Set auto_write after brightness in init

This prevents an error from being thrown if the brightness is set to
something other than 1.0 and the pin for the led's is not yet set.

Author: dunkmann00

adafruit_pypixelbuf.py

@@ -61,6 +61,8 @@ def __init__(  # pylint: disable=too-many-locals,too-many-arguments
 
         bpp, byteorder_tuple, has_white, dotstar_mode = self.parse_byteorder(byteorder)
 
+        self.auto_write = False
+
         effective_bpp = 4 if dotstar_mode else bpp
         _bytes = effective_bpp * n
         buf = bytearray(_bytes)
@@ -89,8 +91,6 @@ def __init__(  # pylint: disable=too-many-locals,too-many-arguments
         self._dotstar_mode = dotstar_mode
         self._pixel_step = effective_bpp
 
-        self.auto_write = auto_write
-
         if dotstar_mode:
             self._byteorder_tuple = (
                 byteorder_tuple[0] + 1,
@@ -102,6 +102,8 @@ def __init__(  # pylint: disable=too-many-locals,too-many-arguments
         self._brightness = 1.0
         self.brightness = brightness
 
+        self.auto_write = auto_write
+
     @staticmethod
     def parse_byteorder(byteorder):
         """

examples/pypixelbuf_simpletest.py

@@ -12,7 +12,7 @@ def _transmit(self, buffer):  # pylint: disable=unused-argument
         self.called = True
 
 
-buf = TestBuf(20, "RGBW", 1.0, auto_write=True)
+buf = TestBuf(20, "RGBW", brightness=0.5, auto_write=True)
 buf[0] = (1, 2, 3)
 buf[1] = (1, 2, 3, 4)
 buf[2] = (2, 2, 2)