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)
val seekBarRed = findViewById<SeekBar>(R.id.seekBarRed)
val seekBarGreen = findViewById<SeekBar>(R.id.seekBarGreen)
val seekBarBlue = findViewById<SeekBar>(R.id.seekBarBlue)
val seekBarAlpha = findViewById<SeekBar>(R.id.seekBarAlpha)
val tvIntensity = findViewById<TextView>(R.id.tvIntensity)
// get the bitmap from assets folder
val bitmap = assetsToBitmap("flower103.jpg")
bitmap?.apply {
// show original bitmap in first image view
imageView.setImageBitmap(this)
// show initial bitmap on second image view
imageView2.setImageBitmap(scaleChannels())
seekBarRed.setOnSeekBarChangeListener(object:SeekBar
.OnSeekBarChangeListener{
override fun onProgressChanged(
seekBar: SeekBar?,
progress: Int,
fromUser: Boolean
) {
val red = progress.toFloat()/10
val green = seekBarGreen.progress.toFloat()/10
val blue = seekBarBlue.progress.toFloat()/10
val alpha = seekBarAlpha.progress.toFloat()/10
imageView2.setImageBitmap(
scaleChannels(red,green,blue,alpha))
tvIntensity.text = "(Red $red : Green $green : "
tvIntensity.append("Blue $blue : Alpha $alpha)")
}
override fun onStartTrackingTouch(seekBar: SeekBar?) {
}
override fun onStopTrackingTouch(seekBar: SeekBar?) {
}
})
seekBarGreen.setOnSeekBarChangeListener(object:SeekBar
.OnSeekBarChangeListener{
override fun onProgressChanged(
seekBar: SeekBar?,
progress: Int,
fromUser: Boolean
) {
val red = seekBarRed.progress.toFloat()/10
val green = progress.toFloat()/10
val blue = seekBarBlue.progress.toFloat()/10
val alpha = seekBarAlpha.progress.toFloat()/10
imageView2.setImageBitmap(
scaleChannels(red,green,blue,alpha))
tvIntensity.text = "(Red $red : Green $green : "
tvIntensity.append("Blue $blue : Alpha $alpha)")
}
override fun onStartTrackingTouch(seekBar: SeekBar?) {
}
override fun onStopTrackingTouch(seekBar: SeekBar?) {
}
})
seekBarBlue.setOnSeekBarChangeListener(object:SeekBar
.OnSeekBarChangeListener{
override fun onProgressChanged(
seekBar: SeekBar?,
progress: Int,
fromUser: Boolean
) {
val red = seekBarRed.progress.toFloat()/10
val green = seekBarGreen.progress.toFloat()/10
val blue = progress.toFloat()/10
val alpha = seekBarAlpha.progress.toFloat()/10
imageView2.setImageBitmap(
scaleChannels(red,green,blue,alpha))
tvIntensity.text = "(Red $red : Green $green : "
tvIntensity.append("Blue $blue : Alpha $alpha)")
}
override fun onStartTrackingTouch(seekBar: SeekBar?) {
}
override fun onStopTrackingTouch(seekBar: SeekBar?) {
}
})
seekBarAlpha.setOnSeekBarChangeListener(object:SeekBar
.OnSeekBarChangeListener{
override fun onProgressChanged(
seekBar: SeekBar?,
progress: Int,
fromUser: Boolean
) {
val red = seekBarRed.progress.toFloat()/10
val green = seekBarGreen.progress.toFloat()/10
val blue = seekBarBlue.progress.toFloat()/10
val alpha = progress.toFloat()/10
imageView2.setImageBitmap(
scaleChannels(red,green,blue,alpha))
tvIntensity.text = "(Red $red : Green $green : "
tvIntensity.append("Blue $blue : Alpha $alpha)")
}
override fun onStartTrackingTouch(seekBar: SeekBar?) {
}
override fun onStopTrackingTouch(seekBar: SeekBar?) {
}
})
}
}
}
// 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 scale bitmap color channels
fun Bitmap.scaleChannels(
red:Float = 1F,
green:Float = 1F,
blue:Float = 1F,
alpha:Float = 1F
):Bitmap?{
val bitmap = copy(config,true)
val paint = Paint()
val matrix = ColorMatrix().apply {
setScale(red,green,blue,alpha)
}
val filter = ColorMatrixColorFilter(matrix)
paint.colorFilter = filter
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="210dp"
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="Original 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="210dp"
android:layout_marginTop="16dp"
android:scaleType="centerCrop"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/textView" />
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginTop="12dp"
android:padding="8dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@id/imageView2">
<TextView
android:id="@+id/tvIntensity"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:gravity="center_horizontal"
android:text="Channels Intensity"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<SeekBar
android:id="@+id/seekBarRed"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:max="20"
android:progress="10"
android:progressTint="#ff0000"
android:progressBackgroundTint="#ff0000"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/tvIntensity" />
<SeekBar
android:id="@+id/seekBarGreen"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:max="20"
android:progress="10"
android:progressTint="#00ff00"
android:progressBackgroundTint="#00ff00"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/seekBarRed" />
<SeekBar
android:id="@+id/seekBarBlue"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:max="20"
android:progress="10"
android:progressTint="#0000ff"
android:progressBackgroundTint="#0000ff"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/seekBarGreen" />
<SeekBar
android:id="@+id/seekBarAlpha"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:max="20"
android:progress="10"
android:progressTint="#000000"
android:progressBackgroundTint="#000000"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/seekBarBlue" />
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
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