android kotlin - Bitmap tint solid color

MainActivity.kt


package com.cfsuman.kotlintutorials

import android.app.Activity
import android.content.Context
import android.graphics.*
import android.os.Bundle
import android.widget.*
import java.io.IOException


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

        // get the widgets reference from XML layout
        val imageView = findViewById<ImageView>(R.id.imageView)
        val imageView2 = findViewById<ImageView>(R.id.imageView2)


        // get the bitmaps from assets folder
        val bitmap = assetsToBitmap("transparent_rose.png")


        bitmap?.apply {
            // show original bitmap in first image view
            imageView.setImageBitmap(this)

            // tint bitmap to solid color
            imageView2.setImageBitmap(
                tintSolidColor(
                    Color.parseColor("#333399")
                )
            )
        }
    }
}



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



// extension function to tint bitmap to solid color
fun Bitmap.tintSolidColor(color:Int = Color.GRAY):Bitmap?{
    val bitmap = copy(config,true)
    val paint = Paint().apply {
        colorFilter = PorterDuffColorFilter(color,PorterDuff.Mode.SRC_IN)
    }
    Canvas(bitmap).drawBitmap(this,0f,0f,paint)
    return bitmap
}

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:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/rootLayout"
    android:background="#DCDCDC"
    android:padding="24dp">

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="0dp"
        android:layout_height="250dp"
        android:scaleType="centerCrop"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="8dp"
        android:text="Source Bitmap"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/imageView" />

    <ImageView
        android:id="@+id/imageView2"
        android:layout_width="0dp"
        android:layout_height="250dp"
        android:layout_marginTop="16dp"
        android:scaleType="centerCrop"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView" />

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="8dp"
        android:text="Bitmap Tint Solid Color"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/imageView2" />

</androidx.constraintlayout.widget.ConstraintLayout>