adding a recording audio visualizer

app/build.gradle

@@ -40,4 +40,5 @@ android {
 dependencies {
     implementation 'com.simplemobiletools:commons:5.24.4'
     implementation 'org.greenrobot:eventbus:3.2.0'
+    implementation 'com.github.Armen101:AudioRecordView:1.0.2'
 }

app/src/main/kotlin/com/simplemobiletools/voicerecorder/activities/MainActivity.kt

@@ -44,10 +44,13 @@ class MainActivity : SimpleActivity() {
 
     override fun onResume() {
         super.onResume()
+        val adjustedPrimaryColor = getAdjustedPrimaryColor()
         toggle_recording_button.apply {
             setImageDrawable(getToggleButtonIcon())
-            background.applyColorFilter(getAdjustedPrimaryColor())
+            background.applyColorFilter(adjustedPrimaryColor)
         }
+
+        visualizer.chunkColor = adjustedPrimaryColor
     }
 
     override fun onDestroy() {
@@ -134,6 +137,15 @@ class MainActivity : SimpleActivity() {
     fun gotStatusEvent(event: Events.RecordingStatus) {
         isRecording = event.isRecording
         toggle_recording_button.setImageDrawable(getToggleButtonIcon())
+        if (isRecording) {
+            visualizer.recreate()
+        }
+    }
+
+    @Subscribe(threadMode = ThreadMode.MAIN)
+    fun gotAmplitudeEvent(event: Events.RecordingAmplitude) {
+        val amplitude = event.amplitude
+        visualizer.update(amplitude)
     }
 
     private fun getToggleButtonIcon(): Drawable {

app/src/main/kotlin/com/simplemobiletools/voicerecorder/models/Events.kt

@@ -3,4 +3,5 @@ package com.simplemobiletools.voicerecorder.models
 class Events {
     class RecordingDuration internal constructor(val duration: Int)
     class RecordingStatus internal constructor(val isRecording: Boolean)
+    class RecordingAmplitude internal constructor(val amplitude: Int)
 }

app/src/main/kotlin/com/simplemobiletools/voicerecorder/services/RecorderService.kt

@@ -28,10 +28,13 @@ import java.io.IOException
 import java.util.*
 
 class RecorderService : Service() {
+    private val AMPLITUDE_UPDATE_MS = 100L
+
     private var currFilePath = ""
     private var duration = 0
     private var isRecording = false
-    private var timer = Timer()
+    private var durationTimer = Timer()
+    private var amplitudeTimer = Timer()
     private var recorder: MediaRecorder? = null
 
     override fun onBind(intent: Intent?): IBinder? = null
@@ -50,8 +53,6 @@ class RecorderService : Service() {
     override fun onDestroy() {
         super.onDestroy()
         stopRecording()
-        recorder?.release()
-        recorder = null
     }
 
     // mp4 output format with aac encoding should produce good enough mp3 files according to https://stackoverflow.com/a/33054794/1967672
@@ -81,8 +82,11 @@ class RecorderService : Service() {
                 broadcastRecorderInfo()
                 startForeground(RECORDER_RUNNING_NOTIF_ID, showNotification())
 
-                timer = Timer()
+                durationTimer = Timer()
-                timer.scheduleAtFixedRate(getTimerTask(), 1000, 1000)
+                durationTimer.scheduleAtFixedRate(getDurationUpdateTask(), 1000, 1000)
+
+                amplitudeTimer = Timer()
+                amplitudeTimer.scheduleAtFixedRate(getAmplitudeUpdateTask(), 0, AMPLITUDE_UPDATE_MS)
             } catch (e: IOException) {
                 showErrorToast(e)
                 stopRecording()
@@ -91,7 +95,8 @@ class RecorderService : Service() {
     }
 
     private fun stopRecording() {
-        timer.cancel()
+        durationTimer.cancel()
+        amplitudeTimer.cancel()
         isRecording = false
 
         recorder?.apply {
@@ -151,13 +156,21 @@ class RecorderService : Service() {
         toast(msg, Toast.LENGTH_LONG)
     }
 
-    private fun getTimerTask() = object : TimerTask() {
+    private fun getDurationUpdateTask() = object : TimerTask() {
         override fun run() {
             duration++
             broadcastDuration()
         }
     }
 
+    private fun getAmplitudeUpdateTask() = object : TimerTask() {
+        override fun run() {
+            if (recorder != null) {
+                EventBus.getDefault().post(Events.RecordingAmplitude(recorder!!.maxAmplitude))
+            }
+        }
+    }
+
     @TargetApi(Build.VERSION_CODES.O)
     private fun showNotification(): Notification {
         val channelId = "simple_recorder"

app/src/main/res/layout/activity_main.xml

@@ -1,10 +1,27 @@
 <?xml version="1.0" encoding="utf-8"?>
 <RelativeLayout 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/recorder_holder"
     android:layout_width="match_parent"
     android:layout_height="match_parent">
 
+    <com.visualizer.amplitude.AudioRecordView
+        android:id="@+id/visualizer"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:layout_above="@+id/recording_duration"
+        android:layout_marginTop="@dimen/activity_margin"
+        android:layout_marginEnd="@dimen/activity_margin"
+        android:layout_marginBottom="@dimen/activity_margin"
+        app:chunkAlignTo="center"
+        app:chunkMaxHeight="200dp"
+        app:chunkMinHeight="2dp"
+        app:chunkRoundedCorners="true"
+        app:chunkSoftTransition="true"
+        app:chunkSpace="1dp"
+        app:chunkWidth="3dp" />
+
     <TextView
         android:id="@+id/recording_duration"
         android:layout_width="wrap_content"