ImageSwitcher in Kotlin

Android ImageSwitcher is a user interface widget that provides a smooth transition animation effect to the images while switching between them to display in the view. ImageSwitcher is subclass of View Switcher which is used to animates one image and displays next one. Generally, we use ImageSwitcher in two ways manually in XML layout and programmatically in Kotlin file.

We should define an XML component, to use ImageSwitcher in our android application. 

<ImageSwitcher 
    android:id="@+id/view"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
</ImageSwitcher>

Different attributes of ImageSwitcher widget

Steps of Implementing ImageSwitcher

Step 1: Create a new project in Android Studio

First we create a new project by following the below steps: 

1. Click on File, then New => New Project.
2. After that include the Kotlin support and click on next.
3. Select the minimum SDK as per convenience and click next button.
4. Then select the Empty activity => next => finish.

Step 2: Modify activity_main.xml file

In this file, we use constraint layout with ImageSwitcher and Buttons.

activity_main.xml:

<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/main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/white"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <ImageSwitcher
        android:id="@+id/imageSwitcher"
        android:layout_width="match_parent"
        android:layout_height="250dp"
        android:layout_margin="8dp"
        app:layout_constraintBottom_toTopOf="@+id/prev"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/prev"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:backgroundTint="@color/main_green_stroke_color"
        android:text="Prev"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toStartOf="@+id/next"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.5" />

    <Button
        android:id="@+id/next"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:backgroundTint="@color/main_green_stroke_color"
        android:text="Next"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@+id/prev"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.5" />

</androidx.constraintlayout.widget.ConstraintLayout>

Design UI:

Step 3: Access ImageSwitcher in MainActivity.kt file

Different methods of ImageSwitcher widget:

1. setImageDrawable: It is used to set a new drawable on the next ImageView in the switcher.
2. setImageResource: It is used to set a new image on the ImageSwitcher with the given resource id.
3. setImageURI: It is used to set a new image on the ImageSwitcher with the given URI.

First, we declare an array which contains the resource of the images used for the ImageView. 

private val array = intArrayOf(R.drawable.grape, R.drawable.guava, R.drawable.orange)

then, we access the ImageSwitcher from the XML layout and set ImageView to display the image. 

val imgSwitcher: ImageSwitcher = findViewById(R.id.imageSwitcher)
imgSwitcher.setFactory({
    val imgView = ImageView(applicationContext)
    imgView.scaleType = ImageView.ScaleType.FIT_CENTER
    imgView.setPadding(8, 8, 8, 8)
    imgView
})

Also, we will use one of the above method for ImageSwitcher. 

imgSwitcher.setImageResource(array[index])

MainActivity.kt:

package org.geeksforgeeks.demo

import androidx.appcompat.app.AppCompatActivity

import android.os.Bundle
import android.view.animation.AnimationUtils
import android.widget.Button
import android.widget.ImageSwitcher
import android.widget.ImageView

class MainActivity : AppCompatActivity() {

    private val array = intArrayOf(R.drawable.grape,
        R.drawable.guava, R.drawable.orange)
    private var index = 0

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

        // access the ImageSwitcher
        val imgSwitcher: ImageSwitcher = findViewById(R.id.imageSwitcher)

        imgSwitcher.setFactory({
            val imgView = ImageView(applicationContext)
            imgView.scaleType = ImageView.ScaleType.FIT_CENTER
            imgView.setPadding(8, 8, 8, 8)
            imgView
        })

        // set the method and pass array as a parameter
        imgSwitcher.setImageResource(array[index])

        val imgIn = AnimationUtils.loadAnimation(
            this, android.R.anim.slide_in_left)
        imgSwitcher.inAnimation = imgIn

        val imgOut = AnimationUtils.loadAnimation(
            this, android.R.anim.slide_out_right)
        imgSwitcher.outAnimation = imgOut

        // previous button functionality
        val prev = findViewById<Button>(R.id.prev)
        prev.setOnClickListener {
            index = if (index - 1 >= 0) index - 1 else 2
            imgSwitcher.setImageResource(array[index])
        }
        // next button functionality
        val next = findViewById<Button>(R.id.next)
        next.setOnClickListener {
            index = if (index + 1 < array.size) index +1 else 0
            imgSwitcher.setImageResource(array[index])
        }
    }
}

Output:

Click next button then we get the other animated image in the View.