bugfix of mono bitshifter

Author: matt-land

adafruit_imageload/pnm/pbm_binary.py

@@ -44,7 +44,7 @@ def load(file, width, height, bitmap=None, palette=None):
         next_byte = file.read(1)
         if not next_byte:
             break  # out of bits
-        for bit in iterbits(int.from_bytes(next_byte, "little")):
+        for bit in iterbits(next_byte):
             bitmap[x, y] = bit
             x += 1
             if x > width - 1:
@@ -59,5 +59,16 @@ def iterbits(b):
     """
     generator to iterate over the bits in a byte (character)
     """
+    in_char = reverse(int.from_bytes(b, "little"))
     for i in range(8):
-        yield (b >> i) & 1
+        yield (in_char >> i) & 1
+
+
+def reverse(b):
+    """
+    reverse bit order so the iterbits works
+    """
+    b = (b & 0xF0) >> 4 | (b & 0x0F) << 4
+    b = (b & 0xCC) >> 2 | (b & 0x33) << 2
+    b = (b & 0xAA) >> 1 | (b & 0x55) << 1
+    return b

adafruit_imageload/tests/test_pbm_load.py

@@ -30,10 +30,11 @@
 from io import BytesIO
 from unittest import TestCase
 from .. import pnm
+from ..pnm.pbm_binary import iterbits, reverse
 from .displayio_shared_bindings import Bitmap_C_Interface, Palette_C_Interface
 
 
-class TestPnmLoad(TestCase):
+class TestPbmLoad(TestCase):
     def test_load_fails_with_no_header_data(self):
         file = BytesIO(b"some initial binary data: \x00\x01")
         try:
@@ -78,7 +79,7 @@ def test_load_works_p4_in_mem(self):
         self.assertEqual(4, bitmap.width)
         self.assertEqual(2, bitmap.height)
         bitmap.validate()
-        self.assertEqual("\n   1   0   1   0\n   1   0   1   0\n", str(bitmap))
+        self.assertEqual("\n   0   1   0   1\n   0   1   0   1\n", str(bitmap))
         palette.validate()
 
     def test_load_works_p4_binary(self):
@@ -123,3 +124,18 @@ def test_load_works_p4_binary_high_res(self):
         bitmap.validate()
         self.assertEqual(1, palette.num_colors)
         palette.validate()
+
+    def test_iterbits(self):
+        k = b'k'
+        bits = []
+        for byte in iterbits(k):
+            bits.append(byte)
+        #self.assertEqual([0,1,1,0,1,0,1,1], bits[::-1])
+        self.assertEqual([0,1,1,0,1,0,1,1], bits)
+
+    def test_reverse(self):
+        # 00110100 to 00101100
+        self.assertEqual(reverse(0x34), 0x2C)
+        self.assertEqual(reverse(0xFF), 0xFF)
+        self.assertEqual(reverse(0x00), 0x00)
+        self.assertEqual(reverse(0x0E), 0x70)