Fixed block rendering issues

Fixed issues where graphic blocks had horizontal stripes in them

src/teletext/renderer.py

@@ -4,7 +4,7 @@ from PyQt6.QtGui import QPainter, QColor, QFont, QImage, QBrush, QPen
 from PyQt6.QtCore import Qt, QRect, QSize, pyqtSignal
 
 from .models import Page, Packet
-from .charsets import get_char
+from .charsets import get_char, get_byte_from_char
 
 # Helper to create a blank packet
 def create_blank_packet(magazine: int, row: int) -> Packet:
@@ -168,7 +168,8 @@ class TeletextCanvas(QWidget):
                 
                 # Check if text is a single char
                 if len(text) == 1:
-                    byte_val = ord(text)
+                    byte_val = get_byte_from_char(text, self.subset_idx)
+                    
                     # Simple filter
                     if byte_val > 255: byte_val = 0x3F # ?
                     
@@ -188,7 +189,7 @@ class TeletextCanvas(QWidget):
                      # But for sanity, let's just append.
                      
                      # Write the char
-                     byte_val = ord(text)
+                     byte_val = get_byte_from_char(text, self.subset_idx)
                      if byte_val > 255: byte_val = 0x3F
                      new_packet.data[self.cursor_x] = byte_val
                      
@@ -365,7 +366,12 @@ class TeletextCanvas(QWidget):
         if val >= 0x20:
             bits = val - 0x20
             
-        blocks = [
+        # Grid definitions for 2x3 grid
+        x_splits = [0, int(self.cell_w / 2), self.cell_w]
+        y_splits = [0, int(self.cell_h / 3), int(2 * self.cell_h / 3), self.cell_h]
+        
+        # Block indices (col, row) for the 6 bits
+        block_indices = [
             (0, 0), (1, 0), # Top
             (0, 1), (1, 1), # Mid
             (0, 2), (1, 2)  # Bot
@@ -373,24 +379,26 @@ class TeletextCanvas(QWidget):
         
         bit_mask = [1, 2, 4, 8, 16, 64] # 64 is bit 6
         
-        bw = self.cell_w / 2
-        bh = self.cell_h / 3
-        
-        if not contiguous:
-            bw -= 1
-            bh -= 1
-        
         painter.setPen(Qt.PenStyle.NoPen)
         painter.setBrush(QBrush(color))
         
         for i in range(6):
             if bits & bit_mask[i]:
-                bx = x + blocks[i][0] * (self.cell_w / 2)
-                by = y + blocks[i][1] * (self.cell_h / 3)
+                c, r = block_indices[i]
+                
+                bx_local = x_splits[c]
+                by_local = y_splits[r]
+                bw = x_splits[c+1] - x_splits[c]
+                bh = y_splits[r+1] - y_splits[r]
+                
+                bx = x + bx_local
+                by = y + by_local
                 
                 if not contiguous:
                     bx += 1
                     by += 1
+                    bw -= 1
+                    bh -= 1
                     
                 painter.drawRect(QRect(int(bx), int(by), int(bw), int(bh)))