start header doesn't need to be instance val

Author: mcscope

adafruit_dotstar.py

@@ -36,6 +36,8 @@
 __version__ = "0.0.0-auto.0"
 __repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_DotStar.git"
 
+START_HEADER_SIZE = 4
+
 # Pixel color order constants
 RGB = (0, 1, 2)
 RBG = (0, 2, 1)
@@ -89,19 +91,18 @@ def __init__(self, clock, data, n, *, brightness=1.0, auto_write=True, pixel_ord
             self.cpin.direction = digitalio.Direction.OUTPUT
             self.cpin.value = False
         self._n = n
-        self.start_header_size = 4
         # Supply one extra clock cycle for each two pixels in the strip.
         self.end_header_size = n // 16
         if n % 16 != 0:
             self.end_header_size += 1
-        self._buf = bytearray(n * 4 + self.start_header_size + self.end_header_size)
+        self._buf = bytearray(n * 4 + START_HEADER_SIZE + self.end_header_size)
         self.end_header_index = len(self._buf) - self.end_header_size
         self.pixel_order = pixel_order
         # Four empty bytes to start.
-        for i in range(self.start_header_size):
+        for i in range(START_HEADER_SIZE):
             self._buf[i] = 0x00
         # Mark the beginnings of each pixel.
-        for i in range(self.start_header_size, self.end_header_index, 4):
+        for i in range(START_HEADER_SIZE, self.end_header_index, 4):
             self._buf[i] = 0xff
         # 0xff bytes at the end.
         for i in range(self.end_header_index, len(self._buf)):
@@ -116,7 +117,7 @@ def __init__(self, clock, data, n, *, brightness=1.0, auto_write=True, pixel_ord
     def deinit(self):
         """Blank out the DotStars and release the resources."""
         self.auto_write = False
-        for i in range(self.start_header_size, self.end_header_index):
+        for i in range(START_HEADER_SIZE, self.end_header_index):
             if i % 4 != 0:
                 self._buf[i] = 0
         self.show()
@@ -136,7 +137,7 @@ def __repr__(self):
         return "[" + ", ".join([str(x) for x in self]) + "]"
 
     def _set_item(self, index, value):
-        offset = index * 4 + self.start_header_size
+        offset = index * 4 + START_HEADER_SIZE
         rgb = value
         if isinstance(value, int):
             rgb = (value >> 16, (value >> 8) & 0xff, value & 0xff)
@@ -171,14 +172,14 @@ def __getitem__(self, index):
             out = []
             for in_i in range(*index.indices(len(self._buf) // 4)):
                 out.append(
-                    tuple(self._buf[in_i * 4 + (3 - i) + self.start_header_size] for i in range(3)))
+                    tuple(self._buf[in_i * 4 + (3 - i) + START_HEADER_SIZE] for i in range(3)))
             return out
         if index < 0:
             index += len(self)
         if index >= self._n or index < 0:
             raise IndexError
         offset = index * 4
-        return tuple(self._buf[offset + (3 - i) + self.start_header_size]
+        return tuple(self._buf[offset + (3 - i) + START_HEADER_SIZE]
                      for i in range(3))
 
     def __len__(self):
@@ -224,9 +225,9 @@ def show(self):
         if self.brightness < 1.0:
             buf = bytearray(self._buf)
             # Four empty bytes to start.
-            for i in range(self.start_header_size):
+            for i in range(START_HEADER_SIZE):
                 buf[i] = 0x00
-            for i in range(self.start_header_size, self.end_header_index):
+            for i in range(START_HEADER_SIZE, self.end_header_index):
                 buf[i] = self._buf[i] if i % 4 == 0 else int(self._buf[i] * self._brightness)
             # Four 0xff bytes at the end.
             for i in range(self.end_header_index, len(buf)):