ConstraintSet を使って Activity を再生成せずにレイアウトを切り替える

自分で縦横レイアウトを切り替えるので Manifest に設定を追加

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1. <activity  
2.     android:name=".MainActivity"  
3.     android:configChanges="orientation|screenSize|screenLayout|keyboardHidden">  
4.   
5.     ...  
6.   
7. </activity>  

<activity android:name=".MainActivity" android:configChanges="orientation|screenSize|screenLayout|keyboardHidden"> ... </activity> 縦画面用のレイアウトと、横画面用のレイアウトを用意する。
例としてここでは縦画面では上部に 16:9 で配置し、横画面では全画面に配置している。

縦画面用
res/layout/activity_main_port.xml

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1. <?xml version="1.0" encoding="utf-8"?>  
2. <androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"  
3.     xmlns:app="http://schemas.android.com/apk/res-auto"  
4.     xmlns:tools="http://schemas.android.com/tools"  
5.     android:id="@+id/constraintLayout"  
6.     android:layout_width="match_parent"  
7.     android:layout_height="match_parent"  
8.     tools:context=".MainActivity">  
9.   
10.     <include  
11.         android:id="@+id/container"  
12.         layout="@layout/activity_main"  
13.         android:layout_width="0dp"  
14.         android:layout_height="0dp"  
15.         app:layout_constraintDimensionRatio="16:9"  
16.         app:layout_constraintEnd_toEndOf="parent"  
17.         app:layout_constraintStart_toStartOf="parent"  
18.         app:layout_constraintTop_toTopOf="parent" />  
19.   
20. </androidx.constraintlayout.widget.ConstraintLayout>  

<?xml version="1.0" encoding="utf-8"?> <androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/constraintLayout" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity"> <include android:id="@+id/container" layout="@layout/activity_main" android:layout_width="0dp" android:layout_height="0dp" app:layout_constraintDimensionRatio="16:9" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent" /> </androidx.constraintlayout.widget.ConstraintLayout> 横画面用
res/layout/activity_main_land.xml

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1. <?xml version="1.0" encoding="utf-8"?>  
2. <androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"  
3.     xmlns:app="http://schemas.android.com/apk/res-auto"  
4.     xmlns:tools="http://schemas.android.com/tools"  
5.     android:id="@+id/constraintLayout"  
6.     android:layout_width="match_parent"  
7.     android:layout_height="match_parent"  
8.     tools:context=".MainActivity">  
9.   
10.     <include  
11.         android:id="@+id/container"  
12.         layout="@layout/activity_main"  
13.         android:layout_width="0dp"  
14.         android:layout_height="0dp"  
15.         app:layout_constraintBottom_toBottomOf="parent"  
16.         app:layout_constraintEnd_toEndOf="parent"  
17.         app:layout_constraintStart_toStartOf="parent"  
18.         app:layout_constraintTop_toTopOf="parent" />  
19.   
20. </androidx.constraintlayout.widget.ConstraintLayout>  

<?xml version="1.0" encoding="utf-8"?> <androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/constraintLayout" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity"> <include android:id="@+id/container" layout="@layout/activity_main" android:layout_width="0dp" android:layout_height="0dp" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent" /> </androidx.constraintlayout.widget.ConstraintLayout> activity_main_port.xml と activity_main_land.xml からそれぞれ ConstraintSet を構成する。
onConfigurationChanged() で画面の向きに応じて対応する ConstraintSet を ConstraintLayout に applyTo() する。

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1. class MainActivity : AppCompatActivity() {  
2.   
3.     private val constraintSetPort = ConstraintSet()  
4.     private val constraintSetLand = ConstraintSet()  
5.   
6.     private lateinit var constraintLayout: ConstraintLayout  
7.   
8.     override fun onCreate(savedInstanceState: Bundle?) {  
9.         super.onCreate(savedInstanceState)  
10.         val layoutId = when (resources.configuration.orientation) {  
11.             Configuration.ORIENTATION_LANDSCAPE -> R.layout.activity_main_land  
12.             else -> R.layout.activity_main_port  
13.         }  
14.         setContentView(layoutId)  
15.         constraintLayout = findViewById(R.id.constraintLayout)  
16.   
17.         constraintSetPort.clone(this, R.layout.activity_main_port)  
18.         constraintSetLand.clone(this, R.layout.activity_main_land)  
19.     }  
20.   
21.     override fun onConfigurationChanged(newConfig: Configuration) {  
22.         super.onConfigurationChanged(newConfig)  
23.   
24.         val constraintSet = when (newConfig.orientation) {  
25.             Configuration.ORIENTATION_LANDSCAPE -> constraintSetLand  
26.             else -> constraintSetPort  
27.         }  
28.         constraintSet.applyTo(constraintLayout)  
29.     }  
30. }  

class MainActivity : AppCompatActivity() { private val constraintSetPort = ConstraintSet() private val constraintSetLand = ConstraintSet() private lateinit var constraintLayout: ConstraintLayout override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) val layoutId = when (resources.configuration.orientation) { Configuration.ORIENTATION_LANDSCAPE -> R.layout.activity_main_land else -> R.layout.activity_main_port } setContentView(layoutId) constraintLayout = findViewById(R.id.constraintLayout) constraintSetPort.clone(this, R.layout.activity_main_port) constraintSetLand.clone(this, R.layout.activity_main_land) } override fun onConfigurationChanged(newConfig: Configuration) { super.onConfigurationChanged(newConfig) val constraintSet = when (newConfig.orientation) { Configuration.ORIENTATION_LANDSCAPE -> constraintSetLand else -> constraintSetPort } constraintSet.applyTo(constraintLayout) } }