Added ColorEightByEight class and example program for Adafruit Bicolor LED Square Pixel Matrix with I2C Backpack

Added note about possible pixel indexing bug in the non-color version.  I don't have the non-color version to test with.

Added note about possible unintentional color "blending" bug in the Arduino color version.

Author: mprice

Adafruit_LEDBackpack/Adafruit_8x8.py

@@ -33,8 +33,8 @@ def setPixel(self, x, y, color=1):
     if (x >= 8):
       return
     if (y >= 8):
-      return
-    x += 7
+      return    
+    x += 7   # ATTN: This might be a bug?  On the color matrix, this causes x=0 to draw on the last line instead of the first.
     x %= 8
     # Set the appropriate pixel
     buffer = self.disp.getBuffer()
@@ -47,3 +47,29 @@ def clear(self):
     "Clears the entire display"
     self.disp.clear()
 
+class ColorEightByEight(EightByEight):
+  def setPixel(self, x, y, color=1):
+    "Sets a single pixel"
+    if (x >= 8):
+      return
+    if (y >= 8):
+      return
+
+    x %= 8
+
+    # Set the appropriate pixel
+    buffer = self.disp.getBuffer()
+
+    # TODO : Named color constants?
+    # ATNN : This code was mostly taken from the arduino code, but with the addition of clearing the other bit when setting red or green.
+    #        The arduino code does not do that, and might have the bug where if you draw red or green, then the other color, it actually draws yellow.
+    #        The bug doesn't show up in the examples because it's always clearing.
+
+    if (color == 1):
+      self.disp.setBufferRow(y, (buffer[y] | (1 << x)) & ~(1 << (x+8)) )
+    elif (color == 2):
+      self.disp.setBufferRow(y, (buffer[y] | 1 << (x+8)) & ~(1 << x) )
+    elif (color == 3):
+      self.disp.setBufferRow(y, buffer[y] | (1 << (x+8)) | (1 << x) )
+    else:
+      self.disp.setBufferRow(y, buffer[y] & ~(1 << x) & ~(1 << (x+8)) )

Adafruit_LEDBackpack/ex_8x8_color_pixels.py

@@ -17,15 +17,7 @@
 while(True):
   iter += 1
 
-  print (iter % 4)
-
   for x in range(0, 8):
     for y in range(0, 8):
-      grid.setPixel(x, y, iter%4 )
+      grid.setPixel(x, y, iter % 4 )
       time.sleep(0.02)
-
-# I think there is another bug here that drawing red or green after yellow doesn't clear the other component until you draw a blank
-
-#  time.sleep(0.5)
-#  grid.clear()
-#  time.sleep(0.5)