();
  presenter.setDescriptionPresenter(new MyCustomDescriptionPresenter());
  return presenter;
}

新增控制項

控制黏膠會顯示 PlaybackControlsRow 中動作的控制項。

PlaybackControlsRow 中的動作會指派給兩個群組:「主要動作」和「次要動作」。主要群組的控制項會顯示在控制列上方,次要群組的控制項會顯示在搜尋列下方。一開始,播放/暫停按鈕只有一個主要動作,沒有次要動作。

您可以覆寫 onCreatePrimaryActions()onCreateSecondaryActions(),將動作新增至主要和次要群組。

Kotlin

private lateinit var repeatAction: PlaybackControlsRow.RepeatAction
private lateinit var pipAction: PlaybackControlsRow.PictureInPictureAction
private lateinit var thumbsUpAction: PlaybackControlsRow.ThumbsUpAction
private lateinit var thumbsDownAction: PlaybackControlsRow.ThumbsDownAction
private lateinit var skipPreviousAction: PlaybackControlsRow.SkipPreviousAction
private lateinit var skipNextAction: PlaybackControlsRow.SkipNextAction
private lateinit var fastForwardAction: PlaybackControlsRow.FastForwardAction
private lateinit var rewindAction: PlaybackControlsRow.RewindAction

override fun onCreatePrimaryActions(primaryActionsAdapter: ArrayObjectAdapter) {
    // Order matters, super.onCreatePrimaryActions() will create the play / pause action.
    // Will display as follows:
    // play/pause, previous, rewind, fast forward, next
    //   > /||      |<        <<        >>         >|
    super.onCreatePrimaryActions(primaryActionsAdapter)
    primaryActionsAdapter.apply {
        add(skipPreviousAction)
        add(rewindAction)
        add(fastForwardAction)
        add(skipNextAction)
    }
}

override fun onCreateSecondaryActions(adapter: ArrayObjectAdapter?) {
    super.onCreateSecondaryActions(adapter)
    adapter?.apply {
        add(thumbsDownAction)
        add(thumbsUpAction)
    }
}

Java

private PlaybackControlsRow.RepeatAction repeatAction;
private PlaybackControlsRow.PictureInPictureAction pipAction;
private PlaybackControlsRow.ThumbsUpAction thumbsUpAction;
private PlaybackControlsRow.ThumbsDownAction thumbsDownAction;
private PlaybackControlsRow.SkipPreviousAction skipPreviousAction;
private PlaybackControlsRow.SkipNextAction skipNextAction;
private PlaybackControlsRow.FastForwardAction fastForwardAction;
private PlaybackControlsRow.RewindAction rewindAction;

@Override
protected void onCreatePrimaryActions(ArrayObjectAdapter primaryActionsAdapter) {
    // Order matters, super.onCreatePrimaryActions() will create the play / pause action.
    // Will display as follows:
    // play/pause, previous, rewind, fast forward, next
    //   > /||      |<        <<        >>         >|
    super.onCreatePrimaryActions(primaryActionsAdapter);
    primaryActionsAdapter.add(skipPreviousAction);
    primaryActionsAdapter.add(rewindAction);
    primaryActionsAdapter.add(fastForwardAction);
    primaryActionsAdapter.add(skipNextAction);
}

@Override
protected void onCreateSecondaryActions(ArrayObjectAdapter adapter) {
    super.onCreateSecondaryActions(adapter);
    adapter.add(thumbsDownAction);
    adapter.add(thumbsUpAction);
}

您必須覆寫 onActionClicked() 來處理新動作。

Kotlin

override fun onActionClicked(action: Action) {
    when(action) {
        rewindAction -> {
            // Handle Rewind
        }
        fastForwardAction -> {
            // Handle FastForward
        }
        thumbsDownAction -> {
            // Handle ThumbsDown
        }
        thumbsUpAction -> {
            // Handle ThumbsUp
        }
        else ->
            // The superclass handles play/pause and delegates next/previous actions to abstract methods,
            // so those two methods should be overridden rather than handling the actions here.
            super.onActionClicked(action)
    }
}

override fun next() {
    // Skip to next item in playlist.
}

override fun previous() {
    // Skip to previous item in playlist.
}

Java

@Override
public void onActionClicked(Action action) {
    if (action == rewindAction) {
        // Handle Rewind
    } else if (action == fastForwardAction ) {
        // Handle FastForward
    } else if (action == thumbsDownAction) {
        // Handle ThumbsDown
    } else if (action == thumbsUpAction) {
        // Handle ThumbsUp
    } else {
        // The superclass handles play/pause and delegates next/previous actions to abstract methods,
        // so those two methods should be overridden rather than handling the actions here.
        super.onActionClicked(action);
    }
}

@Override
public void next() {
    // Skip to next item in playlist.
}

@Override
public void previous() {
    // Skip to previous item in playlist.
}

在特殊情況下,您可能會想要實作自己的 PlaybackTransportRowPresenter 以算繪自訂控制項,並使用 PlaybackSeekUi 回應跳轉動作。

影片拖曳

如果您的應用程式使用 VideoSupportFragment,而且您想支援影片拖曳功能。

刷洗

您必須提供 PlaybackSeekDataProvider 的實作方式。這個元件會提供捲動時要使用的影片縮圖。您必須擴充 PlaybackSeekDataProvider,自行實作提供者。請參閱 Android TV GitHub 存放區中的 Android Leanback 展示範例範例應用程式。.