How to apply aspect ratio from material design specs on a view?

Question

I am designing an CardView for my app with a rich media header.

I try to make something like this:

According to google material design specification, the picture should have a 16:9 aspect ratio:

So, my question, how to achieve this (Code or XML) ?

If I use a defined size, it will not be a real 16:9 aspect ratio and I will have to handle many resource files for all screen sizes and orientations.

Else, I did not succeed to set a size by code because in onBindViewHolder(...), getWidth() on my view return 0.

Any idea ?

Answer 1

Now with both PercentFrameLayout and PercentRelativeLayout being deprecated in 26.0.0, you should consider using of ConstraintLayout to build out your cards.

Here is the xml snippet for your case:

<android.support.v7.widget.CardView
    xmlns:android="http://schemas.android.com/apk/res/android"
    style="@style/CardView.Light"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginTop="8dp"
    android:layout_marginStart="8dp"
    android:layout_marginEnd="8dp">

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

        <ImageView
            android:id="@+id/media_image"
            android:layout_width="0dp"
            android:layout_height="0dp"
            android:layout_marginTop="0dp"
            android:layout_marginEnd="0dp"
            android:layout_marginStart="0dp"
            android:layout_marginBottom="16dp"
            android:scaleType="centerCrop"
            app:srcCompat="@android:color/darker_gray"
            app:layout_constraintDimensionRatio="H,16:9"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintBottom_toTopOf="@+id/supporting_text"
            app:layout_constraintVertical_chainStyle="spread_inside" />

        <TextView
            android:id="@+id/supporting_text"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_marginTop="16dp"
            android:layout_marginStart="16dp"
            android:layout_marginEnd="16dp"
            android:layout_marginBottom="16dp"
            android:text="Greyhound divisively hello coldly wonderfully marginally far upon excluding."
            android:textAppearance="@style/TextAppearance.AppCompat.Body1"
            android:textColor="#DE000000"
            app:layout_constraintTop_toBottomOf="@+id/media_image"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintBottom_toBottomOf="parent" />

    </android.support.constraint.ConstraintLayout>

</android.support.v7.widget.CardView>

You can check out other card implementations via ConstraintLayout here. All of them were built in compliance with Material design guidelines.

Answer 2

The easiest way would be to use PercentRelativeLayout as the parent ViewGroup. Then you can set the follow XML attributes on your ImageView

 app:layout_widthPercent="100%"
 app:layout_aspectRatio="178%"

Another option is to write your own custom ImageView and override onMeasure() to ensure that the view ends up with a 16:9 ratio. This answer shows you how to do that.