I wanted a picture background. When I set the background property of the root element to the picture, it was distorted due to aspect ratio difference. After reading StackOverflow answers, I changed it to,
<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">
    <ImageView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:scaleType="centerCrop"
        android:src="@drawable/wallpaper1"/>
The image is a 300KB full HD image. It looks good, but the problem is that when I start the activity, there is a stutter and a warning message.
I/Choreographer: Skipped 38 frames!  The application may be doing too much work on its main thread.
When I removed the ImageView, there was no such problem. Should I not use 'src' in the layout XML, and load the image on my own using a background thread?