feat(ui): add spectrum analyzer visualizer

app/src/main/cpp/extra.cpp

@@ -0,0 +1,70 @@
+#include <jni.h>
+#include <android/native_window_jni.h>
+#include <android/native_window.h>
+#include <android/log.h>
+#include <vector>
+#include <algorithm>
+
+
+extern "C" {
+
+JNIEXPORT void JNICALL
+Java_com_michatec_radio_helpers_ExtrasHelper_visualize(JNIEnv *env, jclass clazz, jobject surface, jfloatArray data) {
+    if (!surface) return;
+    ANativeWindow* window = ANativeWindow_fromSurface(env, surface);
+    if (!window) return;
+
+    jsize len = env->GetArrayLength(data);
+    if (len == 0) {
+        ANativeWindow_release(window);
+        return;
+    }
+    jfloat* body = env->GetFloatArrayElements(data, nullptr);
+
+    ANativeWindow_Buffer buffer;
+    ANativeWindow_setBuffersGeometry(window, 0, 0, WINDOW_FORMAT_RGBA_8888);
+
+    if (ANativeWindow_lock(window, &buffer, nullptr) == 0) {
+        auto* pixels = static_cast<uint32_t*>(buffer.bits);
+
+        // Clear background (Dark Grey)
+        for (int y = 0; y < buffer.height; y++) {
+            for (int x = 0; x < buffer.width; x++) {
+                pixels[y * buffer.stride + x] = 0xFF121212;
+            }
+        }
+
+        // Draw bars
+        int displayBins = std::min(static_cast<int>(len), 128);
+        float barWidth = static_cast<float>(buffer.width) / static_cast<float>(displayBins);
+
+        for (int i = 0; i < displayBins; i++) {
+            // Keep original order: bass (low freq) at left, treble (high freq) at right
+            float val = body[i];
+            float scaledVal = val * 5.0f;
+            int barHeight = static_cast<int>(scaledVal * static_cast<float>(buffer.height));
+
+            if (barHeight > buffer.height) barHeight = buffer.height;
+            if (barHeight < 12) barHeight = 12; // Min height
+
+            int startX = static_cast<int>(static_cast<float>(i) * barWidth);
+            int endX = static_cast<int>(static_cast<float>(i + 1) * barWidth);
+            int barBottom = buffer.height;
+            int barTop = barBottom - barHeight;
+
+            for (int x = startX; x <= endX; x++) {
+                if (x < 0 || x >= buffer.width) continue;
+                for (int y = barTop; y < barBottom; y++) {
+                    pixels[y * buffer.stride + x] = 0xFFC5DA03;
+                }
+            }
+        }
+
+        ANativeWindow_unlockAndPost(window);
+    }
+
+    env->ReleaseFloatArrayElements(data, body, JNI_ABORT);
+    ANativeWindow_release(window);
+}
+
+} // extern "C"