Add A Progress Slider to PowerPlay (#2345)

madebymozart · web-flow · commit f0207e78f127 · 2026-03-04T11:38:51.000-05:00
* Add playback seeking and progress tracking.

* PowerPlay: Hide slider when in PCM Offload mode

* Remove flush when offloaded.
diff --git a/samples/iolib/src/main/cpp/player/SampleSource.h b/samples/iolib/src/main/cpp/player/SampleSource.h
@@ -63,6 +63,14 @@ class SampleSource: public DataSource {
 
     int32_t getPlayHeadPosition() const { return mCurSampleIndex; }
 
+    void setPlayHeadPosition(int32_t position) {
+        if (mSampleBuffer != nullptr && position >= 0 && position < mSampleBuffer->getNumSamples()) {
+            mCurSampleIndex = position;
+        }
+    }
+
+    SampleBuffer* getSampleBuffer() { return mSampleBuffer; }
+
     void setPan(float pan) {
         if (pan < PAN_HARDLEFT) {
             mPan = PAN_HARDLEFT;
diff --git a/samples/powerplay/src/main/cpp/PowerPlayJNI.cpp b/samples/powerplay/src/main/cpp/PowerPlayJNI.cpp
@@ -327,6 +327,38 @@ Java_com_google_oboe_samples_powerplay_engine_PowerPlayAudioPlayer_getCurrentlyP
     return player.getCurrentlyPlayingIndex();
 }
 
+/**
+ * Native (JNI) implementation of PowerPlayAudioPlayer.getPlaybackPositionMillisNative()
+ */
+JNIEXPORT jlong JNICALL
+Java_com_google_oboe_samples_powerplay_engine_PowerPlayAudioPlayer_getPlaybackPositionMillisNative(
+        JNIEnv *env,
+        jobject) {
+    return (jlong) player.getPlaybackPositionMillis();
+}
+
+/**
+ * Native (JNI) implementation of PowerPlayAudioPlayer.seekToNative()
+ */
+JNIEXPORT void JNICALL
+Java_com_google_oboe_samples_powerplay_engine_PowerPlayAudioPlayer_seekToNative(
+        JNIEnv *env,
+        jobject,
+        jint positionMillis) {
+    player.seekTo(positionMillis);
+}
+
+/**
+ * Native (JNI) implementation of PowerPlayAudioPlayer.getDurationMillisNative()
+ */
+JNIEXPORT jlong JNICALL
+Java_com_google_oboe_samples_powerplay_engine_PowerPlayAudioPlayer_getDurationMillisNative(
+        JNIEnv *env,
+        jobject,
+        jint index) {
+    return (jlong) player.getDurationMillis(index);
+}
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/samples/powerplay/src/main/cpp/PowerPlayMultiPlayer.cpp b/samples/powerplay/src/main/cpp/PowerPlayMultiPlayer.cpp
@@ -242,3 +242,81 @@ bool PowerPlayMultiPlayer::isOffloaded() {
 
   return mAudioStream->getPerformanceMode() == PerformanceMode::PowerSavingOffloaded;
 }
+
+int64_t PowerPlayMultiPlayer::getPlaybackPositionMillis() {
+    if (mAudioStream == nullptr) return 0;
+
+    int32_t index = getCurrentlyPlayingIndex();
+    if (index == -1) return 0;
+
+    auto* sampleSource = mSampleSources[index];
+    auto* sampleBuffer = sampleSource->getSampleBuffer();
+    if (!sampleBuffer) return 0;
+    int32_t sampleChannels = sampleBuffer->getProperties().channelCount;
+
+    int64_t framePosition = 0;
+    int64_t timeNanoseconds = 0;
+    auto result = mAudioStream->getTimestamp(CLOCK_MONOTONIC, &framePosition, &timeNanoseconds);
+
+    int32_t sampleRate = mAudioStream->getSampleRate();
+    if (sampleRate <= 0) return 0;
+
+    int64_t readFrames = sampleSource->getPlayHeadPosition() / sampleChannels;
+    int64_t presentedFrame = 0;
+
+    if (result == Result::OK) {
+        // Calculate the latency: how many frames are between the callback and the speakers.
+        int64_t framesWritten = mAudioStream->getFramesWritten();
+        int64_t latencyFrames = framesWritten - framePosition;
+        if (latencyFrames < 0) latencyFrames = 0;
+
+        presentedFrame = readFrames - latencyFrames;
+    } else {
+        // Fallback to callback position if timestamp is not available.
+        presentedFrame = readFrames;
+    }
+
+    if (presentedFrame < 0) presentedFrame = 0;
+
+    return (presentedFrame * 1000) / sampleRate;
+}
+
+void PowerPlayMultiPlayer::seekTo(int32_t positionMillis) {
+    if (mAudioStream == nullptr) return;
+
+    int32_t index = getCurrentlyPlayingIndex();
+    if (index == -1) return;
+
+    int32_t sampleRate = mAudioStream->getSampleRate();
+    if (sampleRate <= 0) return;
+
+    auto* sampleSource = mSampleSources[index];
+    auto* sampleBuffer = sampleSource->getSampleBuffer();
+    if (!sampleBuffer) return;
+    int32_t sampleChannels = sampleBuffer->getProperties().channelCount;
+
+    int64_t targetFrame = (static_cast<int64_t>(positionMillis) * sampleRate) / 1000;
+
+    // Boundary check for the current sample.
+    if (sampleBuffer) {
+        if (targetFrame < 0) targetFrame = 0;
+        int64_t totalFrames = sampleBuffer->getNumSamples() / sampleChannels;
+        if (targetFrame >= totalFrames) {
+            targetFrame = totalFrames - 1;
+        }
+    }
+
+    sampleSource->setPlayHeadPosition(static_cast<int32_t>(targetFrame * sampleChannels));
+}
+
+int64_t PowerPlayMultiPlayer::getDurationMillis(int32_t index) {
+    if (index < 0 || index >= mSampleSources.size()) return 0;
+    auto* sampleBuffer = mSampleSources[index]->getSampleBuffer();
+    if (!sampleBuffer) return 0;
+
+    int32_t channelCount = sampleBuffer->getProperties().channelCount;
+    int32_t sampleRate = mSampleRate;
+    if (sampleRate <= 0 || channelCount <= 0) return 0;
+
+    return (static_cast<int64_t>(sampleBuffer->getNumSamples() / channelCount) * 1000) / sampleRate;
+}
diff --git a/samples/powerplay/src/main/cpp/PowerPlayMultiPlayer.h b/samples/powerplay/src/main/cpp/PowerPlayMultiPlayer.h
@@ -52,6 +52,12 @@ class PowerPlayMultiPlayer : public iolib::SimpleMultiPlayer {
 
     bool isOffloaded();
 
+    int64_t getPlaybackPositionMillis();
+
+    void seekTo(int32_t positionMillis);
+
+    int64_t getDurationMillis(int32_t index);
+
 private:
     class MyPresentationCallback : public oboe::AudioStreamPresentationCallback {
     public:
diff --git a/samples/powerplay/src/main/kotlin/com/google/oboe/samples/powerplay/MainActivity.kt b/samples/powerplay/src/main/kotlin/com/google/oboe/samples/powerplay/MainActivity.kt
@@ -91,6 +91,7 @@ import androidx.compose.runtime.getValue
 import androidx.compose.runtime.livedata.observeAsState
 import androidx.compose.runtime.mutableFloatStateOf
 import androidx.compose.runtime.mutableIntStateOf
+import androidx.compose.runtime.mutableLongStateOf
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
@@ -129,6 +130,7 @@ import android.os.Looper
 import android.util.Log
 import com.google.oboe.samples.powerplay.automation.IntentBasedTestSupport
 import com.google.oboe.samples.powerplay.automation.IntentBasedTestSupport.LOG_TAG
+import kotlinx.coroutines.delay
 
 class MainActivity : ComponentActivity() {
 
@@ -402,11 +404,33 @@ class MainActivity : ComponentActivity() {
 
         var showInfoDialog by remember { mutableStateOf(false) }
 
+        // Real-time progress slider state
+        var assetsReady by remember { mutableStateOf(false) }
+        var playbackPosition by remember { mutableLongStateOf(0L) }
+        var isSeeking by remember { mutableStateOf(false) }
+        val duration = remember(playingSongIndex.intValue, assetsReady) { player.getDurationMillis(playingSongIndex.intValue) }
+
+        // Polling loop for slider position (~60fps)
+        LaunchedEffect(isPlaying, offload.intValue) {
+            if (isPlaying && offload.intValue != 3) {
+                while (true) {
+                    if (!isSeeking) {
+                        playbackPosition = player.getPlaybackPositionMillis()
+                    }
+                    delay(16)
+                }
+            } else {
+                playbackPosition = player.getPlaybackPositionMillis()
+            }
+        }
+
         // Sync pager with song index when automation changes it
         LaunchedEffect(playingSongIndex.intValue) {
             if (pagerState.currentPage != playingSongIndex.intValue) {
                 pagerState.animateScrollToPage(playingSongIndex.intValue)
             }
+            // Update playback position when song changes
+            playbackPosition = player.getPlaybackPositionMillis()
         }
 
         LaunchedEffect(pagerState) {
@@ -434,6 +458,7 @@ class MainActivity : ComponentActivity() {
             }
             // Assets are now loaded, process any pending automation intent
             assetsLoaded = true
+            assetsReady = true
             pendingAutomationIntent?.let {
                 processIntent(it)
                 pendingAutomationIntent = null
@@ -513,7 +538,51 @@ class MainActivity : ComponentActivity() {
                         VinylAlbumCoverAnimation(isSongPlaying = false, painter = painter)
                     }
                 }
+                
                 Spacer(modifier = Modifier.height(24.dp))
+
+                // Progress Slider
+                AnimatedVisibility(visible = offload.intValue != 3) {
+                    Column(
+                        modifier = Modifier
+                            .fillMaxWidth()
+                            .padding(horizontal = 32.dp)
+                    ) {
+                        Slider(
+                            value = if (duration > 0) playbackPosition.toFloat() / duration else 0f,
+                            onValueChange = { newValue ->
+                                isSeeking = true
+                                playbackPosition = (newValue * duration).toLong()
+                            },
+                            onValueChangeFinished = {
+                                player.seekTo(playbackPosition.toInt())
+                                isSeeking = false
+                            },
+                            colors = SliderDefaults.colors(
+                                thumbColor = MaterialTheme.colorScheme.primary,
+                                activeTrackColor = MaterialTheme.colorScheme.primary
+                            )
+                        )
+                        Row(
+                            modifier = Modifier.fillMaxWidth(),
+                            horizontalArrangement = Arrangement.SpaceBetween
+                        ) {
+                            Text(
+                                text = playbackPosition.convertToText(),
+                                fontSize = 12.sp,
+                                color = Color.Gray
+                            )
+                            Text(
+                                text = duration.convertToText(),
+                                fontSize = 12.sp,
+                                color = Color.Gray
+                            )
+                        }
+                    }
+                }
+
+                Spacer(modifier = Modifier.height(16.dp))
+
                 Row(
                     horizontalArrangement = Arrangement.SpaceEvenly,
                     verticalAlignment = Alignment.CenterVertically
diff --git a/samples/powerplay/src/main/kotlin/com/google/oboe/samples/powerplay/engine/PowerPlayAudioPlayer.kt b/samples/powerplay/src/main/kotlin/com/google/oboe/samples/powerplay/engine/PowerPlayAudioPlayer.kt
@@ -130,6 +130,21 @@ class PowerPlayAudioPlayer() : DefaultLifecycleObserver {
      */
     fun getCurrentlyPlayingIndex(): Int = getCurrentlyPlayingIndexNative()
 
+    /**
+     * Gets the current playback position in milliseconds.
+     */
+    fun getPlaybackPositionMillis(): Long = getPlaybackPositionMillisNative()
+
+    /**
+     * Seeks to a specific position in milliseconds.
+     */
+    fun seekTo(positionMillis: Int) = seekToNative(positionMillis)
+
+    /**
+     * Gets the duration of the track at the specified index in milliseconds.
+     */
+    fun getDurationMillis(index: Int): Long = getDurationMillisNative(index)
+
     /**
      * Native functions.
      * Load the library containing the native code including the JNI functions.
@@ -157,6 +172,9 @@ class PowerPlayAudioPlayer() : DefaultLifecycleObserver {
     private external fun setVolumeNative(volume: Float)
     private external fun isOffloadedNative(): Boolean
     private external fun getCurrentlyPlayingIndexNative(): Int
+    private external fun getPlaybackPositionMillisNative(): Long
+    private external fun seekToNative(positionMillis: Int)
+    private external fun getDurationMillisNative(index: Int): Long
 
     /**
      * Companion
