Add Spectrogram example

Author: stnkl

examples/Spectrogram/Animations/Spectrogram.h

@@ -0,0 +1,42 @@
+#pragma once
+
+// This example requires the use of https://github.com/stnkl/FastLEDHub_AudioViz to send
+// spectrum data to the ESP32/ESP8266 running FastLEDHub.
+
+#include <FastLEDHub.h>
+
+#include <math.h>
+
+extern CRGB leds[];
+
+class Spectrogram : public Animation
+{
+public:
+  using Animation::Animation;
+
+  uint8_t interpolateSpectrum(uint16_t led)
+  {
+    float stepSize = (float)(SPECTRUM_LENGTH - 1) / ((float)FastLEDHub.size() - 1);
+    float spectrumPosition = led * stepSize;
+    int16_t spectrumFloorIndex = (int16_t)spectrumPosition % SPECTRUM_LENGTH;
+    int16_t spectrumFloor = FastLEDHub.spectrumData[spectrumFloorIndex];
+    int16_t spectrumCeil = FastLEDHub.spectrumData[(spectrumFloorIndex + 1) % SPECTRUM_LENGTH];
+    uint8_t intensity = spectrumFloor + fmod(spectrumPosition, 1) * (spectrumCeil - spectrumFloor);
+    return intensity;
+  }
+
+  void reset()
+  {
+  }
+
+  void loop()
+  {
+    for (uint16_t i = 0; i < FastLEDHub.size(); i++)
+    {
+      CRGB color = CRGB::White;
+      leds[i] = color.nscale8(interpolateSpectrum(i));
+    }
+
+    FastLEDHub.show();
+  }
+};

examples/Spectrogram/Spectrogram.ino

@@ -0,0 +1,22 @@
+#include <FastLEDHub.h>
+
+#include "Animations/Spectrogram.h"
+
+#define NUM_LEDS 100
+#define LIGHTSTRIP_PIN 5
+#define LED_TYPE WS2812B
+
+CRGB leds[NUM_LEDS];
+
+void setup()
+{
+  FastLEDHub.initialize("Spectrogram Example");
+  FastLEDHub.addLeds<LED_TYPE, LIGHTSTRIP_PIN, GRB>(leds, NUM_LEDS);
+
+  FastLEDHub.registerAnimation(new Spectrogram("Spectrogram"));
+}
+
+void loop()
+{
+  FastLEDHub.handle();
+}