From 0c51c74fd8cf8bc9b7cea6afe17d1a8430f43e86 Mon Sep 17 00:00:00 2001
From: "Adrian A. Baumann" <ade@adebaumann.com>
Date: Sun, 26 Oct 2025 18:15:32 +0000
Subject: [PATCH] Fix Scroll() buffer manipulation for mirrored display

---
 matrixclock/Display.py | 25 ++++++++-----------------
 1 file changed, 8 insertions(+), 17 deletions(-)

diff --git a/matrixclock/Display.py b/matrixclock/Display.py
index 6e99e08..2977ddf 100644
--- a/matrixclock/Display.py
+++ b/matrixclock/Display.py
@@ -92,7 +92,6 @@ class Display(object):
             if Immediate == True:
                 self.np.write()
         except KeyError:
-            #print("No such word")
             pass
             
     def WriteSentence(self,sentence,color=(25,25,0)):
@@ -102,50 +101,43 @@ class Display(object):
         self.np.write()
         
     def Scroll(self,Direction,Fill=[(0,0,0)]*16):
-        """Optimized scroll using direct buffer manipulation for all directions."""
+        """Optimized scroll for horizontally mirrored display (NeoPixel 0 at top-right)."""
         newbuf=bytearray(b'')
         
         if Direction == 'l':
-            # Optimized left scroll - existing implementation
             for Row in range(0,self.Rows,2):
                 newbuf += self.np.buf[Row*16*3+3:Row*16*3+48]
-                newbuf+=bytearray([Fill[Row][1],Fill[Row][0],Fill[Row][2]])
+                newbuf += bytearray([Fill[Row][1],Fill[Row][0],Fill[Row][2]])
                 newbuf += bytearray([Fill[Row+1][1],Fill[Row+1][0],Fill[Row+1][2]])
                 newbuf += self.np.buf[Row*16*3+48:Row*16*3+93]
             self.np.buf=newbuf
             
         elif Direction == 'r':
-            # Optimized right scroll using buffer manipulation
             for Row in range(0,self.Rows,2):
-                # Add fill pixels at the start
                 newbuf += bytearray([Fill[Row][1],Fill[Row][0],Fill[Row][2]])
-                newbuf += bytearray([Fill[Row+1][1],Fill[Row+1][0],Fill[Row+1][2]])
-                # Copy existing pixels (minus the last one from each row)
                 newbuf += self.np.buf[Row*16*3:Row*16*3+45]
-                newbuf += self.np.buf[Row*16*3+48:Row*16*3+93]
+                newbuf += self.np.buf[Row*16*3+51:Row*16*3+96]
+                newbuf += bytearray([Fill[Row+1][1],Fill[Row+1][0],Fill[Row+1][2]])
             self.np.buf=newbuf
             
         elif Direction == 'u':
-            # Optimized up scroll - skip first row, add fill at bottom
-            newbuf = self.np.buf[self.Columns*3:]  # Skip first row
+            newbuf = self.np.buf[self.Columns*3:]
             for Col in range(self.Columns):
                 color = Fill[Col]
                 newbuf += bytearray([color[1], color[0], color[2]])
             self.np.buf = newbuf
             
         elif Direction == 'd':
-            # Optimized down scroll - add fill at top, skip last row
             for Col in range(self.Columns):
                 color = Fill[Col]
                 newbuf += bytearray([color[1], color[0], color[2]])
-            newbuf += self.np.buf[:-self.Columns*3]  # Skip last row
+            newbuf += self.np.buf[:-self.Columns*3]
             self.np.buf = newbuf
             
         self.np.write()
      
     def ScrollLetter(self,Direction,Text,Speed,Color=[(50,50,50)],BGColor=[(0,0,0)]):
         """Optimized letter scrolling with pre-calculated columns."""
-        # Pre-calculate all columns for all letters
         all_columns = []
         for index,Letter in enumerate(Text):
             for X in range(3,14):
@@ -155,7 +147,6 @@ class Display(object):
                                        BGColor[index % len(BGColor)])
                 )
         
-        # Now scroll with pre-calculated data
         for column in all_columns:
             self.Scroll(Direction, column)
             sleep(Speed)
@@ -171,9 +162,9 @@ class Display(object):
         NeoPixel 0 is at top-right, serpentine wiring pattern."""
         Row=self.Num2Row(Pos)
         Col=self.Num2Column(Pos)
-        if Row%2 == 0:  # Even rows go right-to-left (mirrored from original)
+        if Row%2 == 0:
             NewPos=Row*self.Columns+(self.Columns-1-Col)
-        else:  # Odd rows go left-to-right
+        else:
             NewPos=Pos
         return NewPos