android kotlin - ImageView circle crop

MainActivity.kt


package com.example.jetpack

import android.content.Context
import android.graphics.*
import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity
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("flower9.jpg")

        // show bitmap on first image view
        bitmap?.apply { imageView.setImageBitmap(this) }

        // crop specified size circular area from bitmap
        bitmap?.cropCircularArea(700)?.apply {
            imageView2.setImageBitmap(this)
            textView.text = "Circular image view, crop radius: 350 pixels"
        }
    }
}


// extension function to crop specified size circular area from bitmap
fun Bitmap.cropCircularArea(
    diameter:Int = min(width,height)
):Bitmap?{
    val bitmap = Bitmap.createBitmap(
        width, // width in pixels
        height, // height in pixels
        Bitmap.Config.ARGB_8888
    )

    val canvas = Canvas(bitmap)

    // create a circular path
    val path = Path()
    val length = min(diameter,min(width,height))
    val radius = length / 2F // in pixels
    path.apply {
        addCircle(
            width/2f,
            height/2f,
            radius,
            Path.Direction.CCW
        )
    }

    // draw circular bitmap on canvas
    canvas.clipPath(path)
    canvas.drawBitmap(this,0f,0f,null)

    val x = (width - length)/2
    val y = (height - length)/2

    // return cropped circular bitmap
    return Bitmap.createBitmap(
        bitmap, // source bitmap
        x, // x coordinate of the first pixel in source
        y, // y coordinate of the first pixel in source
        length, // width
        length // height
    )
}


// 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="260dp"
        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="260dp"
        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" />

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="8dp"
        tools:text="TextView"
        android:fontFamily="sans-serif-condensed-medium"
        style="@style/TextAppearance.AppCompat.Medium"
        app:layout_constraintEnd_toEndOf="@+id/imageView2"
        app:layout_constraintStart_toStartOf="@+id/imageView2"
        app:layout_constraintTop_toBottomOf="@+id/imageView2" />

</androidx.constraintlayout.widget.ConstraintLayout>