ConstraintLayout: how to have a view be half the screen width and centered?

Solution 1:

With the beta release you can use percentage widths. If you cannot use the beta release, you can employ two vertical guidelines: one at 25% of the screen width and one at 75% of the width. The view with a width of 0dp would be constrained between these two guidelines. This setup will give you a view that is 1/2 of the screen width and also centered.

The following XML demonstrates both ways; one using the ConstraintLayout beta release and the second using features available in the current production release.

XML Layout

<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/activity_main_inference"
    android:layout_width="match_parent"
    android:layout_height="match_parent">


    <View
        android:id="@+id/viewTop"
        android:layout_width="0dp"
        android:layout_height="100dp"
        android:layout_marginTop="16dp"
        android:background="@android:color/darker_gray"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintWidth_default="percent"
        app:layout_constraintWidth_percent="0.5" />


    <android.support.constraint.Guideline
        android:id="@+id/guidelineLeft"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        app:layout_constraintGuide_percent="0.25" />

    <View
        android:layout_width="0dp"
        android:layout_height="100dp"
        android:layout_marginTop="16dp"
        android:background="@android:color/darker_gray"
        app:layout_constraintEnd_toStartOf="@id/guidelineRight"
        app:layout_constraintStart_toEndOf="@id/guidelineLeft"
        app:layout_constraintTop_toBottomOf="@id/viewTop" />

    <android.support.constraint.Guideline
        android:id="@+id/guidelineRight"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        app:layout_constraintGuide_percent="0.75" />

</android.support.constraint.ConstraintLayout>

Solution 2:

As of** ConstraintLayout1.1.0-beta1**, you can use percent to define widths & heights.

android:layout_width="0dp"
app:layout_constraintWidth_default="percent"
app:layout_constraintWidth_percent=".4"

This will define the width to be 40% of the width of the screen. A combination of this and guidelines in percent allow you to create any percent based layout you want.

Solution 3:

try this vertically divide

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

        <android.support.constraint.ConstraintLayout
            android:id="@+id/clPart1"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:background="@color/white"
            android:visibility="visible"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintHorizontal_chainStyle="spread"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toLeftOf="@+id/clPart2">


        </android.support.constraint.ConstraintLayout>

        <android.support.constraint.ConstraintLayout
            android:id="@+id/clPart2"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:background="@color/black"
            android:visibility="visible"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintLeft_toRightOf="@+id/clPart1"
            app:layout_constraintRight_toRightOf="parent">


        </android.support.constraint.ConstraintLayout>
    </android.support.constraint.ConstraintLayout>

Solution 4:

With ConstraintLayout, you can center a view in the screen like this:

<?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">

    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:background="#FF0000"
        android:orientation="vertical"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintHeight_percent=".5"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintWidth_percent=".5"></LinearLayout>

</android.support.constraint.ConstraintLayout>

Update your gradle to the last version of ConstraintLayout:

dependencies {
...
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
}