Merge pull request #301 from adafruit/pb-swirl

Add rainbow() fill function for easy color swirl

Adafruit_NeoPixel.cpp

@@ -3370,3 +3370,31 @@ uint32_t Adafruit_NeoPixel::gamma32(uint32_t x) {
     y[i] = gamma8(y[i]);
   return x; // Packed 32-bit return
 }
+
+/*!
+  @brief   Fill NeoPixel strip with one or more cycles of hues.
+           Everyone loves the rainbow swirl so much, now it's canon!
+  @param   first_hue   Hue of first pixel, 0-65535, representing one full
+                       cycle of the color wheel. Each subsequent pixel will
+                       be offset to complete one or more cycles over the
+                       length of the strip.
+  @param   reps        Number of cycles of the color wheel over the length
+                       of the strip. Default is 1. Negative values can be
+                       used to reverse the hue order.
+  @param   saturation  Saturation (optional), 0-255 = gray to pure hue,
+                       default = 255.
+  @param   brightness  Brightness/value (optional), 0-255 = off to max,
+                       default = 255. This is distinct and in combination
+                       with any configured global strip brightness.
+  @param   gammify     If true (default), apply gamma correction to colors
+                       for better appearance.
+*/
+void Adafruit_NeoPixel::rainbow(uint16_t first_hue, int8_t reps,
+  uint8_t saturation, uint8_t brightness, bool gammify) {
+  for (uint16_t i=0; i<numLEDs; i++) {
+    uint16_t hue = first_hue + (i * reps * 65536) / numLEDs;
+    uint32_t color = ColorHSV(hue, saturation, brightness);
+    if (gammify) color = gamma32(color);
+    setPixelColor(i, color);
+  }
+}

Adafruit_NeoPixel.h

@@ -360,6 +360,10 @@ class Adafruit_NeoPixel {
   */
   static uint32_t gamma32(uint32_t x);
 
+  void rainbow(uint16_t first_hue = 0, int8_t reps = 1,
+               uint8_t saturation = 255, uint8_t brightness = 255,
+               boolean gammify = true);
+
 protected:
 #ifdef NEO_KHZ400 // If 400 KHz NeoPixel support enabled...
   bool is800KHz; ///< true if 800 KHz pixels

examples/strandtest/strandtest.ino

@@ -105,20 +105,16 @@ void rainbow(int wait) {
   // Hue of first pixel runs 5 complete loops through the color wheel.
   // Color wheel has a range of 65536 but it's OK if we roll over, so
   // just count from 0 to 5*65536. Adding 256 to firstPixelHue each time
-  // means we'll make 5*65536/256 = 1280 passes through this outer loop:
+  // means we'll make 5*65536/256 = 1280 passes through this loop:
   for(long firstPixelHue = 0; firstPixelHue < 5*65536; firstPixelHue += 256) {
-    for(int i=0; i<strip.numPixels(); i++) { // For each pixel in strip...
-      // Offset pixel hue by an amount to make one full revolution of the
-      // color wheel (range of 65536) along the length of the strip
-      // (strip.numPixels() steps):
-      int pixelHue = firstPixelHue + (i * 65536L / strip.numPixels());
-      // strip.ColorHSV() can take 1 or 3 arguments: a hue (0 to 65535) or
-      // optionally add saturation and value (brightness) (each 0 to 255).
-      // Here we're using just the single-argument hue variant. The result
-      // is passed through strip.gamma32() to provide 'truer' colors
-      // before assigning to each pixel:
-      strip.setPixelColor(i, strip.gamma32(strip.ColorHSV(pixelHue)));
-    }
+    // strip.rainbow() can take a single argument (first pixel hue) or
+    // optionally a few extras: number of rainbow repetitions (default 1),
+    // saturation and value (brightness) (both 0-255, similar to the
+    // ColorHSV() function, default 255), and a true/false flag for whether
+    // to apply gamma correction to provide 'truer' colors (default true).
+    strip.rainbow(firstPixelHue);
+    // Above line is equivalent to:
+    // strip.rainbow(firstPixelHue, 1, 255, 255, true);
     strip.show(); // Update strip with new contents
     delay(wait);  // Pause for a moment
   }

library.properties

@@ -1,5 +1,5 @@
 name=Adafruit NeoPixel
-version=1.10.0
+version=1.10.1
 author=Adafruit
 maintainer=Adafruit <[email protected]>
 sentence=Arduino library for controlling single-wire-based LED pixels and strip.