ConstraintLayout layout_constraintDimensionRatio not working

Question

I used constraintLayout and layout_constraintDimensionRatio="1:1" (width is wrap_content, height is 0dp (match_constraint))

As a result, I expected width and height to be 1:1, but it's not working.

What is wrong?

I attached code and screenshot.

<?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">

    <TextView
        android:id="@+id/t1"
        android:layout_width="wrap_content"
        android:layout_height="0dp"
        android:background="@android:color/holo_blue_bright"
        android:gravity="center"
        android:text="Hello World!11"
        app:layout_constraintDimensionRatio="1:1" />

</android.support.constraint.ConstraintLayout>

screenshot

I quote android developer site about Constraintlayout. https://developer.android.com/reference/android/support/constraint/ConstraintLayout.html#DimensionConstraints

Ratio :: You can also define one dimension of a widget as a ratio of the other one. In order to do that, you need to have at least one constrained dimension be set to 0dp (i.e., MATCH_CONSTRAINT), and set the attribute layout_constraintDimentionRatio to a given ratio. For example:

     <Button android:layout_width="wrap_content"
               android:layout_height="0dp"
               app:layout_constraintDimensionRatio="1:1" />
     
  will set the height of the button to be the same as its width.

but it was not working.

Answer 1

You forget to add your constraints

<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">      <TextView         android:id="@+id/t1"         android:layout_width="0dp"         android:layout_height="0dp"         app:layout_constraintLeft_toLeftOf="parent"         app:layout_constraintRight_toRightOf="parent"         app:layout_constraintTop_toTopOf="parent"         app:layout_constraintBottom_toBottomOf="parent"         android:background="@android:color/holo_blue_bright"         android:gravity="center"         android:text="Hello World!11"         app:layout_constraintDimensionRatio="1" />  </android.support.constraint.ConstraintLayout> 

0dp is only applied to the child views of ConstraintLayout. Any view should apply the attribute rules of its parent.

Answer 2

As off version 1.1.0 this has changed.

You can now define:

app:layout_constraintDimensionRatio="1:1" app:layout_constraintDimensionRatio="W,1:1" app:layout_constraintDimensionRatio="H,1:1" 

Check the link below to find all the documentation regarding DimensionConstraints:

Link to the docs

Answer 3

In my case I have a problem like i have to fill my layout inside container with A4 size paper ratio.

Problem

I am getting A4 size resume pages as images from backend so i have to append those images in Viewpager in which i am using ImageView to display those images.

Solution

I went through Constraint layout document in which Ratio section is there. So i can use layout_constraintDimensionRatio for solving my problem.

So my xml that is used to Display the whole Layout is following, in my case i have used app:layout_constraintDimensionRatio="1:1.27" as with:height ratio but the actual ratio is app:layout_constraintDimensionRatio="1:1.41"

<?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"
    android:background="@color/orange">

    <!-- divider line which i used as restricting my A4 size container height-->

    <View
        android:id="@+id/divider"
        android:layout_width="match_parent"
        android:layout_height="1dp"
        android:background="@color/headline_title_color"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias=".85"/>

    <!-- A4 size Image View-->

    <ImageView
        android:id="@+id/resumeContainer"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginLeft="12dp"
        android:layout_marginTop="16dp"
        android:layout_marginRight="12dp"
        android:layout_marginBottom="16dp"
        android:background="@color/green"
        android:text="@string/change"
        android:src="@drawable/banner"
        app:layout_constraintBottom_toTopOf="@id/divider"
        app:layout_constraintDimensionRatio="1:1.27"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        />

    <!-- for Bottom two buttons -->

    <com.bold.job.utils.CustomButton
        android:id="@+id/preview"
        style="@style/tertiaryButtonStyle"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_margin="16dp"
        android:onClick="preview"
        android:text="@string/preview_resume"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toLeftOf="@id/guideline"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintTop_toBottomOf="@id/divider"
        />

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

    <com.bold.job.utils.CustomButton
        android:id="@+id/preview2"
        style="@style/tertiaryButtonStyle"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_margin="16dp"
        android:onClick="preview"
        app:layout_constraintLeft_toRightOf="@id/guideline"
        app:layout_constraintRight_toRightOf="parent"
        android:text="@string/preview_resume"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintTop_toBottomOf="@id/divider"
        />


</android.support.constraint.ConstraintLayout>