允許使用者變更註解追蹤

此程式範例說明如何建立可讓使用者選取隱藏式字幕追蹤的按鈕。

1. 建立按鈕以變更隱藏式字幕追蹤。

   <Button
     android:id="@+id/selectCC"
     android:layout_width="wrap_content"
     android:layout_height="wrap_content"
     android:layout_alignParentBottom="true"
     android:layout_alignParentRight="true"
     android:layout_marginRight="10dp"
     android:onClick="selectClosedCaptioningClick"
     android:text="CC" />
   

2. 將可用的隱藏式字幕曲目清單轉換為字串陣列。

   隱藏式字幕追蹤具有活動（即TVSDK已探索資料的管道），並會適當地標示。

   /**
   * Converts the closed captions tracks to a string array.
   *
   * @return array of CC tracks
   */
   private String[] getCCsAsArray() {
       List<String> closedCaptionsTracksAsStrings = new ArrayList<String>();
       MediaPlayerItem currentItem = mediaPlayer.getCurrentItem();
       if (currentItem != null) {
           List<ClosedCaptionsTrack> closedCaptionsTracks =
           currentItem.getClosedCaptionsTracks();
           Iterator<ClosedCaptionsTrack> iterator = closedCaptionsTracks.iterator();
           while (iterator.hasNext()) {
               ClosedCaptionsTrack closedCaptionsTrack = iterator.next();
               String isActive = closedCaptionsTrack.isActive() ? " (" +
                 getString(R.string.active)+ ")" : "";
               closedCaptionsTracksAsStrings.add(closedCaptionsTrack.getName() +
                 isActive);
           }
       }
       return closedCaptionsTracksAsStrings.
         toArray(new String[closedCaptionsTracksAsStrings.size()]);
   }
   

3. 當使用者按一下按鈕時，顯示列出所有預設隱藏式字幕追蹤的對話方塊。

   public void selectClosedCaptioningClick(View view) {
       Log.i(LOG_TAG + "#selectClosedCaptions", "Displaying closed captions chooser dialog.");
       final String items[] = getCCsAsArray();
       final AlertDialog.Builder ab = new AlertDialog.Builder(this);
       ab.setTitle(R.string.PlayerControlCCDialogTitle);
       ab.setSingleChoiceItems(items, selectedClosedCaptionsIndex, new DialogInterface.OnClickListener() {
           public void onClick(DialogInterface dialog, int whichButton) {
               // Select the new closed captioning track.
               MediaPlayerItem currentItem = mediaPlayer.getCurrentItem();
               ClosedCaptionsTrack desiredClosedCaptionsTrack =
                 currentItem.getClosedCaptionsTracks().get(whichButton);
               boolean result = currentItem.selectClosedCaptionsTrack(desiredClosedCaptionsTrack);
               if (result) {
                   selectedClosedCaptionsIndex = whichButton;
               }
               // Dismiss dialog.
               dialog.cancel();
        }
       }).setNegativeButton(R.string.PlayerControlCCDialogCancel, new DialogInterface.OnClickListener() {
           public void onClick(DialogInterface dialog, int whichButton) {
               // Just cancel the dialog.
           }
       });
       ab.show();
   }