1  # The MIT License (MIT)
 2  #
 3  # Copyright (c) 2018 Scott Shawcroft for Adafruit Industries LLC
 4  #
 5  # Permission is hereby granted, free of charge, to any person obtaining a copy
 6  # of this software and associated documentation files (the "Software"), to deal
 7  # in the Software without restriction, including without limitation the rights
 8  # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 9  # copies of the Software, and to permit persons to whom the Software is
10  # furnished to do so, subject to the following conditions:
11  #
12  # The above copyright notice and this permission notice shall be included in
13  # all copies or substantial portions of the Software.
14  #
15  # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16  # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17  # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
18  # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19  # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20  # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
21  # THE SOFTWARE.
22  """
23  `adafruit_imageload.pnm.pbm_binary`
24  ====================================================
25  
26  Load pixel values (indices or colors) into a bitmap and for an ascii ppm,
27  return None for pallet.
28  
29  * Author(s):  Matt Land, Brooke Storm, Sam McGahan
30  
31  """
32  
33  __version__ = "0.0.0-auto.0"
34  __repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_ImageLoad.git"
35  
36  
37  def load(file, width, height, bitmap=None, palette=None):
38      """
39      Load a P4 'PBM' binary image into the displayio.Bitmap
40      """
41      x = 0
42      y = 0
43      while True:
44          next_byte = file.read(1)
45          if not next_byte:
46              break  # out of bits
47          for bit in iterbits(next_byte):
48              bitmap[x, y] = bit
49              x += 1
50              if x > width - 1:
51                  y += 1
52                  x = 0
53              if y > height - 1:
54                  break
55      return bitmap, palette
56  
57  
58  def iterbits(b):
59      """
60      generator to iterate over the bits in a byte (character)
61      """
62      in_char = reverse(int.from_bytes(b, "little"))
63      for i in range(8):
64          yield (in_char >> i) & 1
65  
66  
67  def reverse(b):
68      """
69      reverse bit order so the iterbits works
70      """
71      b = (b & 0xF0) >> 4 | (b & 0x0F) << 4
72      b = (b & 0xCC) >> 2 | (b & 0x33) << 2
73      b = (b & 0xAA) >> 1 | (b & 0x55) << 1
74      return b