Rotate, Scale and Move in Android (Kotlin)

1_MainActivity.kt

package com.example.myapplication

import android.annotation.SuppressLint
import android.app.Activity
import android.graphics.Matrix
import android.graphics.PointF
import android.os.Bundle
import android.view.ScaleGestureDetector
import androidx.core.view.doOnLayout
import com.almeros.android.multitouch.MoveGestureDetector
import com.almeros.android.multitouch.RotateGestureDetector
import com.example.myapplication.databinding.ActivityMainBinding

@SuppressLint("ClickableViewAccessibility")
class MainActivity : Activity() {
    private lateinit var binding: ActivityMainBinding
    private lateinit var imageMatrix: Matrix
    private var translate = PointF(0f, 0f)
    private var rotate = 0f
    private var scale = 1f

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)

        val imageView = binding.imageView
        imageView.doOnLayout {
            var moveGestureDetector = MoveGestureDetector(this, MoveGestureHandler())
            var rotateGestureDetector = RotateGestureDetector(this, RotateGestureHandler())
            val scaleGestureDetector = ScaleGestureDetector(this, ScaleGestureHandler())
            val center = PointF(
                imageView.measuredWidth.toFloat() / 2f,
                imageView.measuredHeight.toFloat() / 2f
            )

            // Centers the image
            imageMatrix = Matrix().apply {
                setTranslate(
                    center.x - imageView.drawable.intrinsicWidth / 2f,
                    center.y - imageView.drawable.intrinsicHeight / 2f
                )
            }
            imageView.imageMatrix = imageMatrix

            imageView.setOnTouchListener { _, event ->
                moveGestureDetector.onTouchEvent(event)
                rotateGestureDetector.onTouchEvent(event)
                scaleGestureDetector.onTouchEvent(event)

                imageView.imageMatrix = Matrix().apply {
                    set(imageMatrix)
                    postTranslate(-center.x, -center.y)
                    postRotate(rotate)
                    postScale(scale, scale)
                    postTranslate(center.x + translate.x, center.y + translate.y)
                }

                true
            }
        }
    }

    inner class MoveGestureHandler : MoveGestureDetector.SimpleOnMoveGestureListener() {
        override fun onMove(detector: MoveGestureDetector): Boolean {
            translate = detector.focusDelta
            return super.onMove(detector)
        }

        override fun onMoveEnd(detector: MoveGestureDetector) {
            imageMatrix = Matrix(binding.imageView.imageMatrix)
            translate = PointF(0f, 0f)
            super.onMoveEnd(detector)
        }
    }

    inner class RotateGestureHandler : RotateGestureDetector.SimpleOnRotateGestureListener() {
        override fun onRotate(detector: RotateGestureDetector): Boolean {
            rotate = -detector.rotationDegreesDelta
            return super.onRotate(detector)
        }

        override fun onRotateEnd(detector: RotateGestureDetector?) {
            imageMatrix = Matrix(binding.imageView.imageMatrix)
            rotate = 0f
            super.onRotateEnd(detector)
        }
    }

    inner class ScaleGestureHandler : ScaleGestureDetector.SimpleOnScaleGestureListener() {
        override fun onScale(detector: ScaleGestureDetector): Boolean {
            scale = detector.scaleFactor

            return super.onScale(detector)
        }

        override fun onScaleEnd(detector: ScaleGestureDetector?) {
            imageMatrix = Matrix(binding.imageView.imageMatrix)
            scale = 1f
            super.onScaleEnd(detector)
        }
    }
}

2_activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:orientation="vertical"
    tools:context=".MainActivity">

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        android:contentDescription="@string/image_editor"
        android:scaleType="matrix"
        android:src="@mipmap/ic_launcher" />

</LinearLayout>

3_build.gradle

apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'

android {
    compileSdkVersion 29
    buildToolsVersion "29.0.2"

    defaultConfig {
        applicationId "com.example.myapplication"
        minSdkVersion 19
        targetSdkVersion 29
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }

    viewBinding {
        enabled = true
    }

    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }

    kotlinOptions {
        jvmTarget = JavaVersion.VERSION_1_8.toString()
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    implementation 'androidx.appcompat:appcompat:1.1.0'
    implementation 'androidx.core:core-ktx:1.2.0'
    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
    testImplementation 'junit:junit:4.13'
    androidTestImplementation 'androidx.test.ext:junit:1.1.1'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
    implementation 'com.github.Almeros:android-gesture-detectors:v1.0.1'
}