ConstraintLayout, when constraint dependent view is gone, the layout view behave weirdly

Question

I'm using ConstraintLayout where I will show as below

I would like to hide First (using gone), and which the view I expect to be as below (where ElasticBody will stretch over to use up the original First view space as well.

However, when I actual set First to gone, my view turn out to be as below (all image as from Android Studio Design view). My Elastic Body is missing as well, and the height expanded weirdly.

My layout code as below

<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"
    android:padding="16dp">

    <TextView
        android:id="@+id/txt_first"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="#0ff"
        android:text="First"
        android:visibility="gone"
        android:textSize="26sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toStartOf="@+id/txt_body"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/txt_body"
        android:layout_width="0dp"
        android:background="#f0f"
        android:layout_height="wrap_content"
        android:text="Elastic Body"
        android:textSize="26sp"

        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toStartOf="@+id/txt_tail"
        app:layout_constraintStart_toEndOf="@+id/txt_first"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/txt_tail"
        android:background="#ff0"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Tail"
        android:textSize="26sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@+id/txt_body"
        app:layout_constraintTop_toTopOf="parent" />

</android.support.constraint.ConstraintLayout>

(Note, if you remove the gone, you'll get the first image view). Why is this so? How could I fix it where when my First is gone, I could the Elastic Body stretch out correctly?

p/s: I know how to do it in LinearLayout and RelativeLayout... but wonder if this is a limitation on ConstraintLayout?

Answer 1

Try following.

Set the first view's left and top constraints to "parent". After that:

• set the txt_body textview width to "0dp"
• set the left constraint to the first view's right side
• set the right constraint to the tail view's left side.

So, whenever you set the first view's visibility to "gone", the body view will be stretched like how you want it.

<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"
    android:padding="16dp">

    <TextView
        android:id="@+id/txt_first"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="#0ff"
        android:text="First"
        android:textSize="26sp"
        android:visibility="gone"
        app:layout_constraintEnd_toStartOf="@+id/txt_body"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintLeft_toLeftOf="parent" />

    <TextView
        android:id="@+id/txt_body"
        android:layout_width="0dp"
        android:background="#f0f"
        android:layout_height="wrap_content"
        android:text="Elastic Body"
        android:textSize="26sp"
        app:layout_constraintRight_toLeftOf="@+id/txt_tail"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintLeft_toRightOf="@+id/txt_first"
        />

    <TextView
        android:id="@+id/txt_tail"
        android:background="#ff0"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Tail"
        android:textSize="26sp"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintRight_toRightOf="parent" />

</android.support.constraint.ConstraintLayout>

Update

If you want to do using barrier then also you can do it.

<androidx.constraintlayout.widget.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"
    android:padding="16dp">

    <TextView
        android:id="@+id/txt_first"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="#0ff"
        android:text="First"
        android:textSize="26sp"
        android:visibility="gone"
        app:layout_constraintEnd_toStartOf="@+id/barrier"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/txt_body"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:background="#f0f"
        android:text="Elastic Body"
        android:textSize="26sp"
        app:layout_constraintStart_toEndOf="@+id/barrier"
        app:layout_constraintEnd_toStartOf="@+id/txt_tail"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/txt_tail"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="#ff0"
        android:text="Tail"
        android:textSize="26sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <androidx.constraintlayout.widget.Barrier
        android:id="@+id/barrier"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:barrierDirection="start"
        app:constraint_referenced_ids="txt_body,txt_first" />

    <androidx.constraintlayout.widget.Barrier
        android:id="@+id/barrier1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:barrierDirection="end"
        app:constraint_referenced_ids="txt_body,txt_tail" />

</androidx.constraintlayout.widget.ConstraintLayout>