Introduce ViewModel and UseCase

app/build.gradle.kts

@@ -1,7 +1,11 @@
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+
 plugins {
     alias(libs.plugins.android.application)
     alias(libs.plugins.kotlin.android)
     alias(libs.plugins.kotlin.compose)
+    alias(libs.plugins.google.ksp)
+    alias(libs.plugins.hilt.android)
 }
 
 android {
@@ -28,11 +32,13 @@ android {
         }
     }
     compileOptions {
-        sourceCompatibility = JavaVersion.VERSION_11
+        sourceCompatibility = JavaVersion.VERSION_21
-        targetCompatibility = JavaVersion.VERSION_11
+        targetCompatibility = JavaVersion.VERSION_21
+    }
+    kotlin {
+        compilerOptions {
+            jvmTarget = JvmTarget.JVM_21
         }
-    kotlinOptions {
-        jvmTarget = "11"
     }
     buildFeatures {
         compose = true
@@ -51,6 +57,9 @@ dependencies {
     implementation(libs.androidx.compose.material3)
     implementation(libs.timber)
     implementation(libs.kotlinx.coroutines.android)
+    implementation(libs.hilt.android)
+    implementation(libs.androidx.hilt.navigation.compose)
+    ksp(libs.hilt.android.compiler)
     testImplementation(libs.junit)
     androidTestImplementation(libs.androidx.junit)
     androidTestImplementation(libs.androidx.espresso.core)

app/src/main/AndroidManifest.xml

@@ -1,11 +1,11 @@
 <?xml version="1.0" encoding="utf-8"?>
-<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
-    xmlns:tools="http://schemas.android.com/tools">
 
     <uses-permission android:name="android.permission.RECORD_AUDIO" />
     <uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS" />
 
     <application
+        android:name=".MyApplication"
         android:allowBackup="true"
         android:dataExtractionRules="@xml/data_extraction_rules"
         android:fullBackupContent="@xml/backup_rules"

app/src/main/java/dev/adriankuta/visualizer/AudioSessionsTracker.kt

@@ -1,17 +0,0 @@
-package dev.adriankuta.visualizer
-
-/**
- * Placeholder for potential future audio session tracking.
- * Currently not used to avoid API-level constraints on older devices.
- */
-class AudioSessionsTracker {
-    /**
-     * Starts tracking audio sessions. No-op in the current placeholder implementation.
-     */
-    fun start() {}
-
-    /**
-     * Stops tracking audio sessions. No-op in the current placeholder implementation.
-     */
-    fun stop() {}
-}

app/src/main/java/dev/adriankuta/visualizer/AudioVisualizer.kt

@@ -0,0 +1,160 @@
+package dev.adriankuta.visualizer
+
+import android.media.audiofx.Visualizer
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.State
+import androidx.compose.ui.graphics.Color
+import dev.adriankuta.visualizer.domain.SoundToColorMapper
+import dev.adriankuta.visualizer.domain.SoundToColorMapperFactory
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.launch
+import timber.log.Timber
+
+/**
+ * Interface for audio visualization functionality.
+ * Follows Interface Segregation Principle.
+ */
+interface AudioVisualizerService {
+    val currentColor: State<Color>
+    val isActive: State<Boolean>
+    
+    fun start()
+    fun stop()
+    fun release()
+}
+
+/**
+ * Implementation of AudioVisualizerService using Android's Visualizer API.
+ * 
+ * Follows Single Responsibility Principle by focusing on audio visualization.
+ * Uses Dependency Injection for the sound-to-color mapper.
+ */
+class AndroidAudioVisualizer(
+    private val soundToColorMapper: SoundToColorMapper = SoundToColorMapperFactory.createDefault(),
+    private val coroutineScope: CoroutineScope = CoroutineScope(Dispatchers.Main)
+) : AudioVisualizerService {
+    
+    companion object {
+        private const val SAMPLING_RATE = 16000 // Hz
+        private const val CAPTURE_SIZE = 1024 // Window size for audio capture
+    }
+    
+    private var visualizer: Visualizer? = null
+    private var processingJob: Job? = null
+    
+    private val _currentColor = mutableStateOf(Color.Black)
+    override val currentColor: State<Color> = _currentColor
+    
+    private val _isActive = mutableStateOf(false)
+    override val isActive: State<Boolean> = _isActive
+    
+    override fun start() {
+        try {
+            // Initialize visualizer with audio session ID 0 (output mix)
+            visualizer = Visualizer(0).apply {
+                captureSize = CAPTURE_SIZE
+                
+                // Set up waveform data listener
+                setDataCaptureListener(
+                    object : Visualizer.OnDataCaptureListener {
+                        override fun onWaveFormDataCapture(
+                            visualizer: Visualizer?,
+                            waveform: ByteArray?,
+                            samplingRate: Int
+                        ) {
+                            waveform?.let { processWaveform(it) }
+                        }
+                        
+                        override fun onFftDataCapture(
+                            visualizer: Visualizer?,
+                            fft: ByteArray?,
+                            samplingRate: Int
+                        ) {
+                            // Not used in this implementation
+                        }
+                    },
+                    Visualizer.getMaxCaptureRate() / 2, // Capture rate
+                    true, // Waveform
+                    false // FFT
+                )
+                
+                enabled = true
+            }
+            
+            _isActive.value = true
+            Timber.d("AudioVisualizer started successfully")
+            
+        } catch (e: Exception) {
+            Timber.e(e, "Failed to start AudioVisualizer")
+            _isActive.value = false
+        }
+    }
+    
+    override fun stop() {
+        try {
+            visualizer?.enabled = false
+            processingJob?.cancel()
+            _isActive.value = false
+            Timber.d("AudioVisualizer stopped")
+        } catch (e: Exception) {
+            Timber.e(e, "Error stopping AudioVisualizer")
+        }
+    }
+    
+    override fun release() {
+        stop()
+        try {
+            visualizer?.release()
+            visualizer = null
+            soundToColorMapper.reset()
+            Timber.d("AudioVisualizer released")
+        } catch (e: Exception) {
+            Timber.e(e, "Error releasing AudioVisualizer")
+        }
+    }
+    
+    private fun processWaveform(waveform: ByteArray) {
+        processingJob?.cancel()
+        processingJob = coroutineScope.launch(Dispatchers.Default) {
+            try {
+                val color = soundToColorMapper.mapSoundToColor(waveform)
+                
+                // Update UI on main thread
+                launch(Dispatchers.Main) {
+                    _currentColor.value = color
+                }
+            } catch (e: Exception) {
+                Timber.e(e, "Error processing waveform")
+            }
+        }
+    }
+}
+
+/**
+ * Factory for creating AudioVisualizerService instances.
+ * Follows Factory Pattern and makes testing easier.
+ */
+object AudioVisualizerFactory {
+    
+    /**
+     * Creates a default Android audio visualizer.
+     */
+    fun createDefault(coroutineScope: CoroutineScope): AudioVisualizerService {
+        return AndroidAudioVisualizer(
+            soundToColorMapper = SoundToColorMapperFactory.createDefault(),
+            coroutineScope = coroutineScope
+        )
+    }
+    
+    /**
+     * Creates an Android audio visualizer with custom mapper.
+     */
+    fun create(
+        soundToColorMapper: SoundToColorMapper,
+        coroutineScope: CoroutineScope
+    ): AudioVisualizerService {
+        return AndroidAudioVisualizer(soundToColorMapper, coroutineScope)
+    }
+}

app/src/main/java/dev/adriankuta/visualizer/HSL.kt

@@ -0,0 +1,95 @@
+package dev.adriankuta.visualizer
+
+import androidx.compose.ui.graphics.Color
+import kotlin.math.sqrt
+
+/**
+ * Represents a color in HSL (Hue, Saturation, Lightness) color space.
+ * 
+ * @param hue The hue component (0-360 degrees)
+ * @param saturation The saturation component (0-1)
+ * @param lightness The lightness component (0-1)
+ */
+data class HSL(
+    val hue: Float,
+    val saturation: Float,
+    val lightness: Float
+) {
+    /**
+     * Converts HSL color to RGB values.
+     * 
+     * @return Triple containing RGB values (0-255)
+     */
+    fun toRgb(): Triple<Int, Int, Int> {
+        val (r, g, b) = hlsToRgb(hue / 360f, lightness, saturation)
+        return Triple((r * 255).toInt(), (g * 255).toInt(), (b * 255).toInt())
+    }
+    
+    /**
+     * Converts HSL color to Compose Color.
+     * 
+     * @return Compose Color object
+     */
+    fun toComposeColor(): Color {
+        val (r, g, b) = toRgb()
+        return Color(r, g, b)
+    }
+    
+    /**
+     * Creates a new HSL color with modified lightness.
+     * 
+     * @param newLightness The new lightness value (0-1)
+     * @return New HSL color with updated lightness
+     */
+    fun withLightness(newLightness: Float): HSL = copy(lightness = newLightness.coerceIn(0f, 1f))
+    
+    private fun hlsToRgb(h: Float, l: Float, s: Float): Triple<Float, Float, Float> {
+        val r: Float
+        val g: Float
+        val b: Float
+
+        if (s == 0f) {
+            // Achromatic (gray)
+            r = l
+            g = l
+            b = l
+        } else {
+            val q = if (l < 0.5f) l * (1f + s) else l + s - l * s
+            val p = 2f * l - q
+
+            r = hueToRgb(p, q, h + 1f / 3f)
+            g = hueToRgb(p, q, h)
+            b = hueToRgb(p, q, h - 1f / 3f)
+        }
+
+        return Triple(r, g, b)
+    }
+
+    private fun hueToRgb(p: Float, q: Float, t: Float): Float {
+        var tTemp = t
+        if (tTemp < 0f) tTemp += 1f
+        if (tTemp > 1f) tTemp -= 1f
+        return when {
+            tTemp < 1f / 6f -> p + (q - p) * 6f * tTemp
+            tTemp < 1f / 2f -> q
+            tTemp < 2f / 3f -> p + (q - p) * (2f / 3f - tTemp) * 6f
+            else -> p
+        }
+    }
+}
+
+/**
+ * Calculates the Root Mean Square (RMS) value of audio data.
+ * 
+ * @param bytes Audio data as byte array
+ * @return RMS value as Double
+ */
+fun calculateRms(bytes: ByteArray): Double {
+    if (bytes.isEmpty()) return 0.0
+    var sum = 0.0
+    for (b in bytes) {
+        val centered = (b.toInt() and 0xFF) - 128
+        sum += centered * centered
+    }
+    return sqrt(sum / bytes.size)
+}

app/src/main/java/dev/adriankuta/visualizer/MainActivity.kt

@@ -1,54 +1,19 @@
 package dev.adriankuta.visualizer
 
-import android.Manifest
-import android.content.pm.PackageManager
 import android.os.Bundle
 import androidx.activity.ComponentActivity
-import androidx.activity.compose.rememberLauncherForActivityResult
 import androidx.activity.compose.setContent
 import androidx.activity.enableEdgeToEdge
-import androidx.activity.result.contract.ActivityResultContracts
-import androidx.compose.foundation.layout.Arrangement
-import androidx.compose.foundation.layout.Column
-import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.fillMaxSize
-import androidx.compose.foundation.layout.fillMaxWidth
-import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
-import androidx.compose.foundation.rememberScrollState
-import androidx.compose.foundation.verticalScroll
-import androidx.compose.material3.HorizontalDivider
-import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Scaffold
-import androidx.compose.material3.Text
-import androidx.compose.runtime.Composable
-import androidx.compose.runtime.DisposableEffect
-import androidx.compose.runtime.getValue
-import androidx.compose.runtime.mutableStateOf
-import androidx.compose.runtime.remember
-import androidx.compose.runtime.setValue
-import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
-import androidx.compose.ui.platform.LocalContext
+import dagger.hilt.android.AndroidEntryPoint
-import androidx.compose.ui.platform.LocalLifecycleOwner
-import androidx.compose.ui.tooling.preview.Preview
-import androidx.compose.ui.unit.dp
-import androidx.core.content.ContextCompat
-import androidx.lifecycle.Lifecycle
-import androidx.lifecycle.LifecycleEventObserver
-import dev.adriankuta.visualizer.components.ControlButtons
-import dev.adriankuta.visualizer.components.FftBarsView
-import dev.adriankuta.visualizer.components.MetricsSection
-import dev.adriankuta.visualizer.components.PermissionSection
-import dev.adriankuta.visualizer.components.WaveformView
 import dev.adriankuta.visualizer.ui.theme.VisualizerTheme
+import dev.adriankuta.visualizer.view.VisualizerScreen
 import timber.log.Timber
 
-/**
+@AndroidEntryPoint
- * Entry point activity that hosts the Compose UI for the audio visualizer demo.
- *
- * Sets up the app theme, window insets, and renders [VisualizerScreen].
- */
 class MainActivity : ComponentActivity() {
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
@@ -60,128 +25,13 @@ class MainActivity : ComponentActivity() {
         setContent {
             VisualizerTheme {
                 Scaffold(modifier = Modifier.fillMaxSize()) { innerPadding ->
-                    VisualizerScreen(modifier = Modifier.padding(innerPadding))
+                    VisualizerScreen(
-                }
-            }
-        }
-    }
-}
-
-/**
- * Top-level screen that manages permission requests and lifecycle of [VisualizerController],
- * and renders the waveform, FFT bars, and simple metrics with control buttons.
- *
- * @param modifier Modifier applied to the screen container.
- */
-@Composable
-private fun VisualizerScreen(modifier: Modifier = Modifier) {
-    val context = LocalContext.current
-    var permissionGranted by remember {
-        mutableStateOf(
-            ContextCompat.checkSelfPermission(
-                context,
-                Manifest.permission.RECORD_AUDIO
-            ) == PackageManager.PERMISSION_GRANTED
-        )
-    }
-
-    val requestPermissionLauncher = rememberLauncherForActivityResult(
-        contract = ActivityResultContracts.RequestPermission()
-    ) { granted ->
-        permissionGranted = granted
-    }
-
-    var waveform by remember { mutableStateOf<ByteArray?>(null) }
-    var fft by remember { mutableStateOf<ByteArray?>(null) }
-
-    val controller = remember(permissionGranted) {
-        VisualizerController(
-            audioSessionId = 0,
-            onWaveform = { data -> waveform = data.clone() },
-            onFft = { data -> fft = data.clone() }
-        )
-    }
-
-    val lifecycleOwner = LocalLifecycleOwner.current
-
-    DisposableEffect(lifecycleOwner, permissionGranted, controller) {
-        val observer = LifecycleEventObserver { _, event ->
-            if (!permissionGranted) return@LifecycleEventObserver
-            when (event) {
-                Lifecycle.Event.ON_CREATE -> runCatching { controller.start() }
-                Lifecycle.Event.ON_DESTROY -> runCatching { controller.stop() }
-                else -> {}
-            }
-        }
-        lifecycleOwner.lifecycle.addObserver(observer)
-        // If permission has just been granted while we are already STARTED/RESUMED,
-        // ensure the visualizer starts immediately (ON_START won't be called again).
-        if (permissionGranted && lifecycleOwner.lifecycle.currentState.isAtLeast(Lifecycle.State.STARTED)) {
-            runCatching { controller.start() }
-        }
-        onDispose {
-            lifecycleOwner.lifecycle.removeObserver(observer)
-            runCatching { controller.stop() }
-        }
-    }
-
-    Column(
-        modifier = modifier
-            .fillMaxSize()
-            .padding(16.dp),
-        verticalArrangement = Arrangement.Top,
-        horizontalAlignment = Alignment.Start
-    ) {
-        Column(
                         modifier = Modifier
-                .fillMaxWidth()
+                            .fillMaxSize()
-                .weight(1f)
+                            .padding(innerPadding)
-                .verticalScroll(rememberScrollState())
-        ) {
-            Text("Android Visualizer Demo", style = MaterialTheme.typography.headlineSmall)
-            Spacer(Modifier.height(8.dp))
-            if (!permissionGranted) {
-                PermissionSection(
-                    permissionGranted = false,
-                    requestPermissionLauncher = requestPermissionLauncher
-                )
-                return@Column
-            }
-
-            Text("Listening to global output. Play music in another app to see data.")
-            Spacer(Modifier.height(8.dp))
-
-            WaveformView(data = waveform)
-
-            Spacer(Modifier.height(8.dp))
-
-            FftBarsView(data = fft)
-
-            Spacer(Modifier.height(12.dp))
-            HorizontalDivider()
-            Spacer(Modifier.height(12.dp))
-
-            MetricsSection(
-                waveform = waveform,
-                fft = fft
                     )
                 }
-        ControlButtons(
+            }
-            onStart = { runCatching { controller.start() } },
+        }
-            onStop = { runCatching { controller.stop() } },
-            modifier = Modifier.align(Alignment.CenterHorizontally)
-        )
-    }
-}
-
-
-/**
- * Preview of [VisualizerScreen] for Android Studio without runtime data.
- */
-@Preview(showBackground = true)
-@Composable
-fun VisualizerPreview() {
-    VisualizerTheme {
-        VisualizerScreen()
     }
 }

app/src/main/java/dev/adriankuta/visualizer/MovingAverage.kt

@@ -0,0 +1,39 @@
+package dev.adriankuta.visualizer
+
+/**
+ * A utility class for calculating moving averages over a sliding window.
+ * Follows the Single Responsibility Principle by focusing solely on moving average calculations.
+ */
+class MovingAverage(private val windowSize: Int) {
+    private val values = mutableListOf<Double>()
+
+    /**
+     * Processes a new value and returns the current moving average.
+     * 
+     * @param newValue The new value to add to the moving average calculation
+     * @return The current moving average
+     */
+    fun process(newValue: Double): Double {
+        values.add(newValue)
+
+        // Remove oldest value if window size exceeded
+        if (values.size > windowSize) {
+            values.removeAt(0)
+        }
+
+        return values.average()
+    }
+
+    /**
+     * Resets the moving average calculation.
+     */
+    fun reset() {
+        values.clear()
+    }
+
+    /**
+     * Returns the current number of values in the window.
+     */
+    val currentSize: Int
+        get() = values.size
+}

app/src/main/java/dev/adriankuta/visualizer/MyApplication.kt

@@ -0,0 +1,8 @@
+package dev.adriankuta.visualizer
+
+import android.app.Application
+import dagger.hilt.android.HiltAndroidApp
+
+@HiltAndroidApp
+class MyApplication: Application() {
+}

app/src/main/java/dev/adriankuta/visualizer/VisualizerController.kt

@@ -1,123 +0,0 @@
-package dev.adriankuta.visualizer
-
-import android.media.audiofx.Visualizer
-import kotlinx.coroutines.*
-import timber.log.Timber
-
-/**
- * Simple wrapper over Android Visualizer to capture global output mix (audio session 0).
- */
-class VisualizerController(
-    private val audioSessionId: Int = 0,
-    private val onWaveform: (ByteArray) -> Unit,
-    private val onFft: (ByteArray) -> Unit,
-) {
-    private var visualizer: Visualizer? = null
-    private val coroutineScope = CoroutineScope(Dispatchers.IO + SupervisorJob())
-    private var loggingJob: Job? = null
-    private var latestWaveform: ByteArray? = null
-    private var latestFft: ByteArray? = null
-
-    /**
-     * Starts capturing audio data via [Visualizer].
-     *
-     * Safe to call multiple times; subsequent calls are no-ops if already started.
-     * If initialization fails (e.g., missing microphone permission or device restriction),
-     * the controller performs cleanup and rethrows the underlying exception.
-     */
-    @Synchronized
-    fun start() {
-        if (visualizer != null) return
-        try {
-            Timber.d("Starting audio visualizer listening (audioSessionId: $audioSessionId)")
-            val v = Visualizer(audioSessionId)
-            // Use the maximum supported capture size for better resolution
-            val captureSize = Visualizer.getCaptureSizeRange().let { it[1] }
-            v.captureSize = captureSize
-            val rate = Visualizer.getMaxCaptureRate() / 2 // decent rate
-            v.setDataCaptureListener(object : Visualizer.OnDataCaptureListener {
-                override fun onWaveFormDataCapture(
-                    visualizer: Visualizer?,
-                    waveform: ByteArray?,
-                    samplingRate: Int
-                ) {
-                    if (waveform != null) {
-                        latestWaveform = waveform.clone()
-                        onWaveform(waveform)
-                    }
-                }
-
-                override fun onFftDataCapture(
-                    visualizer: Visualizer?,
-                    fft: ByteArray?,
-                    samplingRate: Int
-                ) {
-                    if (fft != null) {
-                        latestFft = fft.clone()
-                        onFft(fft)
-                    }
-                }
-            }, rate, true, true)
-            v.enabled = true
-            visualizer = v
-
-            // Start coroutine-based logging for raw data samples every 1 second
-            startDataLogging()
-
-            Timber.i("Audio visualizer listening started successfully")
-        } catch (e: Throwable) {
-            // If Visualizer cannot be initialized (e.g. permission or device restriction), ensure cleanup
-            Timber.e(e, "Failed to start audio visualizer listening")
-            stop()
-            throw e
-        }
-    }
-
-    /**
-     * Stops capturing audio data and releases the underlying [Visualizer].
-     * Safe to call multiple times.
-     */
-    @Synchronized
-    fun stop() {
-        Timber.d("Stopping audio visualizer listening")
-
-        // Stop the logging coroutine
-        loggingJob?.cancel()
-        loggingJob = null
-
-        visualizer?.enabled = false
-        visualizer?.release()
-        visualizer = null
-
-        // Clear latest data
-        latestWaveform = null
-        latestFft = null
-
-        Timber.i("Audio visualizer listening stopped")
-    }
-
-    /**
-     * Starts a coroutine that logs raw data samples every 1 second.
-     */
-    private fun startDataLogging() {
-        loggingJob?.cancel() // Cancel any existing logging job
-        loggingJob = coroutineScope.launch {
-            while (isActive) {
-                delay(1000) // Wait for 1 second
-
-                val waveform = latestWaveform
-                val fft = latestFft
-
-                if (waveform != null && fft != null) {
-                    // Log sample of raw data (first few bytes to avoid too much log spam)
-                    val waveformSample = waveform.take(8).joinToString(", ") { it.toString() }
-                    val fftSample = fft.take(8).joinToString(", ") { it.toString() }
-
-                    Timber.d("Raw data sample - Waveform {size: ${waveform.size}, sample: [$waveformSample...]}, FFT {size: {${fft.size}}, sample: [$fftSample...]}")
-                } else {
-                    Timber.d("Raw data sample - No data available yet")
-                }
-            }
-        }
-    }
-}

app/src/main/java/dev/adriankuta/visualizer/components/ControlButtons.kt

@@ -1,30 +0,0 @@
-package dev.adriankuta.visualizer.components
-
-import androidx.compose.foundation.layout.Row
-import androidx.compose.foundation.layout.Spacer
-import androidx.compose.foundation.layout.width
-import androidx.compose.material3.Button
-import androidx.compose.material3.Text
-import androidx.compose.runtime.Composable
-import androidx.compose.ui.Modifier
-import androidx.compose.ui.unit.dp
-
-/**
- * Simple control row with Start/Stop buttons for the visualizer.
- *
- * @param onStart Invoked when the Start button is pressed.
- * @param onStop Invoked when the Stop button is pressed.
- * @param modifier Compose modifier for layout.
- */
-@Composable
-fun ControlButtons(
-    onStart: () -> Unit,
-    onStop: () -> Unit,
-    modifier: Modifier = Modifier,
-) {
-    Row(modifier = modifier) {
-        Button(onClick = onStart) { Text("Start") }
-        Spacer(Modifier.width(8.dp))
-        Button(onClick = onStop) { Text("Stop") }
-    }
-}

app/src/main/java/dev/adriankuta/visualizer/components/FftBarsView.kt

@@ -1,66 +0,0 @@
-package dev.adriankuta.visualizer.components
-
-import androidx.compose.foundation.Canvas
-import androidx.compose.foundation.layout.fillMaxWidth
-import androidx.compose.foundation.layout.height
-import androidx.compose.foundation.layout.padding
-import androidx.compose.material3.MaterialTheme
-import androidx.compose.material3.Text
-import androidx.compose.runtime.Composable
-import androidx.compose.ui.Modifier
-import androidx.compose.ui.graphics.Color
-import androidx.compose.ui.unit.dp
-import kotlin.math.hypot
-import kotlin.math.min
-
-/**
- * Renders FFT magnitude as vertical bars.
- *
- * The input is the raw FFT byte array from Visualizer where values are interleaved
- * real and imaginary parts: [re0, im0, re1, im1, ...]. This composable computes the
- * magnitude per bin and draws a limited number of bars for readability.
- *
- * @param data Interleaved real/imag FFT bytes; null shows a baseline.
- * @param modifier Compose modifier for sizing and padding.
- */
-@Composable
-fun FftBarsView(
-    data: ByteArray?,
-    modifier: Modifier = Modifier,
-) {
-    Text("FFT (magnitude bars)", style = MaterialTheme.typography.titleMedium)
-    Canvas(
-        modifier = modifier
-            .fillMaxWidth()
-            .height(160.dp)
-            .padding(vertical = 4.dp)
-    ) {
-        val w = size.width
-        val h = size.height
-        if (data != null && data.size >= 2) {
-            val n = data.size / 2 // real/imag pairs count
-            val barCount = min(64, n) // limit bars for readability
-            val barWidth = w / barCount
-            for (i in 0 until barCount) {
-                val re = data[2 * i].toInt()
-                val im = data[2 * i + 1].toInt()
-                val mag = hypot(re.toDouble(), im.toDouble()).toFloat()
-                val scaled = (mag / 128f).coerceIn(0f, 1.5f)
-                val barHeight = h * (scaled.coerceAtMost(1f))
-                val left = i * barWidth
-                drawRect(
-                    color = Color(0xFF8BC34A),
-                    topLeft = androidx.compose.ui.geometry.Offset(left, h - barHeight),
-                    size = androidx.compose.ui.geometry.Size(barWidth * 0.9f, barHeight)
-                )
-            }
-        } else {
-            drawLine(
-                color = Color.Gray,
-                start = androidx.compose.ui.geometry.Offset(0f, h - 1f),
-                end = androidx.compose.ui.geometry.Offset(w, h - 1f),
-                strokeWidth = 1f
-            )
-        }
-    }
-}

app/src/main/java/dev/adriankuta/visualizer/components/MetricsSection.kt

@@ -1,74 +0,0 @@
-package dev.adriankuta.visualizer.components
-
-import androidx.compose.foundation.layout.Arrangement
-import androidx.compose.foundation.layout.Column
-import androidx.compose.foundation.layout.Row
-import androidx.compose.foundation.layout.fillMaxWidth
-import androidx.compose.foundation.layout.height
-import androidx.compose.foundation.layout.padding
-import androidx.compose.material3.MaterialTheme
-import androidx.compose.material3.Text
-import androidx.compose.runtime.Composable
-import androidx.compose.ui.Modifier
-import androidx.compose.ui.unit.dp
-import kotlin.math.abs
-
-/**
- * Displays simple metrics derived from the current waveform and a preview of raw bytes.
- *
- * - Waveform metrics include sample count, RMS and peak (centered around 128).
- * - Raw bytes shows the first N bytes from waveform or FFT, whichever is available.
- *
- * @param waveform Latest waveform bytes (0..255 per sample) or null if not available.
- * @param fft Latest FFT interleaved real/imag bytes or null.
- * @param modifier Compose modifier for layout.
- */
-@Composable
-fun MetricsSection(
-    waveform: ByteArray?,
-    fft: ByteArray?,
-    modifier: Modifier = Modifier,
-) {
-    Row(modifier = modifier.fillMaxWidth(), horizontalArrangement = Arrangement.SpaceBetween) {
-        Column(modifier = Modifier.weight(1f)) {
-            Text("Waveform metrics", style = MaterialTheme.typography.titleSmall)
-            val wf = waveform
-            if (wf != null) {
-                val rms = rms(wf)
-                val peak = peak(wf)
-                Text("Samples: ${wf.size}")
-                Text("RMS: ${String.format("%.3f", rms)}")
-                Text("Peak: ${String.format("%.3f", peak)}")
-            } else {
-                Text("No waveform yet")
-            }
-        }
-        Column(modifier = Modifier.weight(1f)) {
-            Text("Raw bytes (first 32)", style = MaterialTheme.typography.titleSmall)
-            val arr = waveform ?: fft
-            Text(arr?.let { firstBytesString(it, 32) } ?: "<no data>")
-        }
-    }
-}
-
-private fun firstBytesString(bytes: ByteArray, count: Int): String =
-    bytes.take(count).joinToString(prefix = "[", postfix = "]") { it.toUByte().toString() }
-
-private fun rms(bytes: ByteArray): Double {
-    if (bytes.isEmpty()) return 0.0
-    var sum = 0.0
-    for (b in bytes) {
-        val centered = (b.toInt() and 0xFF) - 128
-        sum += centered * centered
-    }
-    return kotlin.math.sqrt(sum / bytes.size)
-}
-
-private fun peak(bytes: ByteArray): Double {
-    var p = 0
-    for (b in bytes) {
-        val centered = abs(((b.toInt() and 0xFF) - 128))
-        if (centered > p) p = centered
-    }
-    return p.toDouble()
-}

app/src/main/java/dev/adriankuta/visualizer/components/PermissionSection.kt

@@ -1,33 +0,0 @@
-package dev.adriankuta.visualizer.components
-
-import android.Manifest
-import androidx.compose.foundation.layout.Spacer
-import androidx.compose.foundation.layout.height
-import androidx.compose.material3.Button
-import androidx.compose.material3.MaterialTheme
-import androidx.compose.material3.Text
-import androidx.compose.runtime.Composable
-import androidx.compose.ui.Modifier
-import androidx.compose.ui.unit.dp
-import androidx.activity.compose.ManagedActivityResultLauncher
-
-/**
- * Shows rationale and a button to request RECORD_AUDIO permission when not granted.
- *
- * @param permissionGranted Whether microphone permission is already granted.
- * @param requestPermissionLauncher Launcher configured for ActivityResultContracts.RequestPermission().
- * @param modifier Compose modifier for layout.
- */
-@Composable
-fun PermissionSection(
-    permissionGranted: Boolean,
-    requestPermissionLauncher: ManagedActivityResultLauncher<String, Boolean>,
-    modifier: Modifier = Modifier,
-) {
-    if (permissionGranted) return
-    Text("This app needs microphone permission to access the audio output for visualization.", style = MaterialTheme.typography.bodyMedium)
-    Spacer(Modifier.height(8.dp))
-    Button(onClick = { requestPermissionLauncher.launch(Manifest.permission.RECORD_AUDIO) }) {
-        Text("Grant Microphone Permission")
-    }
-}

app/src/main/java/dev/adriankuta/visualizer/components/WaveformView.kt

@@ -1,62 +0,0 @@
-package dev.adriankuta.visualizer.components
-
-import androidx.compose.foundation.Canvas
-import androidx.compose.foundation.layout.fillMaxWidth
-import androidx.compose.foundation.layout.height
-import androidx.compose.foundation.layout.padding
-import androidx.compose.material3.MaterialTheme
-import androidx.compose.material3.Text
-import androidx.compose.runtime.Composable
-import androidx.compose.ui.Modifier
-import androidx.compose.ui.graphics.Color
-import androidx.compose.ui.graphics.Path
-import androidx.compose.ui.graphics.drawscope.Stroke
-import androidx.compose.ui.unit.dp
-
-/**
- * Displays the most recent audio waveform as a continuous path.
- *
- * @param data Waveform bytes where each value is 0..255 (unsigned), as provided by Visualizer.
- *             Pass null to render an idle baseline.
- * @param modifier Compose modifier for sizing and padding.
- */
-@Composable
-fun WaveformView(
-    data: ByteArray?,
-    modifier: Modifier = Modifier,
-) {
-    Text("Waveform", style = MaterialTheme.typography.titleMedium)
-    Canvas(
-        modifier = modifier
-            .fillMaxWidth()
-            .height(120.dp)
-            .padding(vertical = 4.dp)
-    ) {
-        val w = size.width
-        val h = size.height
-        if (data == null || data.isEmpty()) {
-            drawLine(
-                color = Color.Gray,
-                start = androidx.compose.ui.geometry.Offset(0f, h / 2),
-                end = androidx.compose.ui.geometry.Offset(w, h / 2),
-                strokeWidth = 1f
-            )
-        } else {
-            val path = Path()
-            val stepX = w / (data.size - 1).coerceAtLeast(1)
-            for (i in data.indices) {
-                val x = i * stepX
-                val normalized = (data[i].toInt() and 0xFF) / 255f
-                val y = h * (1f - normalized)
-                if (i == 0) path.moveTo(x, y) else path.lineTo(x, y)
-            }
-            drawPath(path = path, color = Color.Cyan, style = Stroke(width = 2f))
-            drawLine(
-                color = Color.Gray,
-                start = androidx.compose.ui.geometry.Offset(0f, h / 2),
-                end = androidx.compose.ui.geometry.Offset(w, h / 2),
-                strokeWidth = 1f
-            )
-        }
-    }
-}

app/src/main/java/dev/adriankuta/visualizer/data/AudioVisualizer.kt

@@ -0,0 +1,9 @@
+package dev.adriankuta.visualizer.data
+
+import kotlinx.coroutines.flow.Flow
+
+interface AudioVisualizer: AudioVisualizerController {
+    fun waveform(): Flow<WaveformFrame>
+
+    fun fft(): Flow<FftFrame>
+}

app/src/main/java/dev/adriankuta/visualizer/data/AudioVisualizerController.kt

@@ -0,0 +1,8 @@
+package dev.adriankuta.visualizer.data
+
+interface AudioVisualizerController {
+
+    fun start()
+
+    fun stop()
+}

app/src/main/java/dev/adriankuta/visualizer/data/AudioVisualizerImpl.kt

@@ -0,0 +1,75 @@
+package dev.adriankuta.visualizer.data
+
+import android.media.audiofx.Visualizer
+import kotlinx.coroutines.channels.awaitClose
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.callbackFlow
+import kotlinx.coroutines.flow.conflate
+import kotlinx.coroutines.flow.filterIsInstance
+import javax.inject.Inject
+
+class AudioVisualizerImpl @Inject constructor(
+    private val visualizer: Visualizer
+) : AudioVisualizer {
+
+    override fun start() {
+        visualizer.enabled = true
+    }
+
+    override fun stop() {
+        visualizer.enabled = false
+    }
+
+    override fun waveform(): Flow<WaveformFrame> =
+        visualizerFlow()
+            .filterIsInstance(WaveformFrame::class)
+
+    override fun fft(): Flow<FftFrame> =
+        visualizerFlow()
+            .filterIsInstance(FftFrame::class)
+
+    private fun visualizerFlow(): Flow<VisualizerFrame> = callbackFlow {
+        val listener = object : Visualizer.OnDataCaptureListener {
+            override fun onFftDataCapture(
+                visualizer: Visualizer?,
+                fft: ByteArray,
+                samplingRate: Int
+            ) {
+                trySend(FftFrame(fft.copyOf()))
+            }
+
+            override fun onWaveFormDataCapture(
+                visualizer: Visualizer?,
+                waveform: ByteArray,
+                samplingRate: Int
+            ) {
+                trySend(WaveformFrame(waveform.copyOf()))
+            }
+        }
+
+        visualizer.setDataCaptureListener(
+            listener,
+            Visualizer.getMaxCaptureRate(),
+            true,
+            true
+        )
+
+        awaitClose {
+            runCatching {
+                visualizer.enabled = false
+                visualizer.setDataCaptureListener(null, 0, false, false)
+                visualizer.release()
+            }
+        }
+    }
+        .conflate()
+}
+
+sealed interface VisualizerFrame
+data class WaveformFrame(
+    val data: ByteArray,
+) : VisualizerFrame
+
+data class FftFrame(
+    val data: ByteArray,
+) : VisualizerFrame

app/src/main/java/dev/adriankuta/visualizer/di/VisualizerModule.kt

@@ -0,0 +1,37 @@
+package dev.adriankuta.visualizer.di
+
+import android.media.audiofx.Visualizer
+import dagger.Binds
+import dagger.Module
+import dagger.Provides
+import dagger.hilt.InstallIn
+import dagger.hilt.components.SingletonComponent
+import dev.adriankuta.visualizer.data.AudioVisualizer
+import dev.adriankuta.visualizer.data.AudioVisualizerController
+import dev.adriankuta.visualizer.data.AudioVisualizerImpl
+import javax.inject.Singleton
+
+@Module
+@InstallIn(SingletonComponent::class)
+abstract class VisualizerModule {
+
+    @Binds
+    abstract fun bindVisualizer(
+        audioVisualizerImpl: AudioVisualizerImpl
+    ): AudioVisualizer
+
+    @Binds
+    abstract fun bindVisualizerToController(
+        audioVisualizerImpl: AudioVisualizerImpl
+    ): AudioVisualizerController
+
+    companion object {
+        @Provides
+        @Singleton
+        fun provideVisualizer(): Visualizer {
+            return Visualizer(0).apply {
+                captureSize = 1024
+            }
+        }
+    }
+}

app/src/main/java/dev/adriankuta/visualizer/domain/ObserveVisualizerColorUseCase.kt

@@ -0,0 +1,23 @@
+package dev.adriankuta.visualizer.domain
+
+import androidx.compose.ui.graphics.Color
+import dev.adriankuta.visualizer.data.AudioVisualizer
+import dev.adriankuta.visualizer.data.WaveformFrame
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.map
+import javax.inject.Inject
+
+class ObserveVisualizerColorUseCase @Inject constructor(
+    private val audioVisualizer: AudioVisualizer
+) {
+
+    private val colorMapper = HSLSoundToColorMapper()
+
+    operator fun invoke(): Flow<Color> =
+        audioVisualizer.waveform()
+            .map { processColor(it) }
+
+    private fun processColor(waveformFrame: WaveformFrame): Color {
+        return colorMapper.mapSoundToColor(waveformFrame.data)
+    }
+}

app/src/main/java/dev/adriankuta/visualizer/domain/SoundToColorMapper.kt

@@ -0,0 +1,97 @@
+package dev.adriankuta.visualizer.domain
+
+import androidx.compose.ui.graphics.Color
+import dev.adriankuta.visualizer.HSL
+import dev.adriankuta.visualizer.MovingAverage
+import dev.adriankuta.visualizer.calculateRms
+
+/**
+ * Interface for mapping sound data to colors.
+ * Follows the Interface Segregation Principle by defining a focused contract.
+ */
+interface SoundToColorMapper {
+    /**
+     * Maps audio waveform data to a color.
+     * 
+     * @param waveform Audio waveform data as byte array
+     * @return Compose Color representing the mapped sound
+     */
+    fun mapSoundToColor(waveform: ByteArray): Color
+    
+    /**
+     * Resets the internal state of the mapper.
+     */
+    fun reset()
+}
+
+/**
+ * Default implementation of SoundToColorMapper that uses HSL color space
+ * and moving average for smooth color transitions.
+ * 
+ * Follows Single Responsibility Principle by focusing on sound-to-color mapping.
+ * Follows Dependency Inversion Principle by depending on abstractions.
+ */
+class HSLSoundToColorMapper(
+    private val baseHue: Float = 0f, // Blue hue as default
+    private val saturation: Float = 1f,
+    private val movingAverageWindowSize: Int = 1
+) : SoundToColorMapper {
+    
+    private val movingAverage = MovingAverage(movingAverageWindowSize)
+    private var rmsMax = 0.0
+    
+    override fun mapSoundToColor(waveform: ByteArray): Color {
+        // Calculate RMS value for current frame
+        val currentRms = calculateRms(waveform)
+        
+        // Update maximum RMS value for normalization
+        if (currentRms > rmsMax) {
+            rmsMax = currentRms
+        }
+        
+        // Calculate energy ratio (0-1)
+        val energyRatio = if (rmsMax > 0) currentRms / rmsMax else 0.0
+        
+        // Apply moving average for smooth transitions
+        val adjustedLightness = movingAverage.process(energyRatio)
+        
+        // Create HSL color and convert to Compose Color
+        val hslColor = HSL(
+            hue = baseHue,
+            saturation = saturation,
+            lightness = adjustedLightness.toFloat().coerceIn(0f, 1f)
+        )
+        
+        return hslColor.toComposeColor()
+    }
+    
+    override fun reset() {
+        movingAverage.reset()
+        rmsMax = 0.0
+    }
+}
+
+/**
+ * Factory for creating SoundToColorMapper instances.
+ * Follows the Factory Pattern and Open/Closed Principle.
+ */
+object SoundToColorMapperFactory {
+    
+    /**
+     * Creates a default HSL-based sound to color mapper.
+     */
+    fun createDefault(): SoundToColorMapper = HSLSoundToColorMapper()
+    
+    /**
+     * Creates an HSL-based sound to color mapper with custom parameters.
+     * 
+     * @param baseHue The base hue for the color (0-360)
+     * @param saturation The saturation level (0-1)
+     * @param movingAverageWindowSize Window size for moving average smoothing
+     */
+    fun createHSLMapper(
+        baseHue: Float = 240f,
+        saturation: Float = 1f,
+        movingAverageWindowSize: Int = 7
+    ): SoundToColorMapper = HSLSoundToColorMapper(baseHue, saturation, movingAverageWindowSize)
+}

app/src/main/java/dev/adriankuta/visualizer/domain/VisualizerState.kt

@@ -0,0 +1,91 @@
+package dev.adriankuta.visualizer.domain
+
+import android.graphics.Color
+import kotlin.math.*
+
+// Keep this across frames (e.g., one per audio stream/visualizer)
+data class VisualizerState(
+    var prevMag: FloatArray? = null,
+    var maxEnergy: Double = 1e-6,  // running max of energy
+    var maxFlux: Double = 1e-6     // running max of flux
+)
+
+/**
+ * Convert one FFT magnitude spectrum to a color.
+ *
+ * @param mags        Magnitude of the *half* spectrum (bins 0..Nyquist), non-negative.
+ * @param sampleRate  Audio sample rate in Hz (e.g., 44100).
+ * @param state       Persistent state for normalization & flux (keep between calls).
+ * @return            ARGB color Int (Android).
+ */
+fun fftToColor(mags: FloatArray, sampleRate: Int, state: VisualizerState): Int {
+    require(mags.isNotEmpty()) { "mags must not be empty" }
+    val nBins = mags.size
+    val nyquist = sampleRate * 0.5
+
+    // --- Basic spectrum stats ---
+    var sumMag = 0.0
+    var weightedFreqSum = 0.0
+    var energy = 0.0
+
+    // Frequency step per bin (covers 0..Nyquist across nBins bins)
+    val binHz = if (nBins > 1) nyquist / (nBins - 1) else 0.0
+
+    for (k in 0 until nBins) {
+        val m = mags[k].toDouble().coerceAtLeast(0.0)
+        sumMag += m
+        energy += m * m
+        val fk = k * binHz
+        weightedFreqSum += fk * m
+    }
+
+    // Spectral centroid in Hz (fallback to 0 when silent)
+    val centroidHz = if (sumMag > 0.0) weightedFreqSum / sumMag else 0.0
+
+    // Log-scaled centroid -> [0,1] (more perceptual)
+    val hue01 = run {
+        val num = ln(1.0 + centroidHz)
+        val den = ln(1.0 + nyquist)
+        if (den > 0.0) (num / den).coerceIn(0.0, 1.0) else 0.0
+    }
+
+    // --- Spectral flux (vs. previous frame) for saturation ---
+    val prev = state.prevMag
+    var flux = 0.0
+    if (prev != null && prev.size == nBins) {
+        for (k in 0 until nBins) {
+            val d = mags[k].toDouble() - prev[k].toDouble()
+            if (d > 0.0) flux += d
+        }
+    }
+    // Update prev spectrum (copy to avoid aliasing)
+    state.prevMag = mags.copyOf()
+
+    // --- Adaptive normalization (with slow decay) ---
+    // Update running maxima with slight decay so the visual doesn't "stick"
+    fun decay(x: Double, factor: Double) = x * factor
+
+    state.maxEnergy = max(decay(state.maxEnergy, 0.995), energy)
+    state.maxFlux   = max(decay(state.maxFlux,   0.995), flux)
+
+    // --- Map to HSV ---
+    // V: log-compress energy; normalize by running max
+    val v = run {
+        val eNorm = if (state.maxEnergy > 1e-12) energy / state.maxEnergy else 0.0
+        val logCompressed = ln(1.0 + 9.0 * eNorm) / ln(10.0) // [0,1], gentle curve
+        logCompressed.coerceIn(0.0, 1.0)
+    }
+
+    // S: flux normalized by running max, then soft knee
+    val s = run {
+        val fNorm = if (state.maxFlux > 1e-12) flux / state.maxFlux else 0.0
+        val soft = sqrt(fNorm.coerceIn(0.0, 1.0)) // emphasizes small changes less
+        (0.15 + 0.85 * soft).coerceIn(0.0, 1.0)   // keep some color even when still
+    }
+
+    // H: map [0,1] over a 300° range so it wraps nicely (0=red, 0.5≈cyan, 1≈purple)
+    val h = (hue01 * 300.0).toFloat()
+
+    val hsv = floatArrayOf(h, s.toFloat(), v.toFloat())
+    return Color.HSVToColor(hsv) // ARGB Int
+}

app/src/main/java/dev/adriankuta/visualizer/kotlin_code_one_color.txt

@@ -0,0 +1,99 @@
+import kotlin.math.sqrt
+
+data class HSL(
+// in Python code, the HSL values were in range 0 - 1
+
+    val hue: Float,
+    val saturation: Float,
+    val lightness: Float
+) {
+    fun toRgb(): Triple<Int, Int, Int> {
+        val (r, g, b) = hlsToRgb(hue / 360, lightness, saturation) // Convert HSL to RGB
+        return Triple((r * 255).toInt(), (g * 255).toInt(), (b * 255).toInt())
+    }
+
+    private fun hlsToRgb(h: Float, l: Float, s: Float): Triple<Float, Float, Float> {
+        val r: Float
+        val g: Float
+        val b: Float
+
+        if (s == 0f) {
+            // Achromatic (gray)
+            r = l
+            g = l
+            b = l
+        } else {
+            val q = if (l < 0.5) l * (1 + s) else l + s - l * s
+            val p = 2 * l - q
+
+            r = hueToRgb(p, q, h + 1 / 3)
+            g = hueToRgb(p, q, h)
+            b = hueToRgb(p, q, h - 1 / 3)
+        }
+
+        return Triple(r, g, b)
+    }
+
+    private fun hueToRgb(p: Float, q: Float, t: Float): Float {
+        var tTemp = t
+        if (tTemp < 0) tTemp += 1
+        if (tTemp > 1) tTemp -= 1
+        return when {
+            tTemp < 1 / 6 -> p + (q - p) * 6 * tTemp
+            tTemp < 1 / 2 -> q
+            tTemp < 2 / 3 -> p + (q - p) * (2 / 3 - tTemp) * 6
+            else -> p
+        }
+    }
+}
+
+// copied from Adrian's code, so this probably redundant here
+private fun rms(bytes: ByteArray): Double {
+    if (bytes.isEmpty()) return 0.0
+    var sum = 0.0
+    for (b in bytes) {
+        val centered = (b.toInt() and 0xFF) - 128
+        sum += centered * centered
+    }
+    return kotlin.math.sqrt(sum / bytes.size)
+}
+
+
+// not sure whether the rmsMax, movingAverage, and hslColor should be passed as parameter, therefore I used  "...", in Python they were all: self.rms_max, ... so I could access them directly
+fun soundToColor( ... ) {
+	// Time domain processing, adjustable maximum of energy (we need ratio, as we do not have given maximum)
+    	
+	// calculate RMS value for one current frame, actualize value of RMS maximum
+	val tmpRms = rms(wf)		// variable "wf" - waveform, I saw it Adrian's code
+	if (tmpRms > rmsMax) {
+		rmsMax = tmpRms
+	}
+	energyRatio = tmpRms / rmsMax
+    adjLightness = movingAverage.process(energyRatio)
+	hslColor.lightness = adjLightness
+	val rgbColor = hslColor.toRgb()
+	return rgbColor
+}
+
+
+
+// predefine values for soundToColor method
+val movingAverage = MovingAverage(windowSize = 7)	// object for calculation of moving average, this should stay the same during the run of application
+rmsMax = 0.0		// to store the value of current maximum of RMS, this might be changed in every call of method (every loop)
+val hslColor = HSL(hue = 0f, saturation = 1f, value = 0f)	// to store the values for current color, value will change every loop
+
+
+// I can only gues, but I can imagine that the definitioin of variables (movingAverage, rmsMax, hslColor) can be defined
+// somewhere at higher level of application, maybe VisualizerScreen.
+// Somewhere, where the loop that takes data for waveform, where the data can be passed to soundToColor.
+//
+// And as I do not know Kotlin, I am not able to tell how it should be there.
+// Then, the method soundToColor might be defined (implemented) in MetricsSection, with the rest of the code too.
+// Or is it for separate file?
+//
+// I can only gues how it will work. In Python, the settigns of audio processing was:
+// sampling_rate = 16000 # Hz, sampling frequency
+// window_size = 1024
+// moving averate size = 7
+//
+// I think that, when the window size (or sampling rate) is different we will need to find new value for moving average

app/src/main/java/dev/adriankuta/visualizer/view/VisualizerScreen.kt

@@ -0,0 +1,300 @@
+package dev.adriankuta.visualizer.view
+
+import android.Manifest
+import android.content.pm.PackageManager
+import androidx.activity.compose.rememberLauncherForActivityResult
+import androidx.activity.result.contract.ActivityResultContracts
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.*
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.material3.*
+import androidx.compose.runtime.*
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.clip
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.text.style.TextAlign
+import androidx.compose.ui.unit.dp
+import androidx.compose.ui.unit.sp
+import androidx.core.content.ContextCompat
+import androidx.hilt.navigation.compose.hiltViewModel
+import androidx.lifecycle.Lifecycle
+import androidx.lifecycle.LifecycleEventObserver
+import androidx.lifecycle.compose.LocalLifecycleOwner
+import androidx.lifecycle.compose.collectAsStateWithLifecycle
+import dev.adriankuta.visualizer.AudioVisualizerFactory
+import dev.adriankuta.visualizer.AudioVisualizerService
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.SupervisorJob
+import timber.log.Timber
+
+
+@Composable
+fun VisualizerScreen(
+    viewModel: VisualizerScreenViewModel = hiltViewModel()
+) {
+
+    val uiState by viewModel.uiState.collectAsStateWithLifecycle()
+
+}
+@Composable
+fun VisualizerScreen(
+    modifier: Modifier = Modifier,
+    audioVisualizer: AudioVisualizerService = remember {
+        AudioVisualizerFactory.createDefault(
+            CoroutineScope(Dispatchers.Main + SupervisorJob())
+        )
+    }
+) {
+    val context = LocalContext.current
+    val lifecycleOwner = LocalLifecycleOwner.current
+    val currentColor by audioVisualizer.currentColor
+    val isActive by audioVisualizer.isActive
+
+    // Permission state management
+    var hasAudioPermission by remember {
+        mutableStateOf(
+            ContextCompat.checkSelfPermission(
+                context,
+                Manifest.permission.RECORD_AUDIO
+            ) == PackageManager.PERMISSION_GRANTED
+        )
+    }
+
+    var showPermissionRationale by remember { mutableStateOf(false) }
+
+    // Permission request launcher
+    val permissionLauncher = rememberLauncherForActivityResult(
+        contract = ActivityResultContracts.RequestPermission()
+    ) { isGranted ->
+        hasAudioPermission = isGranted
+        if (isGranted) {
+            Timber.d("Audio permission granted, starting visualizer")
+            audioVisualizer.start()
+        } else {
+            Timber.w("Audio permission denied")
+            showPermissionRationale = true
+        }
+    }
+
+    // Function to start audio visualizer with permission check
+    fun startVisualizerWithPermissionCheck() {
+        when {
+            hasAudioPermission -> {
+                audioVisualizer.start()
+            }
+            else -> {
+                Timber.d("Requesting audio permission")
+                permissionLauncher.launch(Manifest.permission.RECORD_AUDIO)
+            }
+        }
+    }
+
+    // Handle lifecycle events
+    DisposableEffect(lifecycleOwner) {
+        val observer = LifecycleEventObserver { _, event ->
+            when (event) {
+                Lifecycle.Event.ON_START -> startVisualizerWithPermissionCheck()
+                Lifecycle.Event.ON_STOP -> audioVisualizer.stop()
+                else -> {}
+            }
+        }
+
+        lifecycleOwner.lifecycle.addObserver(observer)
+
+        onDispose {
+            lifecycleOwner.lifecycle.removeObserver(observer)
+            audioVisualizer.release()
+        }
+    }
+
+    Column(
+        modifier = modifier
+            .fillMaxSize()
+            .padding(16.dp),
+        horizontalAlignment = Alignment.CenterHorizontally,
+        verticalArrangement = Arrangement.Center
+    ) {
+        // Title
+        Text(
+            text = "Audio Color Visualizer",
+            fontSize = 24.sp,
+            fontWeight = FontWeight.Bold,
+            textAlign = TextAlign.Center,
+            modifier = Modifier.padding(bottom = 32.dp)
+        )
+
+        // Color display area
+        Box(
+            modifier = Modifier
+                .size(300.dp)
+                .clip(RoundedCornerShape(16.dp))
+                .background(currentColor)
+                .padding(16.dp),
+            contentAlignment = Alignment.Center
+        ) {
+            // Show color information
+            ColorInfoCard(
+                color = currentColor,
+                isActive = isActive
+            )
+        }
+
+        Spacer(modifier = Modifier.height(32.dp))
+
+        // Status indicator
+        StatusIndicator(
+            isActive = isActive,
+            hasPermission = hasAudioPermission
+        )
+
+        Spacer(modifier = Modifier.height(16.dp))
+
+        // Instructions
+        Text(
+            text = when {
+                !hasAudioPermission -> "Audio permission is required to visualize sound"
+                isActive -> "Play some music or make sounds to see the colors change!"
+                else -> "Starting audio visualizer..."
+            },
+            fontSize = 16.sp,
+            textAlign = TextAlign.Center,
+            color = MaterialTheme.colorScheme.onSurfaceVariant,
+            modifier = Modifier.padding(horizontal = 32.dp)
+        )
+
+        // Permission request button (shown when permission is denied)
+        if (!hasAudioPermission) {
+            Spacer(modifier = Modifier.height(16.dp))
+
+            Button(
+                onClick = {
+                    showPermissionRationale = false
+                    permissionLauncher.launch(Manifest.permission.RECORD_AUDIO)
+                },
+                modifier = Modifier.padding(horizontal = 32.dp)
+            ) {
+                Text("Grant Audio Permission")
+            }
+        }
+    }
+
+    // Permission rationale dialog
+    if (showPermissionRationale) {
+        AlertDialog(
+            onDismissRequest = { showPermissionRationale = false },
+            title = { Text("Audio Permission Required") },
+            text = { 
+                Text("This app needs access to your microphone to visualize audio and create colors based on sound. Please grant the audio recording permission to continue.")
+            },
+            confirmButton = {
+                TextButton(
+                    onClick = {
+                        showPermissionRationale = false
+                        permissionLauncher.launch(Manifest.permission.RECORD_AUDIO)
+                    }
+                ) {
+                    Text("Grant Permission")
+                }
+            },
+            dismissButton = {
+                TextButton(
+                    onClick = { showPermissionRationale = false }
+                ) {
+                    Text("Cancel")
+                }
+            }
+        )
+    }
+}
+
+/**
+ * Card displaying color information.
+ */
+@Composable
+private fun ColorInfoCard(
+    color: Color,
+    isActive: Boolean,
+    modifier: Modifier = Modifier
+) {
+    Card(
+        modifier = modifier,
+        colors = CardDefaults.cardColors(
+            containerColor = Color.White.copy(alpha = 0.9f)
+        ),
+        elevation = CardDefaults.cardElevation(defaultElevation = 4.dp)
+    ) {
+        Column(
+            modifier = Modifier.padding(16.dp),
+            horizontalAlignment = Alignment.CenterHorizontally
+        ) {
+            Text(
+                text = "Current Color",
+                fontSize = 14.sp,
+                fontWeight = FontWeight.Medium,
+                color = Color.Black
+            )
+
+            Spacer(modifier = Modifier.height(8.dp))
+
+            // RGB values
+            val (r, g, b) = with(color) {
+                Triple(
+                    (red * 255).toInt(),
+                    (green * 255).toInt(),
+                    (blue * 255).toInt()
+                )
+            }
+
+            Text(
+                text = "RGB($r, $g, $b)",
+                fontSize = 12.sp,
+                color = Color.Black.copy(alpha = 0.7f),
+                fontWeight = FontWeight.Light
+            )
+        }
+    }
+}
+
+/**
+ * Status indicator showing whether the visualizer is active and permission status.
+ */
+@Composable
+private fun StatusIndicator(
+    isActive: Boolean,
+    hasPermission: Boolean,
+    modifier: Modifier = Modifier
+) {
+    Row(
+        modifier = modifier,
+        verticalAlignment = Alignment.CenterVertically
+    ) {
+        Box(
+            modifier = Modifier
+                .size(12.dp)
+                .clip(RoundedCornerShape(6.dp))
+                .background(
+                    when {
+                        !hasPermission -> Color.Gray
+                        isActive -> Color.Green
+                        else -> Color.Red
+                    }
+                )
+        )
+
+        Spacer(modifier = Modifier.width(8.dp))
+
+        Text(
+            text = when {
+                !hasPermission -> "Permission Required"
+                isActive -> "Active"
+                else -> "Inactive"
+            },
+            fontSize = 14.sp,
+            color = MaterialTheme.colorScheme.onSurface
+        )
+    }
+}

app/src/main/java/dev/adriankuta/visualizer/view/VisualizerScreenUiState.kt

@@ -0,0 +1,7 @@
+package dev.adriankuta.visualizer.view
+
+import androidx.compose.ui.graphics.Color
+
+data class VisualizerScreenUiState(
+    val color: Color
+)

app/src/main/java/dev/adriankuta/visualizer/view/VisualizerScreenViewModel.kt

@@ -0,0 +1,23 @@
+package dev.adriankuta.visualizer.view
+
+import androidx.compose.ui.graphics.Color
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import dagger.hilt.android.lifecycle.HiltViewModel
+import dev.adriankuta.visualizer.domain.ObserveVisualizerColorUseCase
+import kotlinx.coroutines.flow.SharingStarted
+import kotlinx.coroutines.flow.stateIn
+import javax.inject.Inject
+
+@HiltViewModel
+class VisualizerScreenViewModel @Inject constructor(
+    private val observeVisualizerColorUseCase: ObserveVisualizerColorUseCase
+) : ViewModel() {
+
+    val uiState = observeVisualizerColorUseCase()
+        .stateIn(
+            scope = viewModelScope,
+            started = SharingStarted.WhileSubscribed(5_000),
+            initialValue = Color.Black
+        )
+}

build.gradle.kts

@@ -3,4 +3,6 @@ plugins {
     alias(libs.plugins.android.application) apply false
     alias(libs.plugins.kotlin.android) apply false
     alias(libs.plugins.kotlin.compose) apply false
+    alias(libs.plugins.hilt.android) apply false
+    alias(libs.plugins.google.ksp) apply false
 }

gradle/libs.versions.toml

@@ -1,18 +1,24 @@
 [versions]
-agp = "8.11.1"
+activityCompose = "1.11.0"
-kotlin = "2.2.10"
+agp = "8.11.2"
+composeBom = "2025.09.01"
 coreKtx = "1.17.0"
+coroutines = "1.10.2"
+espressoCore = "3.7.0"
+hilt = "2.57.2"
+hiltNavigationCompose = "1.2.0"
 junit = "4.13.2"
 junitVersion = "1.3.0"
-espressoCore = "3.7.0"
+kotlin = "2.2.20"
-lifecycleRuntimeKtx = "2.9.3"
+ksp = "2.2.20-2.0.3"
-activityCompose = "1.10.1"
+lifecycleRuntimeKtx = "2.9.4"
-composeBom = "2025.08.01"
 timber = "5.0.1"
-coroutines = "1.8.0"
 
 [libraries]
 androidx-core-ktx = { group = "androidx.core", name = "core-ktx", version.ref = "coreKtx" }
+androidx-hilt-navigation-compose = { group = "androidx.hilt", name = "hilt-navigation-compose", version.ref = "hiltNavigationCompose" }
+hilt-android-compiler = { module = "com.google.dagger:hilt-android-compiler", version.ref = "hilt" }
+hilt-android = { module = "com.google.dagger:hilt-android", version.ref = "hilt" }
 junit = { group = "junit", name = "junit", version.ref = "junit" }
 androidx-junit = { group = "androidx.test.ext", name = "junit", version.ref = "junitVersion" }
 androidx-espresso-core = { group = "androidx.test.espresso", name = "espresso-core", version.ref = "espressoCore" }
@@ -33,3 +39,5 @@ kotlinx-coroutines-android = { group = "org.jetbrains.kotlinx", name = "kotlinx-
 android-application = { id = "com.android.application", version.ref = "agp" }
 kotlin-android = { id = "org.jetbrains.kotlin.android", version.ref = "kotlin" }
 kotlin-compose = { id = "org.jetbrains.kotlin.plugin.compose", version.ref = "kotlin" }
+hilt-android = {id = "com.google.dagger.hilt.android", version.ref = "hilt" }
+google-ksp = { id = "com.google.devtools.ksp", version.ref = "ksp" }