set background when using constraint layout

Question

I am using constraint layout as parent, and added multiple child using constraint. There are three views horizontally and I have to apply rounded corner background for two view only, which was achieved by linear layout previously. But with the help of constraint layout, I am not able to achieve this.

How can I achieve this?

Answer 1

ConstraintLayout recently introduced the concept of constrainthelper which can be used to perform an action on a group of views. 'Group', which is used to toggle visibility of multiple view is subclass of this.

A constrainthelper which changes background of multiple views together is not yet a part of the stable release, but soon will be.

Until then, you can achieve a backround as in the example below, where 3 textview share a common background, using an View class:

<?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"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:background="#AAA">

  <View
    android:id="@+id/background"
    android:layout_width="0dp"
    android:layout_height="0dp"
    android:background="#FFF"
    app:layout_constraintBottom_toBottomOf="@+id/textView3"
    app:layout_constraintEnd_toEndOf="@+id/textView1"
    app:layout_constraintStart_toStartOf="@+id/textView1"
    app:layout_constraintTop_toTopOf="@+id/textView1" />

  <TextView
    android:id="@+id/textView1"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:layout_margin="8dp"
    android:padding="8dp"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    tools:text="TextView" />

  <TextView
    android:id="@+id/textView2"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:padding="8dp"
    app:layout_constraintEnd_toEndOf="@+id/textView1"
    app:layout_constraintStart_toStartOf="@+id/textView1"
    app:layout_constraintTop_toBottomOf="@+id/textView1"
    tools:text="TextView" />

  <TextView
    android:id="@+id/textView3"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:padding="8dp"
    app:layout_constraintEnd_toEndOf="@+id/textView1"
    app:layout_constraintStart_toStartOf="@+id/textView1"
    app:layout_constraintTop_toBottomOf="@+id/textView2"
    tools:text="TextView" />
</android.support.constraint.ConstraintLayout>

EDIT: A nice blog on what to expect from ConstraintLayout 2.0