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android – Group views in ConstraintLayout to treat them as a single view

Posted by: admin April 23, 2020 Leave a comment

Questions:

I need to apply some constraints to a group of views in ConstraintLayout. I want to group these views and continue editing while the layout designer in Android studio treats them as a single view. Is there a way to do so without actually wrapping the views with a ViewGroup (another layout)? If such a wrapper is necessary, maybe there is a wrapper layout that comes with ConstraintLayout and allows to group objects without creating heavy layouts like RelativeLayout?

How to&Answers:

ConstraintLayout Chains

Android developers recently released a new version of ConstraintLayout (1.0.2 as of today). This version contains a new major feature – Chains, which allows us to group views in ConstraintLayout.

Chains provide group-like behavior in a single axis (horizontally or vertically).

A set of widgets are considered a chain if they a linked together via a bi-directional connection

Once a chain is created, there are two possibilities:

  • Spread the elements in the available space
  • A chain can also be “packed”, in that case the elements are grouped together

Currently, you need to use the following gradle dependency to use this feature (since it is an alpha):

 compile 'com.android.support.constraint:constraint-layout:1.0.0-alpha9'

Here you may find the newest version of ConstraintLayout to use in your projects.

Until Android Studio 2.3, Android Studio user interface designer did not support creating chains since you couldn’t add bi-directional constraints in it. The solution was to create these constraints in manually XML, as mentioned by TranslucentCloud. From Android Studio 2.3 (currently only on canary channel), chains are supported in a UI editor as well (as GoRoS mentioned in comments).


Example

Following is an example of how to position two views together in the middle of a screen using ConstraintLayout and chains:

<?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="match_parent">


    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="16dp"
        android:layout_marginStart="16dp"
        android:layout_marginTop="16dp"
        android:text="TextView"
        app:layout_constraintBottom_toTopOf="@+id/button"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.5"
        app:layout_constraintVertical_chainPacked="true"/>

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="16dp"
        android:layout_marginEnd="16dp"
        android:layout_marginStart="16dp"
        android:layout_marginTop="8dp"
        android:text="Button"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView"/>
</android.support.constraint.ConstraintLayout>

Update (Jan, 2018) by @Mateus Gondim

In the recent versions, you should use app:layout_constraintVertical_chainStyle="packed" instead of app:layout_constraintVertical_chainPacked="true"


Answer:

You can use

android.support.constraint.Guideline

to group elements together.

Add a Guideline (vertical or horizontal) and then use that as an anchor for the other views. Here is a simple example of horizontally centering two grouped textviews: (showing design view in AS)

enter image description here

<?xml version="1.0" encoding="utf-8"?>
<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="56dp"
    android:background="@android:color/white"
    android:paddingLeft="16dp"
    android:paddingRight="16dp">


    <TextView
        android:id="@+id/top_text"
        android:layout_width="wrap_content"
        android:layout_height="0dp"
        android:background="@android:color/holo_red_light"
        android:textSize="16sp"
        app:layout_constraintBottom_toTopOf="@+id/guideline"
        android:text="Above"
        tools:text="Above" />

    <android.support.constraint.Guideline
        android:id="@+id/guideline"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        app:layout_constraintGuide_percent="0.5" />

    <TextView
        android:id="@+id/bottom_text"
        android:layout_width="wrap_content"
        android:layout_height="0dp"
        android:background="@android:color/holo_blue_bright"
        android:textSize="16sp"
        app:layout_constraintTop_toBottomOf="@+id/guideline"
        android:text="Below"
        tools:text="Below" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_vertical"
        android:text="Right vertically centered"
        android:textSize="24sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        tools:text="Right vertically centered"/>
</ConstraintLayout>

Answer:

I just want to add some graphics to the great accepted answer. It is very straightforward:

In layout design view > select all the views that you want to group > right-click them > Chains > Create Horizontal Chain:
enter image description here

It is also straightforward to center them:

Select the head view of the group > Organize > Pack Horizontally > set the start constraint of the first view and the end constraint of the last view to their parent:
enter image description here

Answer:

You can use height 0dp and organize views vertically.

in relative layout we can use layout below and above like

<FrameLayout
        android:id="@+id/frame_layout"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_above="@+id/bottom_nav"
        android:layout_below="@+id/toolbar"
        />

In constraint layout giving height is compulsory so you can give 0 height.
and then you can set your view below other views like this

<android.support.v4.view.ViewPager
    android:layout_width="match_parent"
    android:layout_height="0dp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/tablayout" />

you can use constraintTop_toBottomOf and constraintBottom_toTopOf properties to adjust your view to above or below of other.
thanks