add length and brightness capabilities

Author: ladyada

neopixel.py

@@ -6,12 +6,13 @@
 
 class NeoPixel:
     ORDER = (1, 0, 2, 3)
-    def __init__(self, pin, n, bpp=3):
+    def __init__(self, pin, n, bpp=3, brightness=1.0):
         self.pin = digitalio.DigitalInOut(pin)
         self.n = n
         self.bpp = bpp
         self.buf = bytearray(n * bpp)
         self.pin.switch_to_output()
+        self.brightness = brightness
 
     def __enter__(self):
         return self
@@ -29,9 +30,20 @@ def __getitem__(self, index):
         return tuple(self.buf[offset + self.ORDER[i]]
                      for i in range(self.bpp))
 
+    def __len__(self):
+        return self.n
+
+    def set_brightness(self, range):
+        if (range > 1.0):
+            self.brightness = 1.0
+        elif (range < 0):
+            self.brightness = 0.0
+        else:
+            self.brightness = range
+
     def fill(self, color):
         for i in range(self.n):
             self[i] = color
 
     def write(self):
-        neopixel_write(self.pin, self.buf)
+        neopixel_write(self.pin, bytearray([int(i * self.brightness) for i in self.buf]))