SizeUtils.kt

import android.content.Context
import android.graphics.Point
import android.os.Build
import android.view.WindowManager
import kotlin.math.pow
import kotlin.math.sqrt

/**
 * An extension function to return current device real width and height
 */
fun WindowManager.currentDeviceRealSize(): Pair<Int, Int> {
    return if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
        return Pair(
            maximumWindowMetrics.bounds.width(),
            maximumWindowMetrics.bounds.height())
    } else {
        val size = Point()
        defaultDisplay.getRealSize(size)
        Pair(size.x, size.y)
    }
}

/**
 * Utility class, where I've collected all the functions from my medium
 * article - https://medium.com/@hayk.mkrtchyan8998/cracking-android-screen-sizes-88228822-98b28d23260c
 *
 * @param context - to get DisplayMetrics instance
 * @param windowManager - to use the above extension function.
 *
 * You can retrieve windowManager instance from the activity.
 */
class SizeUtils(
    private val context: Context,
    private val windowManager: WindowManager
) {

    /**
     * Doesn't return correct values most of the time
     */
    private val displayMetrics = context.resources.displayMetrics
    private val density = displayMetrics.density //The scale factor of the density
    private val densityDpi = displayMetrics.densityDpi // The density of the screen


    /**
     * Works more accurate
     */
    private val xdpi = displayMetrics.xdpi // The pixels count in inch for screen width
    private val ydpi = displayMetrics.ydpi // The pixels count in inch for screen height


    /**
     * The below function returns current device
     * screen width and height in inches
     */
    fun getScreenWidthAndHeightInInches(): Pair<Float, Float> {
        val (width, height) = windowManager.currentDeviceRealSize()
        val displayMetrics = context.resources.displayMetrics
        val widthInInches = width / displayMetrics.xdpi
        val heightInInches = height / displayMetrics.ydpi
        return Pair(widthInInches, heightInInches)
    }


    /**
     * Calculate screen size using Pythagorean theorem
     */
    fun getDeviceScreenSize(): Double {
        val (width, height) = windowManager.currentDeviceRealSize()
        val widthInInches: Double = (width / xdpi).toDouble()
        val heightInInches: Double = (height / ydpi).toDouble()

        val widthAndHeightSum = widthInInches.pow(2) + heightInInches.pow(2)
        val screenSize = sqrt(widthAndHeightSum)

        /* Or instead of above 2 lines of code we can write
           val screenSize = hypot(widthInInches, heightInInches)
        */

        return screenSize
    }
}