android kotlin - Circular ImageView programmatically

MainActivity.kt


package com.example.jetpack

import android.content.Context
import android.graphics.*
import android.os.Bundle
import android.util.TypedValue
import androidx.appcompat.app.AppCompatActivity
import androidx.core.graphics.drawable.RoundedBitmapDrawable
import androidx.core.graphics.drawable.RoundedBitmapDrawableFactory
import kotlinx.android.synthetic.main.activity_main.*
import java.io.IOException
import kotlin.math.min


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

        // get bitmap from assets folder
        val bitmap: Bitmap? = assetsToBitmap("flower7.jpg")

        // make the bitmap circular shape with maximum available size
        bitmap?.circularIt(applicationContext)?.apply {
            imageView.setImageDrawable(this)
        }

        // make the bitmap circular with specified diameter
        bitmap?.circularIt(
            context = applicationContext,
            // make it smaller
            200.dpToPixels(applicationContext)
        )?.apply {
            imageView2.setImageDrawable(this)
        }
    }
}


// extension function to make a bitmap circular
fun Bitmap.circularIt(
    context: Context,
    diameter:Int = min(width,height)
): RoundedBitmapDrawable? {
    // Calculate the bitmap diameter and radius
    val length = min(diameter,min(width,height))
    val radius = length / 2F

    val bitmap = Bitmap.createBitmap(length,length,Bitmap.Config.ARGB_8888)
    val canvas = Canvas(bitmap)
    canvas.drawColor(Color.WHITE)

    // draw bitmap at canvas center
    canvas.drawBitmap(
        this, // bitmap
        (diameter - this.width)/2F, // left
        (diameter - this.height)/2F, // top
        null // paint
    )

    // return the rounded bitmap drawable as circle shape
    return RoundedBitmapDrawableFactory.create(context.resources,bitmap).apply {
        isCircular = true
        setAntiAlias(true)
    }
}


// extension function to convert dp to equivalent pixels
fun Int.dpToPixels(context: Context):Int = TypedValue.applyDimension(
    TypedValue.COMPLEX_UNIT_DIP, this.toFloat(), context.resources.displayMetrics
).toInt()


// extension function to get bitmap from assets
fun Context.assetsToBitmap(fileName: String): Bitmap?{
    return try {
        with(assets.open(fileName)){
            BitmapFactory.decodeStream(this)
        }
    } catch (e: IOException) { null }
}

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"
    android:background="#DCDCDC"
    tools:context=".MainActivity">

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="0dp"
        android:layout_height="280dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        tools:srcCompat="@tools:sample/avatars" />

    <ImageView
        android:id="@+id/imageView2"
        android:layout_width="0dp"
        android:layout_height="280dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="8dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/imageView"
        tools:srcCompat="@tools:sample/avatars" />

</androidx.constraintlayout.widget.ConstraintLayout>