first commit

2025-08-29 11:47:23 +02:00
commit 2a46c6143b
58 changed files with 2925 additions and 0 deletions
--- a/app/.gitignore
+++ b/app/.gitignore
@@ -0,0 +1 @@
+/build
--- a/app/build.gradle.kts
+++ b/app/build.gradle.kts
@@ -0,0 +1,59 @@
+plugins {
+    alias(libs.plugins.android.application)
+    alias(libs.plugins.kotlin.android)
+    alias(libs.plugins.kotlin.compose)
+}
+
+android {
+    namespace = "dev.adriankuta.visualizer"
+    compileSdk = 36
+
+    defaultConfig {
+        applicationId = "dev.adriankuta.visualizer"
+        minSdk = 24
+        targetSdk = 36
+        versionCode = 1
+        versionName = "1.0"
+
+        testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
+    }
+
+    buildTypes {
+        release {
+            isMinifyEnabled = false
+            proguardFiles(
+                getDefaultProguardFile("proguard-android-optimize.txt"),
+                "proguard-rules.pro"
+            )
+        }
+    }
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_11
+        targetCompatibility = JavaVersion.VERSION_11
+    }
+    kotlinOptions {
+        jvmTarget = "11"
+    }
+    buildFeatures {
+        compose = true
+    }
+}
+
+dependencies {
+
+    implementation(libs.androidx.core.ktx)
+    implementation(libs.androidx.lifecycle.runtime.ktx)
+    implementation(libs.androidx.activity.compose)
+    implementation(platform(libs.androidx.compose.bom))
+    implementation(libs.androidx.compose.ui)
+    implementation(libs.androidx.compose.ui.graphics)
+    implementation(libs.androidx.compose.ui.tooling.preview)
+    implementation(libs.androidx.compose.material3)
+    testImplementation(libs.junit)
+    androidTestImplementation(libs.androidx.junit)
+    androidTestImplementation(libs.androidx.espresso.core)
+    androidTestImplementation(platform(libs.androidx.compose.bom))
+    androidTestImplementation(libs.androidx.compose.ui.test.junit4)
+    debugImplementation(libs.androidx.compose.ui.tooling)
+    debugImplementation(libs.androidx.compose.ui.test.manifest)
+}
--- a/app/proguard-rules.pro
+++ b/app/proguard-rules.pro
@@ -0,0 +1,21 @@
+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile
--- a/app/src/androidTest/java/dev/adriankuta/visualizer/ExampleInstrumentedTest.kt
+++ b/app/src/androidTest/java/dev/adriankuta/visualizer/ExampleInstrumentedTest.kt
@@ -0,0 +1,24 @@
+package dev.adriankuta.visualizer
+
+import androidx.test.platform.app.InstrumentationRegistry
+import androidx.test.ext.junit.runners.AndroidJUnit4
+
+import org.junit.Test
+import org.junit.runner.RunWith
+
+import org.junit.Assert.*
+
+/**
+ * Instrumented test, which will execute on an Android device.
+ *
+ * See [testing documentation](http://d.android.com/tools/testing).
+ */
+@RunWith(AndroidJUnit4::class)
+class ExampleInstrumentedTest {
+    @Test
+    fun useAppContext() {
+        // Context of the app under test.
+        val appContext = InstrumentationRegistry.getInstrumentation().targetContext
+        assertEquals("dev.adriankuta.visualizer", appContext.packageName)
+    }
+}
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -0,0 +1,30 @@
+<?xml version="1.0" encoding="utf-8"?>
+<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:allowBackup="true"
+        android:dataExtractionRules="@xml/data_extraction_rules"
+        android:fullBackupContent="@xml/backup_rules"
+        android:icon="@mipmap/ic_launcher"
+        android:label="@string/app_name"
+        android:roundIcon="@mipmap/ic_launcher_round"
+        android:supportsRtl="true"
+        android:theme="@style/Theme.Visualizer">
+        <activity
+            android:name=".MainActivity"
+            android:exported="true"
+            android:label="@string/app_name"
+            android:theme="@style/Theme.Visualizer">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+    </application>
+
+</manifest>
--- a/app/src/main/java/dev/adriankuta/visualizer/AudioSessionsTracker.kt
+++ b/app/src/main/java/dev/adriankuta/visualizer/AudioSessionsTracker.kt
@@ -0,0 +1,17 @@
+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() {}
+}
--- a/app/src/main/java/dev/adriankuta/visualizer/MainActivity.kt
+++ b/app/src/main/java/dev/adriankuta/visualizer/MainActivity.kt
@@ -0,0 +1,177 @@
+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 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.ui.theme.VisualizerTheme
+
+/**
+ * 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)
+        enableEdgeToEdge()
+        setContent {
+            VisualizerTheme {
+                Scaffold(modifier = Modifier.fillMaxSize()) { innerPadding ->
+                    VisualizerScreen(modifier = Modifier.padding(innerPadding))
+                }
+            }
+        }
+    }
+}
+
+/**
+ * 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_START -> runCatching { controller.start() }
+                Lifecycle.Event.ON_STOP -> 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()
+                .weight(1f)
+                .verticalScroll(rememberScrollState())
+        ) {
+            Text("Android Visualizer Demo", style = MaterialTheme.typography.headlineSmall)
+            Spacer(Modifier.height(8.dp))
+            if (!permissionGranted) {
+                dev.adriankuta.visualizer.components.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))
+
+            dev.adriankuta.visualizer.components.WaveformView(data = waveform)
+
+            Spacer(Modifier.height(8.dp))
+
+            dev.adriankuta.visualizer.components.FftBarsView(data = fft)
+
+            Spacer(Modifier.height(12.dp))
+            HorizontalDivider()
+            Spacer(Modifier.height(12.dp))
+
+            dev.adriankuta.visualizer.components.MetricsSection(
+                waveform = waveform,
+                fft = fft
+            )
+        }
+        dev.adriankuta.visualizer.components.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()
+    }
+}
--- a/app/src/main/java/dev/adriankuta/visualizer/VisualizerController.kt
+++ b/app/src/main/java/dev/adriankuta/visualizer/VisualizerController.kt
@@ -0,0 +1,90 @@
+package dev.adriankuta.visualizer
+
+import android.media.audiofx.Visualizer
+import android.os.Handler
+import android.os.Looper
+import android.os.SystemClock
+
+/**
+ * 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
+
+    // Ensure UI updates happen on the main thread and at a reasonable frame rate
+    private val mainHandler = Handler(Looper.getMainLooper())
+    private val minIntervalMs = 16L // ~60 FPS
+    @Volatile private var lastWaveformDispatch = 0L
+    @Volatile private var lastFftDispatch = 0L
+
+    /**
+     * 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 {
+            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() // allow max rate; we'll throttle ourselves
+            v.setDataCaptureListener(object : Visualizer.OnDataCaptureListener {
+                override fun onWaveFormDataCapture(
+                    visualizer: Visualizer?,
+                    waveform: ByteArray?,
+                    samplingRate: Int
+                ) {
+                    if (waveform == null) return
+                    val now = SystemClock.uptimeMillis()
+                    if (now - lastWaveformDispatch >= minIntervalMs) {
+                        lastWaveformDispatch = now
+                        val copy = waveform.copyOf()
+                        mainHandler.post { onWaveform(copy) }
+                    }
+                }
+
+                override fun onFftDataCapture(
+                    visualizer: Visualizer?,
+                    fft: ByteArray?,
+                    samplingRate: Int
+                ) {
+                    if (fft == null) return
+                    val now = SystemClock.uptimeMillis()
+                    if (now - lastFftDispatch >= minIntervalMs) {
+                        lastFftDispatch = now
+                        val copy = fft.copyOf()
+                        mainHandler.post { onFft(copy) }
+                    }
+                }
+            }, rate, true, true)
+            v.enabled = true
+            visualizer = v
+        } catch (e: Throwable) {
+            // If Visualizer cannot be initialized (e.g. permission or device restriction), ensure cleanup
+            stop()
+            throw e
+        }
+    }
+
+    /**
+     * Stops capturing audio data and releases the underlying [Visualizer].
+     * Safe to call multiple times.
+     */
+    @Synchronized
+    fun stop() {
+        visualizer?.enabled = false
+        visualizer?.release()
+        visualizer = null
+        lastWaveformDispatch = 0L
+        lastFftDispatch = 0L
+    }
+}
--- a/app/src/main/java/dev/adriankuta/visualizer/components/ControlButtons.kt
+++ b/app/src/main/java/dev/adriankuta/visualizer/components/ControlButtons.kt
@@ -0,0 +1,30 @@
+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") }
+    }
+}
--- a/app/src/main/java/dev/adriankuta/visualizer/components/FftBarsView.kt
+++ b/app/src/main/java/dev/adriankuta/visualizer/components/FftBarsView.kt
@@ -0,0 +1,99 @@
+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.runtime.LaunchedEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+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 with smoothing for natural transitions.
+ *
+ * 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)
+
+    var smoothed by remember { mutableStateOf<FloatArray?>(null) }
+
+    // Update smoothed magnitudes whenever new FFT data arrives
+    LaunchedEffect(data) {
+        val bytes = data ?: return@LaunchedEffect
+        if (bytes.size < 2) return@LaunchedEffect
+        val n = bytes.size / 2
+        val barCount = min(64, n)
+        val target = FloatArray(barCount) { i ->
+            val re = bytes[2 * i].toInt()
+            val im = bytes[2 * i + 1].toInt()
+            val mag = hypot(re.toDouble(), im.toDouble()).toFloat()
+            // Scale to 0..1 range (with a bit of headroom capped later in draw)
+            (mag / 128f).coerceIn(0f, 1.5f).coerceAtMost(1f)
+        }
+        val prev = smoothed
+        val rise = 0.35f
+        val decay = 0.12f
+        smoothed = if (prev == null || prev.size != target.size) {
+            target
+        } else {
+            val out = FloatArray(target.size)
+            for (i in target.indices) {
+                val a = if (target[i] > prev[i]) rise else decay
+                out[i] = prev[i] + (target[i] - prev[i]) * a
+            }
+            out
+        }
+    }
+
+    Canvas(
+        modifier = modifier
+            .fillMaxWidth()
+            .height(160.dp)
+            .padding(vertical = 4.dp)
+    ) {
+        val w = size.width
+        val h = size.height
+        val values = smoothed
+        if (values != null && values.isNotEmpty()) {
+            val barCount = values.size
+            val barWidth = w / barCount
+            for (i in 0 until barCount) {
+                val v = values[i].coerceIn(0f, 1f)
+                val barHeight = h * v
+                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
+            )
+        }
+    }
+}
--- a/app/src/main/java/dev/adriankuta/visualizer/components/MetricsSection.kt
+++ b/app/src/main/java/dev/adriankuta/visualizer/components/MetricsSection.kt
@@ -0,0 +1,74 @@
+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()
+}
--- a/app/src/main/java/dev/adriankuta/visualizer/components/PermissionSection.kt
+++ b/app/src/main/java/dev/adriankuta/visualizer/components/PermissionSection.kt
@@ -0,0 +1,33 @@
+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")
+    }
+}
--- a/app/src/main/java/dev/adriankuta/visualizer/components/WaveformView.kt
+++ b/app/src/main/java/dev/adriankuta/visualizer/components/WaveformView.kt
@@ -0,0 +1,89 @@
+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.runtime.LaunchedEffect
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.setValue
+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 with smoothing to reduce jitter.
+ *
+ * @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)
+
+    // Keep a smoothed copy of the latest waveform for softer transitions
+    var smoothed by remember { mutableStateOf<FloatArray?>(null) }
+
+    // Update smoothed values whenever new data arrives using exponential smoothing
+    LaunchedEffect(data) {
+        val bytes = data ?: return@LaunchedEffect
+        if (bytes.isEmpty()) return@LaunchedEffect
+        val target = FloatArray(bytes.size) { i -> ((bytes[i].toInt() and 0xFF) / 255f) }
+        val prev = smoothed
+        val alpha = 0.22f // smoothing factor; lower = smoother
+        smoothed = if (prev == null || prev.size != target.size) {
+            target
+        } else {
+            val out = FloatArray(target.size)
+            for (i in target.indices) {
+                out[i] = prev[i] + (target[i] - prev[i]) * alpha
+            }
+            out
+        }
+    }
+
+    Canvas(
+        modifier = modifier
+            .fillMaxWidth()
+            .height(120.dp)
+            .padding(vertical = 4.dp)
+    ) {
+        val w = size.width
+        val h = size.height
+        val values = smoothed
+        if (values == null || values.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 / (values.size - 1).coerceAtLeast(1)
+            for (i in values.indices) {
+                val x = i * stepX
+                val y = h * (1f - values[i])
+                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
+            )
+        }
+    }
+}
--- a/app/src/main/java/dev/adriankuta/visualizer/ui/theme/Color.kt
+++ b/app/src/main/java/dev/adriankuta/visualizer/ui/theme/Color.kt
@@ -0,0 +1,11 @@
+package dev.adriankuta.visualizer.ui.theme
+
+import androidx.compose.ui.graphics.Color
+
+val Purple80 = Color(0xFFD0BCFF)
+val PurpleGrey80 = Color(0xFFCCC2DC)
+val Pink80 = Color(0xFFEFB8C8)
+
+val Purple40 = Color(0xFF6650a4)
+val PurpleGrey40 = Color(0xFF625b71)
+val Pink40 = Color(0xFF7D5260)
--- a/app/src/main/java/dev/adriankuta/visualizer/ui/theme/Theme.kt
+++ b/app/src/main/java/dev/adriankuta/visualizer/ui/theme/Theme.kt
@@ -0,0 +1,58 @@
+package dev.adriankuta.visualizer.ui.theme
+
+import android.app.Activity
+import android.os.Build
+import androidx.compose.foundation.isSystemInDarkTheme
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.darkColorScheme
+import androidx.compose.material3.dynamicDarkColorScheme
+import androidx.compose.material3.dynamicLightColorScheme
+import androidx.compose.material3.lightColorScheme
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.platform.LocalContext
+
+private val DarkColorScheme = darkColorScheme(
+    primary = Purple80,
+    secondary = PurpleGrey80,
+    tertiary = Pink80
+)
+
+private val LightColorScheme = lightColorScheme(
+    primary = Purple40,
+    secondary = PurpleGrey40,
+    tertiary = Pink40
+
+    /* Other default colors to override
+    background = Color(0xFFFFFBFE),
+    surface = Color(0xFFFFFBFE),
+    onPrimary = Color.White,
+    onSecondary = Color.White,
+    onTertiary = Color.White,
+    onBackground = Color(0xFF1C1B1F),
+    onSurface = Color(0xFF1C1B1F),
+    */
+)
+
+@Composable
+fun VisualizerTheme(
+    darkTheme: Boolean = isSystemInDarkTheme(),
+    // Dynamic color is available on Android 12+
+    dynamicColor: Boolean = true,
+    content: @Composable () -> Unit
+) {
+    val colorScheme = when {
+        dynamicColor && Build.VERSION.SDK_INT >= Build.VERSION_CODES.S -> {
+            val context = LocalContext.current
+            if (darkTheme) dynamicDarkColorScheme(context) else dynamicLightColorScheme(context)
+        }
+
+        darkTheme -> DarkColorScheme
+        else -> LightColorScheme
+    }
+
+    MaterialTheme(
+        colorScheme = colorScheme,
+        typography = Typography,
+        content = content
+    )
+}
--- a/app/src/main/java/dev/adriankuta/visualizer/ui/theme/Type.kt
+++ b/app/src/main/java/dev/adriankuta/visualizer/ui/theme/Type.kt
@@ -0,0 +1,34 @@
+package dev.adriankuta.visualizer.ui.theme
+
+import androidx.compose.material3.Typography
+import androidx.compose.ui.text.TextStyle
+import androidx.compose.ui.text.font.FontFamily
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.unit.sp
+
+// Set of Material typography styles to start with
+val Typography = Typography(
+    bodyLarge = TextStyle(
+        fontFamily = FontFamily.Default,
+        fontWeight = FontWeight.Normal,
+        fontSize = 16.sp,
+        lineHeight = 24.sp,
+        letterSpacing = 0.5.sp
+    )
+    /* Other default text styles to override
+    titleLarge = TextStyle(
+        fontFamily = FontFamily.Default,
+        fontWeight = FontWeight.Normal,
+        fontSize = 22.sp,
+        lineHeight = 28.sp,
+        letterSpacing = 0.sp
+    ),
+    labelSmall = TextStyle(
+        fontFamily = FontFamily.Default,
+        fontWeight = FontWeight.Medium,
+        fontSize = 11.sp,
+        lineHeight = 16.sp,
+        letterSpacing = 0.5.sp
+    )
+    */
+)
--- a/app/src/main/res/drawable/ic_launcher_background.xml
+++ b/app/src/main/res/drawable/ic_launcher_background.xml
@@ -0,0 +1,170 @@
+<?xml version="1.0" encoding="utf-8"?>
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="108dp"
+    android:height="108dp"
+    android:viewportWidth="108"
+    android:viewportHeight="108">
+    <path
+        android:fillColor="#3DDC84"
+        android:pathData="M0,0h108v108h-108z" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M9,0L9,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,0L19,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M29,0L29,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M39,0L39,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M49,0L49,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M59,0L59,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M69,0L69,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M79,0L79,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M89,0L89,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M99,0L99,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,9L108,9"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,19L108,19"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,29L108,29"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,39L108,39"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,49L108,49"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,59L108,59"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,69L108,69"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,79L108,79"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,89L108,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,99L108,99"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,29L89,29"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,39L89,39"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,49L89,49"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,59L89,59"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,69L89,69"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,79L89,79"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M29,19L29,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M39,19L39,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M49,19L49,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M59,19L59,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M69,19L69,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M79,19L79,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+</vector>
--- a/app/src/main/res/drawable/ic_launcher_foreground.xml
+++ b/app/src/main/res/drawable/ic_launcher_foreground.xml
@@ -0,0 +1,30 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:aapt="http://schemas.android.com/aapt"
+    android:width="108dp"
+    android:height="108dp"
+    android:viewportWidth="108"
+    android:viewportHeight="108">
+    <path android:pathData="M31,63.928c0,0 6.4,-11 12.1,-13.1c7.2,-2.6 26,-1.4 26,-1.4l38.1,38.1L107,108.928l-32,-1L31,63.928z">
+        <aapt:attr name="android:fillColor">
+            <gradient
+                android:endX="85.84757"
+                android:endY="92.4963"
+                android:startX="42.9492"
+                android:startY="49.59793"
+                android:type="linear">
+                <item
+                    android:color="#44000000"
+                    android:offset="0.0" />
+                <item
+                    android:color="#00000000"
+                    android:offset="1.0" />
+            </gradient>
+        </aapt:attr>
+    </path>
+    <path
+        android:fillColor="#FFFFFF"
+        android:fillType="nonZero"
+        android:pathData="M65.3,45.828l3.8,-6.6c0.2,-0.4 0.1,-0.9 -0.3,-1.1c-0.4,-0.2 -0.9,-0.1 -1.1,0.3l-3.9,6.7c-6.3,-2.8 -13.4,-2.8 -19.7,0l-3.9,-6.7c-0.2,-0.4 -0.7,-0.5 -1.1,-0.3C38.8,38.328 38.7,38.828 38.9,39.228l3.8,6.6C36.2,49.428 31.7,56.028 31,63.928h46C76.3,56.028 71.8,49.428 65.3,45.828zM43.4,57.328c-0.8,0 -1.5,-0.5 -1.8,-1.2c-0.3,-0.7 -0.1,-1.5 0.4,-2.1c0.5,-0.5 1.4,-0.7 2.1,-0.4c0.7,0.3 1.2,1 1.2,1.8C45.3,56.528 44.5,57.328 43.4,57.328L43.4,57.328zM64.6,57.328c-0.8,0 -1.5,-0.5 -1.8,-1.2s-0.1,-1.5 0.4,-2.1c0.5,-0.5 1.4,-0.7 2.1,-0.4c0.7,0.3 1.2,1 1.2,1.8C66.5,56.528 65.6,57.328 64.6,57.328L64.6,57.328z"
+        android:strokeWidth="1"
+        android:strokeColor="#00000000" />
+</vector>
--- a/app/src/main/res/mipmap-anydpi-v26/ic_launcher.xml
+++ b/app/src/main/res/mipmap-anydpi-v26/ic_launcher.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@drawable/ic_launcher_background" />
+    <foreground android:drawable="@drawable/ic_launcher_foreground" />
+    <monochrome android:drawable="@drawable/ic_launcher_foreground" />
+</adaptive-icon>
--- a/app/src/main/res/mipmap-anydpi-v26/ic_launcher_round.xml
+++ b/app/src/main/res/mipmap-anydpi-v26/ic_launcher_round.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@drawable/ic_launcher_background" />
+    <foreground android:drawable="@drawable/ic_launcher_foreground" />
+    <monochrome android:drawable="@drawable/ic_launcher_foreground" />
+</adaptive-icon>
--- a/app/src/main/res/mipmap-hdpi/ic_launcher.webp
+++ b/app/src/main/res/mipmap-hdpi/ic_launcher.webp
--- a/app/src/main/res/mipmap-hdpi/ic_launcher_round.webp
+++ b/app/src/main/res/mipmap-hdpi/ic_launcher_round.webp
--- a/app/src/main/res/mipmap-mdpi/ic_launcher.webp
+++ b/app/src/main/res/mipmap-mdpi/ic_launcher.webp
--- a/app/src/main/res/mipmap-mdpi/ic_launcher_round.webp
+++ b/app/src/main/res/mipmap-mdpi/ic_launcher_round.webp
--- a/app/src/main/res/mipmap-xhdpi/ic_launcher.webp
+++ b/app/src/main/res/mipmap-xhdpi/ic_launcher.webp
--- a/app/src/main/res/mipmap-xhdpi/ic_launcher_round.webp
+++ b/app/src/main/res/mipmap-xhdpi/ic_launcher_round.webp
--- a/app/src/main/res/mipmap-xxhdpi/ic_launcher.webp
+++ b/app/src/main/res/mipmap-xxhdpi/ic_launcher.webp
--- a/app/src/main/res/mipmap-xxhdpi/ic_launcher_round.webp
+++ b/app/src/main/res/mipmap-xxhdpi/ic_launcher_round.webp
--- a/app/src/main/res/mipmap-xxxhdpi/ic_launcher.webp
+++ b/app/src/main/res/mipmap-xxxhdpi/ic_launcher.webp
--- a/app/src/main/res/mipmap-xxxhdpi/ic_launcher_round.webp
+++ b/app/src/main/res/mipmap-xxxhdpi/ic_launcher_round.webp
--- a/app/src/main/res/values/colors.xml
+++ b/app/src/main/res/values/colors.xml
@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <color name="purple_200">#FFBB86FC</color>
+    <color name="purple_500">#FF6200EE</color>
+    <color name="purple_700">#FF3700B3</color>
+    <color name="teal_200">#FF03DAC5</color>
+    <color name="teal_700">#FF018786</color>
+    <color name="black">#FF000000</color>
+    <color name="white">#FFFFFFFF</color>
+</resources>
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -0,0 +1,3 @@
+<resources>
+    <string name="app_name">Visualizer</string>
+</resources>
--- a/app/src/main/res/values/themes.xml
+++ b/app/src/main/res/values/themes.xml
@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+
+    <style name="Theme.Visualizer" parent="android:Theme.Material.Light.NoActionBar" />
+</resources>
--- a/app/src/main/res/xml/backup_rules.xml
+++ b/app/src/main/res/xml/backup_rules.xml
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+   Sample backup rules file; uncomment and customize as necessary.
+   See https://developer.android.com/guide/topics/data/autobackup
+   for details.
+   Note: This file is ignored for devices older than API 31
+   See https://developer.android.com/about/versions/12/backup-restore
+-->
+<full-backup-content>
+    <!--
+   <include domain="sharedpref" path="."/>
+   <exclude domain="sharedpref" path="device.xml"/>
+-->
+</full-backup-content>
--- a/app/src/main/res/xml/data_extraction_rules.xml
+++ b/app/src/main/res/xml/data_extraction_rules.xml
@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+   Sample data extraction rules file; uncomment and customize as necessary.
+   See https://developer.android.com/about/versions/12/backup-restore#xml-changes
+   for details.
+-->
+<data-extraction-rules>
+    <cloud-backup>
+        <!-- TODO: Use <include> and <exclude> to control what is backed up.
+        <include .../>
+        <exclude .../>
+        -->
+    </cloud-backup>
+    <!--
+    <device-transfer>
+        <include .../>
+        <exclude .../>
+    </device-transfer>
+    -->
+</data-extraction-rules>
--- a/app/src/test/java/dev/adriankuta/visualizer/ExampleUnitTest.kt
+++ b/app/src/test/java/dev/adriankuta/visualizer/ExampleUnitTest.kt
@@ -0,0 +1,17 @@
+package dev.adriankuta.visualizer
+
+import org.junit.Test
+
+import org.junit.Assert.*
+
+/**
+ * Example local unit test, which will execute on the development machine (host).
+ *
+ * See [testing documentation](http://d.android.com/tools/testing).
+ */
+class ExampleUnitTest {
+    @Test
+    fun addition_isCorrect() {
+        assertEquals(4, 2 + 2)
+    }
+}