CODEWITHSUNDEEP
androidandroid-layoutandroid-constraintlayout
Jim
Jim

Reputation: 4415

Buttons do not evenly occupy parent width using constraint layout chains

I am trying to create a chain with 2 buttons at the bottom of a ConstraintLayout using a chain but it is not working. I have removed a couple of views above the buttons for clarity

<?xml version="1.0" encoding="utf-8"?>
<ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    >

<Button
    android:id="@+id/button1"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
     android:layout_alignParentBottom="true"
    android:layout_marginEnd="10dp"
    android:text="Button 1"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toStartOf="@id/button2"
    app:layout_constraintHorizontal_weight="1"
    app:layout_constraintHorizontal_chainStyle="spread"
    app:layout_constraintTop_toBottomOf="@id/guideline" />

<Button
    android:id="@+id/button2"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_marginStart="4dp"
    android:layout_marginEnd="10dp"
    android:text="Button 2"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintHorizontal_weight="1"
    app:layout_constraintStart_toEndOf="@id/button1"
    app:layout_constraintTop_toBottomOf="@id/guideline" />

</ConstraintLayout>

The buttons do show up at the bottom of the screen, one next to each other but they don't occupy the parent width i.e. each being 50% of the screen. They are wrapping around the text at the side of the screen.

What am I doing wrong?

Update:
I see that if I add something other than 0dp e.g. 200dp it expands the views. But I was under the impression that I should be using 0dp to respect the constraints

Upvotes: 0

Views: 323

Answers (1)

hardartcore
hardartcore

Reputation: 17037

Here is an example of implementation spreading two button at the bottom of their parents using ConstraintLayout:

<?xml version="1.0" encoding="utf-8"?>
<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="match_parent">

    <Button
        android:id="@+id/button1"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginEnd="8dp"
        android:layout_marginBottom="16dp"
        android:text="Button 1"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toStartOf="@id/button2"
        app:layout_constraintHorizontal_chainStyle="spread"
        app:layout_constraintStart_toStartOf="parent" />

    <Button
        android:id="@+id/button2"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginEnd="16dp"
        android:layout_marginBottom="16dp"
        android:text="Button 2"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@id/button1" />

</androidx.constraintlayout.widget.ConstraintLayout>

What's the difference between this and your version. For button1 there is additional rule which indicated where is the start of the button: app:layout_constraintStart_toStartOf="parent" and accordingly for button2 where is the end: app:layout_constraintEnd_toEndOf="parent". Which actually helps the ContraintLayout properly layout the buttons.

Btw, you don't need to add android:layout_alignParentBottom="true" to your buttons since the parent is not a RelativeLayout.

Upvotes: 2

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