Question

当用户点击操作栏中的某个项目时，我正在尝试向活动添加一个片段，但是我无法将其显示出来。这是主要的代码没有按照我期望的方式工作（这是用Monodroid编写的）：

public override bool OnOptionsItemSelected(IMenuItem item)
    {
      if (item.ItemId == Resource.Id.show_hide_notes)
      {
        notesLayout.Visibility = ViewStates.Visible;

        notesWebViewFragment = new NotesWebViewFragment();
        // linearLayout.LayoutParameters = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.FillParent, LinearLayout.LayoutParams.WrapContent, 1);

        Android.Support.V4.App.FragmentTransaction fragmentTransaction = SupportFragmentManager.BeginTransaction();
        fragmentTransaction.Add(Resource.Id.notes_fragment_container, notesWebViewFragment);
        fragmentTransaction.Commit();

        // Adding this line doesn't help
        // FindViewById<LinearLayout>(Resource.Id.plex_frame_container).Invalidate();
      }
      return true;
    }

当我用OnCreate方法中的另一个片段添加这个片段时，我得到了我的期望。我尝试了几种不同的方法来试图让它显示出来。任何解释我做错了什么将非常感激。我在下面添加了其余的相关代码。

 [Activity]
  public class BrainViewActivity : Android.Support.V4.App.FragmentActivity
  {
    private Brain activeBrain;

    PlexWebViewFragment plexWebViewFragment;
    NotesWebViewFragment notesWebViewFragment;

    FrameLayout notesLayout;

    protected override void OnCreate(Bundle savedInstanceState)
    {
      base.OnCreate(savedInstanceState);

      SetContentView(Resource.Layout.brain_view);

      notesLayout = FindViewById<FrameLayout>(Resource.Id.notes_fragment_container);
      // notesLinearLayout.LayoutParameters = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.FillParent, LinearLayout.LayoutParams.WrapContent, 0);
      notesLayout.Visibility = ViewStates.Gone;

      if (savedInstanceState == null)
      {
        // Create an instance of PlexWebViewFragment
        plexWebViewFragment = new PlexWebViewFragment();
      }

      // Check that the activity is using the layout version with
      // the fragment_container FrameLayout
      if (FindViewById(Resource.Id.plex_fragment_container) != null)
      {
        plexWebViewFragment.Arguments = Intent.Extras;

        Android.Support.V4.App.FragmentTransaction fragmentTransaction = SupportFragmentManager.BeginTransaction();
        fragmentTransaction.Add(Resource.Id.plex_fragment_container, plexWebViewFragment);

        fragmentTransaction.Commit();
      }
    }

    public override bool OnCreateOptionsMenu(IMenu menu)
    {
      base.OnCreateOptionsMenu(menu);
      MenuInflater.Inflate(Resource.Menu.brain_view_menu, menu);

      return true;
    }

    public override bool OnOptionsItemSelected(IMenuItem item)
    {
      if (item.ItemId == Resource.Id.show_hide_notes)
      {
        notesLayout.Visibility = ViewStates.Visible;

        notesWebViewFragment = new NotesWebViewFragment();
        // linearLayout.LayoutParameters = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.FillParent, LinearLayout.LayoutParams.WrapContent, 1);

        Android.Support.V4.App.FragmentTransaction fragmentTransaction = SupportFragmentManager.BeginTransaction();
        fragmentTransaction.Add(Resource.Id.notes_fragment_container, notesWebViewFragment);
        fragmentTransaction.Commit();

        // Adding this line doesn't help
        // FindViewById<LinearLayout>(Resource.Id.plex_frame_container).Invalidate();
      }
      return true;
    }
  }

xml视图：

<?xml version="1.0" encoding="utf-8" ?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:id="@+id/plex_frame_container"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:orientation="vertical">
  <FrameLayout
    android:id="@+id/plex_fragment_container"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_weight="1"/>

  <FrameLayout
    android:id="@+id/notes_fragment_container"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_weight="1"/>
</LinearLayout>

如果我立即添加片段，这又有效，否则当我尝试稍后添加它时，活动视图永远不会改变以显示片段。几乎就像我需要告诉活动重新粉刷？任何帮助，将不胜感激。提前谢谢。

Answer 1

如果我帮助其他人，我会弄清楚问题是什么。添加新片段后，我需要让Activity重新布局。根据我的搜索，我看到关于调用invalidate的评论如下：

FindViewById<LinearLayout>(Resource.Id.plex_frame_container).Invalidate();

然而，这是不正确的（至少在我的情况下），并没有让它调整大小（或更正确地重新布局）视图。但是，调用RequestLayout正是我所需要的，并且片段开始显示。例如：

FindViewById<LinearLayout>(Resource.Id.plex_frame_container).RequestLayout();

希望这有帮助。

初始布局设置未显示后，将片段添加到活动

1 个答案: