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Center a view horizontally, set layout_constraintLeft_toLeftOf and layout_constraintRight_toRightOf to parent. Center a view vertically, set layout_constraintTop_toTopOf and layout_constraintBottom_toBottomOf to parent. Align to the top left.
Bias, in terms of ConstraintLayout , means "if there is extra room, slide the widget in this direction along the axis". The default bias is 0.5, meaning that the widget is centered in the available space.
You can use layout_constraintCircle for center view inside ConstraintLayout .
It's possible to set the center aligned view as an anchor for other views. In the example below "@+id/stat_2" centered horizontally in parent and it serves as an anchor for other views in this layout.
<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/stat_1"
android:layout_width="80dp"
android:layout_height="wrap_content"
android:layout_marginEnd="8dp"
android:gravity="center"
android:maxLines="1"
android:text="10"
android:textColor="#777"
android:textSize="22sp"
app:layout_constraintTop_toTopOf="@+id/stat_2"
app:layout_constraintEnd_toStartOf="@+id/divider_1" />
<TextView
android:id="@+id/stat_detail_1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Streak"
android:textColor="#777"
android:textSize="12sp"
app:layout_constraintTop_toBottomOf="@+id/stat_1"
app:layout_constraintStart_toStartOf="@+id/stat_1"
app:layout_constraintEnd_toEndOf="@+id/stat_1" />
<View
android:id="@+id/divider_1"
android:layout_width="1dp"
android:layout_height="0dp"
android:layout_marginEnd="16dp"
android:background="#ccc"
app:layout_constraintTop_toTopOf="@+id/stat_2"
app:layout_constraintEnd_toStartOf="@+id/stat_2"
app:layout_constraintBottom_toBottomOf="@+id/stat_detail_2" />
<TextView
android:id="@+id/stat_2"
android:layout_width="80dp"
android:layout_height="wrap_content"
android:gravity="center"
android:maxLines="1"
android:text="243"
android:textColor="#777"
android:textSize="22sp"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintBottom_toBottomOf="parent" />
<TextView
android:id="@+id/stat_detail_2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:maxLines="1"
android:text="Calories Burned"
android:textColor="#777"
android:textSize="12sp"
app:layout_constraintTop_toBottomOf="@+id/stat_2"
app:layout_constraintStart_toStartOf="@+id/stat_2"
app:layout_constraintEnd_toEndOf="@+id/stat_2" />
<View
android:id="@+id/divider_2"
android:layout_width="1dp"
android:layout_height="0dp"
android:layout_marginStart="16dp"
android:background="#ccc"
app:layout_constraintBottom_toBottomOf="@+id/stat_detail_2"
app:layout_constraintStart_toEndOf="@+id/stat_2"
app:layout_constraintTop_toTopOf="@+id/stat_2" />
<TextView
android:id="@+id/stat_3"
android:layout_width="80dp"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:gravity="center"
android:maxLines="1"
android:text="3200"
android:textColor="#777"
android:textSize="22sp"
app:layout_constraintTop_toTopOf="@+id/stat_2"
app:layout_constraintStart_toEndOf="@+id/divider_2" />
<TextView
android:id="@+id/stat_detail_3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:maxLines="1"
android:text="Steps"
android:textColor="#777"
android:textSize="12sp"
app:layout_constraintTop_toBottomOf="@+id/stat_3"
app:layout_constraintStart_toStartOf="@+id/stat_3"
app:layout_constraintEnd_toEndOf="@+id/stat_3" />
</android.support.constraint.ConstraintLayout>
Here's how it works on smallest smartphone (3.7 480x800 Nexus One) vs largest smartphone (5.5 1440x2560 Pixel XL)
If you have a ConstraintLayout with some size, and a child View with some smaller size, you can achieve centering by constraining the child's two edges to the same two edges of the parent. That is, you can write:
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
or
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
Because the view is smaller, these constraints are impossible. But ConstraintLayout will do the best it can, and each constraint will "pull" at the child view equally, thereby centering it.
This concept works with any target view, not just the parent.
Below is XML that achieves your desired UI with no nesting of views and no Guidelines (though guidelines are not inherently evil).
<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="wrap_content"
android:background="#eee">
<TextView
android:id="@+id/title1"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginBottom="12dp"
android:gravity="center"
android:textColor="#777"
android:textSize="22sp"
android:text="10"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toLeftOf="@+id/divider1"
app:layout_constraintBottom_toBottomOf="parent"/>
<TextView
android:id="@+id/label1"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:gravity="center"
android:textColor="#777"
android:textSize="12sp"
android:text="Streak"
app:layout_constraintTop_toBottomOf="@+id/title1"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toLeftOf="@+id/divider1"/>
<View
android:id="@+id/divider1"
android:layout_width="1dp"
android:layout_height="55dp"
android:layout_marginTop="12dp"
android:layout_marginBottom="12dp"
android:background="#ccc"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintLeft_toRightOf="@+id/title1"
app:layout_constraintRight_toLeftOf="@+id/title2"
app:layout_constraintBottom_toBottomOf="parent"/>
<TextView
android:id="@+id/title2"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginBottom="12dp"
android:gravity="center"
android:textColor="#777"
android:textSize="22sp"
android:text="243"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintLeft_toRightOf="@+id/divider1"
app:layout_constraintRight_toLeftOf="@+id/divider2"
app:layout_constraintBottom_toBottomOf="parent"/>
<TextView
android:id="@+id/label2"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:gravity="center"
android:textColor="#777"
android:textSize="12sp"
android:text="Calories Burned"
app:layout_constraintTop_toBottomOf="@+id/title2"
app:layout_constraintLeft_toRightOf="@+id/divider1"
app:layout_constraintRight_toLeftOf="@+id/divider2"/>
<View
android:id="@+id/divider2"
android:layout_width="1dp"
android:layout_height="55dp"
android:layout_marginTop="12dp"
android:layout_marginBottom="12dp"
android:background="#ccc"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintLeft_toRightOf="@+id/title2"
app:layout_constraintRight_toLeftOf="@+id/title3"
app:layout_constraintBottom_toBottomOf="parent"/>
<TextView
android:id="@+id/title3"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginBottom="12dp"
android:gravity="center"
android:textColor="#777"
android:textSize="22sp"
android:text="3200"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintLeft_toRightOf="@+id/divider2"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintBottom_toBottomOf="parent"/>
<TextView
android:id="@+id/label3"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:gravity="center"
android:textColor="#777"
android:textSize="12sp"
android:text="Steps"
app:layout_constraintTop_toBottomOf="@+id/title3"
app:layout_constraintLeft_toRightOf="@+id/divider2"
app:layout_constraintRight_toRightOf="parent"/>
</android.support.constraint.ConstraintLayout>
May be i did not fully understand the problem, but, centering all view inside a ConstraintLayout seems very simple. This is what I used:
<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="wrap_content"
android:layout_gravity="center">
Last two lines did the trick!
<TextView
android:id="@+id/tvName"
style="@style/textViewBoldLarge"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:text="Welcome"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"/>
You can easily center multiple things by creating a chain. It works both vertically and horizontally
Link to official documentation about chains
Edit to answer comment :
<?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/first_score"
android:layout_width="60dp"
android:layout_height="wrap_content"
android:text="10"
app:layout_constraintEnd_toStartOf="@+id/second_score"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="@+id/second_score"
app:layout_constraintBottom_toTopOf="@+id/subtitle"
app:layout_constraintHorizontal_chainStyle="spread"
app:layout_constraintVertical_chainStyle="packed"
android:gravity="center"
/>
<TextView
android:id="@+id/subtitle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Subtitle"
app:layout_constraintTop_toBottomOf="@+id/first_score"
app:layout_constraintBottom_toBottomOf="@+id/second_score"
app:layout_constraintStart_toStartOf="@id/first_score"
app:layout_constraintEnd_toEndOf="@id/first_score"
/>
<TextView
android:id="@+id/second_score"
android:layout_width="60dp"
android:layout_height="120sp"
android:text="243"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toStartOf="@+id/thrid_score"
app:layout_constraintStart_toEndOf="@id/first_score"
app:layout_constraintTop_toTopOf="parent"
android:gravity="center"
/>
<TextView
android:id="@+id/thrid_score"
android:layout_width="60dp"
android:layout_height="wrap_content"
android:text="3200"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="@id/second_score"
app:layout_constraintTop_toTopOf="@id/second_score"
app:layout_constraintBottom_toBottomOf="@id/second_score"
android:gravity="center"
/>
</android.support.constraint.ConstraintLayout>
You have the horizontal chain : first_score <=> second_score <=> third_score.
second_score is centered vertically. The other scores are centered vertically according to it.
You can definitely create a vertical chain first_score <=> subtitle and center it according to second_score
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