build method
构建播放器视图
Builds the main player view.
Implementation
@override
Widget build(BuildContext context) {
  return PopScope(
    onPopInvoked: (bool didPop) {
      if (didPop) return; // 如果已经处理了返回操作,则直接返回
      _handleBackPress();
    },
    child: _buildContentBody(),
  );
}