Question

我很确定这是一个Android问题; Xamarin部分只是偶然的。

我有一个简单的基于TabLayout的Xamarin.Android应用程序。它基于Xamarin的SupportLibFragments sample，但我添加了一个TabLayout。我想知道如何处理屏幕方向的变化。现在，如果您更改屏幕方向，应用程序根本不会做出反应。我甚至不知道从哪里开始。我将在下面发布关键代码，整个项目可用on Github。

以下是一些关键文件。首先，activity_main.axml：

<LinearLayout 
  xmlns:android="http://schemas.android.com/apk/res/android"

      xmlns:app="http://schemas.android.com/apk/res-auto"
  android:id="@+id/main_layout"
        android:orientation="vertical"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent">
    <android.support.design.widget.TabLayout
        android:id="@+id/tab_layout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:tabMode="fixed"
        app:tabGravity="fill"
        android:theme="@style/Theme.TabBar"/>
    <android.support.v4.view.ViewPager
        android:id="@+id/viewpager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@android:color/white" />
</LinearLayout>

接下来，MainTabActivity.cs：

using Android.App;
using Android.OS;
using Android.Support.Design.Widget;
using Android.Support.V4.App;
using Android.Support.V4.View;

namespace com.xamarin.sample.fragments.supportlib
{
    [Activity(Label = "Fragments Walkthrough", MainLauncher = true, Icon = "@drawable/icon")]
    public class MainActivity : FragmentActivity
    {
        private TabLayout TabLayout => FindViewById<TabLayout>(Resource.Id.tab_layout);
        private ViewPager ViewPager => FindViewById<ViewPager>(Resource.Id.viewpager);

        protected override void OnCreate (Bundle bundle)
        {
            base.OnCreate (bundle);
            SetContentView (Resource.Layout.activity_main);
            var manager = SupportFragmentManager;
            var adapter = new DetailsAdapter(manager);
            ViewPager.Adapter = adapter;
            TabLayout.SetupWithViewPager(ViewPager);
            adapter.RefreshPageTitles(TabLayout);
        }
    }
}

接下来，DetailsAdapter.cs：

using Android.Support.Design.Widget;
using Android.Support.V4.App;
using Java.Lang;
using System.Linq;

namespace com.xamarin.sample.fragments.supportlib
{
    public class DetailsAdapter: FragmentPagerAdapter {
        public DetailsAdapter(FragmentManager manager): base(manager) {
    }

        public override int Count => Shakespeare.Titles.Count(); // Shakespeare is effectively the model class for the app. It contains a bunch of titles and associated text.

        public override Fragment GetItem(int position) {
            return DetailsFragment.NewInstance(position);
        }

        public override ICharSequence GetPageTitleFormatted(int position) {
            var str = position.ToString();
            return new Java.Lang.String(str);
        }

        internal void RefreshPageTitles(TabLayout tabLayout) {
            for (int i = 0; i < Count; i++) {
                var tab = tabLayout.GetTabAt(i);
                if (tab!=null) {
                    tab.SetText( GetPageTitleFormatted(i));
                }
            }
        }
    }
}

最后，DetailsFragment.cs：

using Android.OS;
using Android.Support.V4.App;
using Android.Views;
using Android.Widget;

namespace com.xamarin.sample.fragments.supportlib
{
    internal class DetailsFragment : Fragment
    {
        public static DetailsFragment NewInstance(int playId)
        {
            var detailsFrag = new DetailsFragment {Arguments = new Bundle()};
            detailsFrag.Arguments.PutInt("current_play_id", playId);
            return detailsFrag;
        }

        public int ShownPlayId
        {
            get { return Arguments.GetInt("current_play_id", 0); }
        }

        public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
        {
            if (container == null)
            {
                return null;
            }
            var inflatedView = new FrameLayout(this.Activity);
            inflatedView.SetBackgroundColor(Android.Graphics.Color.Orange);
            var text = new TextView(this.Context);
            inflatedView.AddView(text);
            var padding = 10;
            text.SetPadding(padding, padding, padding, padding);
            text.TextSize = 24;
            text.Text = Shakespeare.Dialogue[ShownPlayId]; // just returns a bunch of text

            return inflatedView;
        }
    }
}

编辑：我尝试在清单中启用旋转，如下所示，并删除MainActivity类上的属性。它没有帮助;当我旋转手机时，我的活动中没有调用OnDestroy。

 <?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" android:installLocation="auto">
    <application android:icon="@drawable/icon">
    <activity
      android:name="com.xamarin.sample.fragments.supportlib.MainActivity"
      android:label="Fragments Walkthrough"
      android:icon="@drawable/icon"
      android:configChanges="orientation|screenSize">
      <intent-filter>
        <action android:name="android.intent.action.MAIN"/>
        <category android:name="android.intent.category.LAUNCHER"/>
      </intent-filter>
    </activity>
  </application>
    <uses-sdk android:minSdkVersion="21" android:targetSdkVersion="27" />
</manifest>

Answer 1

我尝试了该应用程序，然后旋转了该程序，并在2个模拟器（Nexus 5，通用Android 7）和2个物理设备（Samsung S7 Edge和Oneplus One）上进行了测试

仔细检查系统旋转设置！

在基于TabLayout的应用程序上实现屏幕旋转

1 个答案: