android kotlin - Get screen width and height in dp

MainActivity.kt


package com.example.jetpack

import android.app.Activity
import android.graphics.Point
import android.os.Build
import android.os.Bundle
import android.util.DisplayMetrics
import androidx.appcompat.app.AppCompatActivity
import kotlinx.android.synthetic.main.activity_main.*
import kotlin.math.roundToInt


class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        // show screen size in dp
        textView.text = "Screen size in dp"

        screenSizeInDp.apply {
            // screen width in dp
            textView.append("\n\nWidth : $x dp")

            // screen height in dp
            textView.append("\nHeight : $y dp")
        }
    }
}


// extension property to get display metrics instance
val Activity.displayMetrics: DisplayMetrics
    get() {
        // display metrics is a structure describing general information
        // about a display, such as its size, density, and font scaling
        val displayMetrics = DisplayMetrics()

        if (Build.VERSION.SDK_INT >= 30){
            display?.apply {
                getRealMetrics(displayMetrics)
            }
        }else{
            // getMetrics() method was deprecated in api level 30
            windowManager.defaultDisplay.getMetrics(displayMetrics)
        }

        return displayMetrics
    }


// extension property to get screen width and height in dp
val Activity.screenSizeInDp: Point
    get() {
        val point = Point()
        displayMetrics.apply {
            // screen width in dp
            point.x = (widthPixels / density).roundToInt()

            // screen height in dp
            point.y = (heightPixels / density).roundToInt()
        }

        return point
    }

activity_main.xml


<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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:id="@+id/constraintLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    android:background="#E5E4E2">

    <TextView
        android:id="@+id/textView"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginTop="32dp"
        android:layout_marginEnd="16dp"
        tools:text="TextView"
        android:fontFamily="sans-serif-condensed"
        android:textSize="30sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>