ConstraintLayout Barrier not working properly when parent dimensions are set to wrap_content

Question

Here's a reproduction of my issue:

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    
    <TextView
        android:id="@+id/textView"
        android:layout_width="0dp"
        android:layout_height="wrap_content" 
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintEnd_toStartOf="@id/textView2"
        android:text="Text"/>
    
    <TextView
        android:id="@+id/textView2"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        app:layout_constraintStart_toEndOf="@id/textView"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        android:layout_marginStart="16dp"
        android:text="muchlongertextmuchlongertextmuchlongertextmuchlongertextmuchlongertextmuchlongertextmuchlongertextmuchlongertextmuchlongertextmuchlongertextmuchlongertext"/>
    
    <android.support.constraint.Barrier
        android:id="@+id/barrier"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" 
        app:barrierDirection="bottom"
        app:constraint_referenced_ids="textView, textView2"/>
    
    <TextView
        android:id="@+id/textView3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:layout_constraintTop_toBottomOf="@id/barrier"
        android:text="muchlongertextmuchlongertextmuchlongertextmuchlongertextmuchlongertextmuchlongertextmuchlongertextmuchlongertextmuchlongertextmuchlongertextmuchlongertext"/>
    
</android.support.constraint.ConstraintLayout>

When you set the parent height to match_parent, the Barrier works as intended. But, as soon as you set it to wrap_content, it doesn't do the layout properly.

Here's how it looks with wrap_content, and at the right with match_parent:

If anyone could point me in the right direction it would be much appreciated. I didn't find anyone advocating against using Barriers this way, but didn't find anyone who got that kind of layout working.

Is that a mistake on my part or is that a bug in Barrier?

Answer 1

It is not clear what you mean by "parent". If I set the height of the ConstraintLayout (the only parent I can see) to match_parent, nothing changes. The result is as your first picture.

What you have to do, to make the barrier hold back the bottom textView3 is to complete the vertical chain between textView, textView2 and barrier. The code will then look like this:

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <TextView
        android:id="@+id/textView"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:text="Text"
        app:layout_constraintBottom_toTopOf="@id/barrier"
        app:layout_constraintEnd_toStartOf="@id/textView2"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/textView2"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:text="muchlongertextmuchlongertextmuchlongertextmuchlongertextmuchlongertextmuchlongertextmuchlongertextmuchlongertextmuchlongertextmuchlongertextmuchlongertext"
        app:layout_constraintBottom_toTopOf="@id/barrier"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@id/textView"
        app:layout_constraintTop_toTopOf="parent" />

    <android.support.constraint.Barrier
        android:id="@+id/barrier"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:barrierDirection="bottom"
        app:constraint_referenced_ids="textView, textView2" />

    <TextView
        android:id="@+id/textView3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="muchlongertextmuchlongertextmuchlongertextmuchlongertextmuchlongertextmuchlongertextmuchlongertextmuchlongertextmuchlongertextmuchlongertextmuchlongertext"
        app:layout_constraintTop_toBottomOf="@id/barrier" />

</android.support.constraint.ConstraintLayout>