1  #!/usr/bin/python3
 2  
 3  # Persistence-of-vision (POV) example for Adafruit DotStar RGB LED strip.
 4  # Loads image, displays column-at-a-time on LEDs at very high speed,
 5  # suitable for naked-eye illusions.
 6  # See dotstar_simpletest.py for a much simpler example script.
 7  # See dotstar_image_paint.py for a slightly simpler light painting example.
 8  # This code accesses some elements of the dotstar object directly rather
 9  # than through function calls or setters/getters...this is poor form as it
10  # could break easily with future library changes, but is the only way right
11  # now to do the POV as quickly as possible.
12  # May require installing separate libraries.
13  
14  import board
15  from PIL import Image
16  import adafruit_dotstar as dotstar
17  
18  NUMPIXELS = 30  # Length of DotStar strip
19  FILENAME = "hello.png"  # Image file to load
20  ORDER = dotstar.BGR  # Change to GBR for older DotStar strips
21  
22  # First two arguments in strip declaration identify the clock and data pins
23  # (here we're using the hardware SPI pins).
24  DOTS = dotstar.DotStar(
25      board.SCK,
26      board.MOSI,
27      NUMPIXELS,
28      auto_write=False,
29      brightness=1.0,
30      pixel_order=ORDER,
31  )
32  
33  # Load image in RGB format and get dimensions:
34  print("Loading...")
35  IMG = Image.open(FILENAME).convert("RGB")
36  PIXELS = IMG.load()
37  WIDTH = IMG.size[0]
38  HEIGHT = IMG.size[1]
39  print("%dx%d pixels" % IMG.size)
40  
41  if HEIGHT > NUMPIXELS:
42      HEIGHT = NUMPIXELS
43  
44  # Calculate gamma correction table, makes mid-range colors look 'right':
45  GAMMA = bytearray(256)
46  brightness = 0.25
47  for i in range(256):
48      GAMMA[i] = int(pow(float(i) / 255.0, 2.7) * brightness * 255.0 + 0.5)
49  
50  # Allocate list of lists, one for each column of image.
51  print("Allocating...")
52  COLUMN = [0 for x in range(WIDTH)]
53  for x in range(WIDTH):
54      COLUMN[x] = [[0, 0, 0, 0] for _ in range(HEIGHT)]
55  
56  # Convert entire RGB image into columnxrow 2D list.
57  print("Converting...")
58  for x in range(WIDTH):  # For each column of image
59      for y in range(HEIGHT):  # For each pixel in column
60          value = PIXELS[x, y]  # Read RGB pixel in image
61          COLUMN[x][y][0] = GAMMA[value[0]]  # Gamma-corrected R
62          COLUMN[x][y][1] = GAMMA[value[1]]  # Gamma-corrected G
63          COLUMN[x][y][2] = GAMMA[value[2]]  # Gamma-corrected B
64          COLUMN[x][y][3] = 1.0  # Brightness
65  
66  print("Displaying...")
67  while True:  # Loop forever
68  
69      for x in range(WIDTH):  # For each column of image...
70          DOTS[0 : DOTS.n] = COLUMN[x]  # Copy column to DotStar buffer
71          DOTS.show()  # Send data to strip