I think this is definitely a bug

[sunshaobei]

layout : ViewPage2 or RecyclerView bind a itemView witch is ConstraintLayout with a child , and this child set paddingStart or paddingEnd,

first: I set the ConstraintLayout‘visibility Gone

second : when the view created i set ConstraintLayout‘visibility visible

then I found the child can not show

[sunshaobei]

this is my code

 class MainActivity : AppCompatActivity() {
    val adapter = MyAdapter(this)
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        findViewById<ViewPager2>(R.id.vp).adapter = adapter
    }
}

---

  class MyAdapter(activity: MainActivity) : FragmentStateAdapter(activity) {

    override fun getItemCount(): Int {
      return 1
    }

    override fun createFragment(position: Int): Fragment {
        return MainFragment()
    }
}

------------------------------------------------------- activity_main.layout

  <?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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <androidx.viewpager2.widget.ViewPager2
        android:id="@+id/vp"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>
</androidx.constraintlayout.widget.ConstraintLayout>

---

/**
 * @author sunshaobei on 2023/8/4
 */
   class MainFragment:Fragment() {
    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        val dataBinding:FragmentMainBinding = DataBindingUtil.inflate(inflater,R.layout.fragment_main,container,false)
        dataBinding.testBtn.setOnClickListener {
            val value = dataBinding.tv.isLayoutRequested
            dataBinding.cl.isVisible = !dataBinding.cl.isVisible
        }
        return dataBinding.root
    }
}

------------------------------------------------------- fragment_main.layout

 <?xml version="1.0" encoding="utf-8"?>
 <layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <data>

    </data>

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">
 
        <androidx.constraintlayout.widget.ConstraintLayout
            android:id="@+id/cl"
            android:layout_width="match_parent"
            android:layout_height="30dp"
            android:visibility="gone"
            android:layout_gravity="center">

            <View
                android:id="@+id/tv"
                android:layout_width="60dp"
                android:layout_height="match_parent"
                android:background="#ff0000"
                android:gravity="center"
                android:paddingStart="6dp"
                android:textSize="13sp"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toTopOf="parent" />


        </androidx.constraintlayout.widget.ConstraintLayout>


        <Button
            android:id="@+id/test_btn"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:onClick="show"
            android:text="显示"
            android:layout_gravity="center_horizontal|bottom" />

    </FrameLayout>
</layout>

[sunshaobei]

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <data>

    </data>

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">
       
        <LinearLayout
            android:id="@+id/cl"
            android:layout_width="match_parent"
            android:layout_height="30dp"
            android:visibility="gone"
            android:layout_gravity="center">

            <View
                android:id="@+id/tv"
                android:layout_width="60dp"
                android:layout_height="match_parent"
                android:background="#ff0000"
                android:gravity="center"
                android:paddingStart="6dp"
                android:textSize="13sp"
            />

        </LinearLayout>


        <Button
            android:id="@+id/test_btn"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:onClick="show"
            android:text="显示"
            android:layout_gravity="center_horizontal|bottom" />

    </FrameLayout>
</layout>

if i change the ContraintLayout to other viewgroup , that will be fine, or i delete the paddingStart of contraintlayout's child that will be fine too

[sunshaobei]

or i just remove the viewpager2(recyclerview) that will be fine

[sunshaobei]

i have no idear about this problem , and i have read a lot of source code of View、constraintlayout and recyclerview , then i found nothing

[sunshaobei]

So, can you determine if this problem is ConstraintLayout‘s problem??? or recyclerview‘s

[sunshaobei]

In this case , i found recyclerView+ConstraintString with RTL set like paddingStrat will be making this problem ,i fix this problem with a custom ConstraintLayout witch override it's addview(function) and add getPaddingStart() code only