ConstraintLayout - proportional width / height for yourself?

Question

I am trying to figure out how to achieve the following behavior using the layout constraint:

• Put the view in the center of the ConstraintLayout parent
• Make the view width equal to half the width of the parent
• Make the viewing height equal to its width

(i.e. put the square in the center)

I tried using this combination:

  android:layout_width="0dp"
  android:layout_height="0dp"
  app:layout_constraintBottom_toBottomOf="parent"
  app:layout_constraintEnd_toEndOf="parent"
  app:layout_constraintStart_toStartOf="parent"
  app:layout_constraintTop_toTopOf="parent"
  app:layout_constraintDimensionRatio="2:1"

But I'm not sure how to proceed here

Answer 1

To increase your child’s width to half that of the parent, use the “Recommendations”: the left is 0.25 percent and the right is 0.75.

Then put your presentation between these recommendations.

And finally set layout_constraintDimensionRatio to '1: 1':

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

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

    <View
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:background="@color/colorAccent"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintDimensionRatio="1:1"
        app:layout_constraintLeft_toLeftOf="@id/guideline_left"
        app:layout_constraintRight_toRightOf="@id/guideline_right"
        app:layout_constraintTop_toTopOf="parent"/>
</android.support.constraint.ConstraintLayout>

Answer 2

Guideline, .

: layout_constraintWidth_percent = "0.5"

ConstraintLayout: 1.1.0-beta5 .

<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">

    <ImageView
        android:id="@+id/img_icon"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:background="@color/dark_red"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintDimensionRatio="1:1"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintWidth_percent="0.5" />

</android.support.constraint.ConstraintLayout>

Answer 3

, ( ). ( - 25% - 75%), . /. / 1:1, .

<?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.support.constraint.Guideline
        android:id="@+id/guideline1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        app:layout_constraintGuide_percent="0.25" />

    <android.support.constraint.Guideline
        android:id="@+id/guideline2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        app:layout_constraintGuide_percent="0.75" />

    <View
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintDimensionRatio="1:1"
        app:layout_constraintEnd_toEndOf="@id/guideline2"
        app:layout_constraintStart_toStartOf="@id/guideline1"
        app:layout_constraintTop_toTopOf="parent" />

</android.support.constraint.ConstraintLayout>

Answer 4

I don’t understand why you have to use complex Guideline systems when you can also just use:

app:layout_constraintWidth_percent="0.5"

for half the width of the parent and

app:layout_constraintDimensionRatio="1:1"

to reach the same height as the width.

Fyi: This aspect ratio takes all numbers and even doubles.

Here is the full code with the center:

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
    style="@style/parentViewStyle"
    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">

    <View
        android:id="@+id/view"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintWidth_percent="0.5"
        app:layout_constraintDimensionRatio="1:1"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintHorizontal_bias="0.5" />

</android.support.constraint.ConstraintLayout>