m3, ui/ux, and more

modules/astra-scope/android/src/main/AndroidManifest.xml

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+<manifest>
+</manifest>

modules/astra-scope/android/src/main/java/expo/modules/astrascope/AstraScopeModule.kt

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+package expo.modules.astrascope
+
+import expo.modules.kotlin.modules.Module
+import expo.modules.kotlin.modules.ModuleDefinition
+import expo.modules.kotlin.typedarray.Float32Array
+
+/**
+ * JS surface for the realtime scope. Both functions are synchronous (JSI):
+ * [getSpectrumFrame] is pulled once per render frame from the JS thread and
+ * fills a JS-preallocated Float32Array in place (no per-frame allocation, no
+ * event-emitter traffic). The PCM that feeds it arrives on the audio thread via
+ * the vendored kotlin-audio tap -> [ScopeBridge].
+ */
+class AstraScopeModule : Module() {
+  override fun definition() = ModuleDefinition {
+    Name("AstraScope")
+
+    // Gate the audio-thread tap (off when backgrounded/paused/reduced-motion).
+    Function("setActive") { active: Boolean ->
+      ScopeBridge.active = active
+    }
+
+    // Fill `out` with the latest dB spectrum; returns the number of bins written.
+    Function("getSpectrumFrame") { out: Float32Array ->
+      ScopeBridge.nativeFillSpectrum(out.toDirectBuffer(), out.length)
+    }
+  }
+}

modules/astra-scope/android/src/main/java/expo/modules/astrascope/ScopeBridge.kt

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+package expo.modules.astrascope
+
+/**
+ * Process-wide bridge to the native scope driver (libastrascope.so).
+ *
+ * Loaded once here; the vendored kotlin-audio PCM tap (ScopeTapAudioProcessor)
+ * calls [nativePushFrames]/[nativeConfigure] from the ExoPlayer audio thread,
+ * while [AstraScopeModule] calls [nativeFillSpectrum] from the JS thread. The
+ * native side is single-producer/single-consumer and lock-free on the audio
+ * path; see scope_ring.h.
+ *
+ * [active] gates the tap so a backgrounded/paused app pays ~zero in the audio
+ * callback. The lifecycle owner (RN side) flips it via AstraScope.setActive().
+ */
+object ScopeBridge {
+  init {
+    System.loadLibrary("astrascope")
+  }
+
+  /** Set by the lifecycle owner; checked cheaply in the audio callback. */
+  @Volatile
+  var active: Boolean = false
+
+  /** Audio thread. Tell the analyzer the stream's sample rate / channels. */
+  external fun nativeConfigure(sampleRate: Int, channelCount: Int)
+
+  /** Audio thread. Push interleaved float PCM (frameCount * channelCount). */
+  external fun nativePushFrames(frames: FloatArray, frameCount: Int, channelCount: Int)
+
+  /**
+   * Render thread. Fill `buffer` (a direct ByteBuffer over the JS Float32Array's
+   * memory) with the latest dB spectrum, up to `capacityFloats` floats.
+   * Returns the number of bins written. Zero-copy: writes straight into JS memory.
+   */
+  external fun nativeFillSpectrum(buffer: java.nio.ByteBuffer, capacityFloats: Int): Int
+}