performance improvements + oscilloscope

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

@@ -24,5 +24,10 @@ class AstraScopeModule : Module() {
     Function("getSpectrumFrame") { out: Float32Array ->
       ScopeBridge.nativeFillSpectrum(out.toDirectBuffer(), out.length)
     }
+
+    // Fill `out` with render-ready oscilloscope points (~[-1,1]).
+    Function("getOscilloscopeFrame") { out: Float32Array ->
+      ScopeBridge.nativeFillOscilloscope(out.toDirectBuffer(), out.length)
+    }
   }
 }

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

@@ -33,4 +33,12 @@ object ScopeBridge {
    * Returns the number of bins written. Zero-copy: writes straight into JS memory.
    */
   external fun nativeFillSpectrum(buffer: java.nio.ByteBuffer, capacityFloats: Int): Int
+
+  /**
+   * Render thread. Fill `buffer` (a direct ByteBuffer over the JS Float32Array's
+   * memory) with render-ready, evenly spaced points from the latest triggered
+   * oscilloscope window. Returns the number of points written. Zero-copy:
+   * writes straight into JS memory.
+   */
+  external fun nativeFillOscilloscope(buffer: java.nio.ByteBuffer, capacityFloats: Int): Int
 }