ConstraintLayout: Realign baseline constraint in case if dependent view visibility was set to GONE

Question

Is there any way to realign baseline constraint for the TextView in case if dependent view visibility was set to GONE?

My layout code:

<android.support.constraint.ConstraintLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <TextView
        android:id="@+id/title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="TEST TITLE"
        android:textColor="@color/black"
        android:textSize="24sp"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"/>

    <TextView
        android:id="@+id/subtitle1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="SUBTITLE 1"
        android:textSize="11sp"
        app:layout_constraintBaseline_toBaselineOf="@+id/subtitle2"
        app:layout_constraintHorizontal_chainStyle="packed"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toLeftOf="@+id/subtitleSpace"
        app:layout_constraintRight_toRightOf="parent"/>

    <android.support.v4.widget.Space
        android:id="@+id/subtitleSpace"
        android:layout_width="12dp"
        android:layout_height="wrap_content"
        app:layout_constraintLeft_toRightOf="@+id/subtitle1"
        app:layout_constraintRight_toLeftOf="@+id/subtitle2"/>

    <TextView
        android:id="@+id/subtitle2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="4dp"
        android:text="SUBTITLE 2"
        android:textSize="14sp"
        app:layout_constraintLeft_toRightOf="@+id/subtitleSpace"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/title"/>

</android.support.constraint.ConstraintLayout>

In this case, my layout looks like this:

When I'm setting subtitle2 TextView visibility to GONE my layout will look like this:

So I'm wondering if there is some constraint which can realign baseline in the case if the dependent view is missing.

Answer 1

Alternate margins can be specified for GONE widgets (see Margins when connected to a GONE widget), but I am not aware of such an alternative for baselines.

One way to satisfy your requirement is to specify a 0dp invisible TextView that has the same characterisics of the GONE TextView that is placed next to that same view. subtitle1 and subtitle2 would tie to the baseline of this new TextView. Even though the new TextView doesn't show on the screen and takes zero width, it still maintains a baseline.

Now, when subtitle2 is made GONE, subtitle1 will move to the center but maintain its vertical position. (Specifying 0dp and invisible with null text is redundant but makes it clear that the widget should not appear.)

Here is the XML with these changes:

<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    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/title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="TEST TITLE"
        android:textColor="#FF000000"
        android:textSize="24sp"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent" />

    <TextView
        android:id="@+id/subtitle1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="SUBTITLE 1"
        android:textSize="11sp"
        app:layout_constraintBaseline_toBaselineOf="@+id/viewForBaseline"
        app:layout_constraintHorizontal_chainStyle="packed"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toLeftOf="@+id/subtitleSpace"
        app:layout_constraintRight_toRightOf="parent" />

    <android.support.v4.widget.Space
        android:id="@+id/subtitleSpace"
        android:layout_width="12dp"
        android:layout_height="wrap_content"
        app:layout_constraintLeft_toRightOf="@+id/subtitle1"
        app:layout_constraintRight_toLeftOf="@+id/subtitle2" />

    <TextView
        android:id="@+id/subtitle2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="4dp"
        android:text="SUBTITLE 2"
        android:textSize="14sp"
        android:visibility="gone"
        app:layout_constraintBaseline_toBaselineOf="@+id/viewForBaseline"
        app:layout_constraintLeft_toRightOf="@+id/subtitleSpace"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/title" />

    <TextView
        android:id="@+id/viewForBaseline"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginTop="4dp"
        android:textSize="14sp"
        android:visibility="invisible"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/title" />

</android.support.constraint.ConstraintLayout>