Setting max height for only one ConstraintLayout chain view

Question

I have two views in a vertical chain in ConstraintLayout with spread_inside chain style. I want to set a max height using layout_constraintHeight_max for the first view only, but since it's the head of the chain it applies to all chained views.

How do I only apply a max height constraint to the first view of the chain?

Answer 1

That behavior of layout_constraintHeight_max is counter-intuitive. Try the following layout that should simulate a chain without the annoying layout_constraintHeight_max behavior. It uses a barrier to mark the top of the bottom view.

<androidx.constraintlayout.widget.ConstraintLayout 
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:id="@+id/topView"
        android:layout_width="200dp"
        android:layout_height="0dp"
        android:background="@android:color/holo_blue_light"
        app:layout_constraintBottom_toTopOf="@id/barrier"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHeight_max="200dp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        tools:text="This is the top view." />

    <TextView
        android:id="@+id/bottomView"
        android:layout_width="200dp"
        android:layout_height="0dp"
        android:background="@android:color/holo_red_light"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHeight_min="100dp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@id/topView"
        tools:text="This is the bottom view." />

    <androidx.constraintlayout.widget.Barrier
        android:id="@+id/barrier"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:barrierDirection="top"
        app:constraint_referenced_ids="bottomView" />
</androidx.constraintlayout.widget.ConstraintLayout>

You say that the top view can shrink down to 0dp. If you mean zero height, then the foregoing may not go that far by itself.