在 xamarin.android 中管理屏幕旋转时的片段外观

Posted 2023-04-18

【中文标题】在 xamarin.android 中管理屏幕旋转时的片段外观

【英文标题】：manage fragment appearance upon screen rotation in xamarin.android

【发布时间】：2020-12-11 05:16:06

【问题描述】：

当我以为我终于完成了我的 android 应用程序后，我发现当我的手机屏幕旋转时，我的应用程序崩溃了。所以在做了一些研究之后，我发现我必须将这一行添加到我的活动中：

[Activity(Label = "FreeLineApp", Theme = "@style/AppTheme.NoActionBar", MainLauncher = true, NoHistory = true, ConfigurationChanges = Android.Content.PM.ConfigChanges.Orientation | Android.Content.PM.ConfigChanges.ScreenSize)]

这行得通，但并不完全。事实上，我的应用程序有一个登录片段，一旦我启动应用程序就会出现。此片段显示在登录活动中，该活动设置为具有空布局的主启动器。当手机屏幕旋转时，这个登录片段不会完全出现。就像它被裁剪一样。 这是我的片段的登录 xml：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_
    android:layout_
    android:background="@android:color/white"
    android:gravity="center"
    android:minHeight="1500px"
    android:minWidth="1000px"
   
    >
    <TextView
        android:text="Welcome to FreeLineApp!"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:layout_
        android:layout_
        android:id="@+id/textView1" 
    android:layout_marginBottom="40dp"
    android:textAlignment="center"
    android:textColor="@android:color/holo_blue_dark"/>
        <EditText
        android:layout_
        android:hint="Account"
        android:id="@+id/editText1"
    android:background="@drawable/logincustom"
    android:layout_
     android:layout_marginLeft="10dp"
    android:layout_marginRight="10dp"/>
     <EditText
        android:layout_
        android:hint="Password"
        android:id="@+id/editText2"
    android:layout_marginTop="20dp"
    android:layout_
    android:background="@drawable/logincustom"
    android:layout_marginLeft="10dp"
    android:layout_marginRight="10dp"/>
    <Button
        android:layout_
        android:layout_
        android:id="@+id/button1"
        android:text="Login"
         android:layout_marginTop="30dp"
        android:background="@drawable/buttoncustom"
    />
    <RelativeLayout
        android:layout_
        android:layout_
        android:layout_marginTop="20dp"
        android:gravity="center">
<CheckBox
    android:layout_
    android:layout_
        android:id="@+id/checkBox1"/>
        <TextView
            android:text="Keep me logged in"
            android:layout_
            android:layout_
            android:id="@+id/textView2" 
        android:layout_toRightOf="@+id/checkBox1"
            android:layout_marginRight="20dp"
            android:textColor="@android:color/holo_blue_dark"
            android:layout_marginTop="6dp"
        />
    
</RelativeLayout>
</LinearLayout>

这是片段出现的我的登录活动：

 [Activity(Label = "FreeLineApp", Theme = "@style/AppTheme.NoActionBar", MainLauncher = true, NoHistory = true, ConfigurationChanges = Android.Content.PM.ConfigChanges.Orientation | Android.Content.PM.ConfigChanges.ScreenSize)]
    public class LoginActivity : AppCompatActivity,OnLoginInforCompleted
    
        private AlertDialog _dialog;
        ISharedPreferences pref = Application.Context.GetSharedPreferences("UserInfo", FileCreationMode.Private);
        public void inputLoginInforCompleted(string userName, string passWord)
        
            appuser app_user = new appuser()
            

                UserName = user.Username,
                Password = user.Password
            ;
            Intent intent = new Intent(this, typeof(MainActivity));
            intent.PutExtra("User", JsonConvert.SerializeObject(app_user));
            this.StartActivity(intent);
            //throw new NotImplementedException();
            StartActivity(new Intent(this, typeof(MainActivity)));
        

        protected override void OnCreate(Bundle savedInstanceState)
        
            base.OnCreate(savedInstanceState);
            SetContentView(Resource.Layout.layout1);
            //  StartActivity(typeof(MainActivity));
            var current = Connectivity.NetworkAccess;

            if (current == NetworkAccess.Internet)
            
                string userName = pref.GetString("Username", String.Empty);
                string password = pref.GetString("Password", String.Empty);
                if (userName == String.Empty || password == String.Empty)
                
                    MyDialogFragment dialogFragment = new MyDialogFragment();
                    dialogFragment.setOnLoginInforCompleted(this);

                    dialogFragment.Cancelable = false;
                    var SupportFragmentManager = this.FragmentManager;
                    dialogFragment.Show(SupportFragmentManager, "dialog");
                

                else
                
                    Intent intent = new Intent(this, typeof(MainActivity));
                   
                    appuser app_user = new appuser()
                    
                       
                        UserName = user.Username,
                        Password = user.Password
                    ;

                    intent.PutExtra("User", JsonConvert.SerializeObject(app_user));
                    this.StartActivity(intent);
                

            
            else
            
                

                AlertDialog.Builder alert = new AlertDialog.Builder(this);

                alert.SetTitle("Connection failed");

                alert.SetMessage("Please, check your internet Connection!");
                alert.SetNeutralButton("okay", (senderAlert, args) => 

                    alert.Dispose();
                    MyDialogFragment dialogFragment = new MyDialogFragment();
                    dialogFragment.setOnLoginInforCompleted(this);

                    dialogFragment.Cancelable = false;
                    var SupportFragmentManager = this.FragmentManager;
                    dialogFragment.Show(SupportFragmentManager, "dialog");

                );
                _dialog = alert.Create();

                _dialog.Show();
            
            // Create your application here
        

       
    

以下图片是手机屏幕旋转时发生的情况：

我该怎么办？

【参考方案1】：

您可以创建两种布局，一种用于Portrait，另一种用于Landscape。然后当屏幕旋转时，它会显示为你想要的。

例如，Layout文件夹如下：

并从Activity中删除ConfigurationChanges = Android.Content.PM.ConfigChanges.Orientation | Android.Content.PM.ConfigChanges.ScreenSize。

那么当手机屏幕旋转时布局会发生变化。