Fixed block rendering issues

Fixed issues where graphic blocks had horizontal stripes in them

src/teletext/charsets.py

@@ -15,10 +15,10 @@ ENGLISH = {
 
 # Swedish/Finnish/Hungarian - Option 010 (2)
 SWEDISH_FINNISH = {
-    0x23: '#', 0x24: '¤', 0x40: 'É', 
-    0x5B: 'Ä', 0x5C: 'Ö', 0x5D: 'Å', 0x5E: 'Ü', 
-    0x5F: '_', 0x60: 'é', 
-    0x7B: 'ä', 0x7C: 'ö', 0x7D: 'å', 0x7E: 'ü'
+    0x23: '#', 0x24: '\u00A4', 0x40: '\u00C9', 
+    0x5B: '\u00C4', 0x5C: '\u00D6', 0x5D: '\u00C5', 0x5E: '\u00DC', 
+    0x5F: '_', 0x60: '\u00E9', 
+    0x7B: '\u00E4', 0x7C: '\u00F6', 0x7D: '\u00E5', 0x7E: '\u00FC'
 }
 
 # German - Option 001 (1) 
@@ -58,3 +58,22 @@ def get_char(byte_val, subset_idx):
         return mapping[valid_byte]
         
     return chr(valid_byte)
+
+import unicodedata
+
+def get_byte_from_char(char, subset_idx):
+    if len(char) != 1: return 0
+    
+    # Normalize input to NFC to match our map keys (if they are NFC, which python literals usually are)
+    char = unicodedata.normalize('NFC', char)
+    
+    if subset_idx < 0 or subset_idx >= len(SETS):
+        subset_idx = 0
+        
+    mapping = SETS[subset_idx]
+    
+    for code, mapped_char in mapping.items():
+        if mapped_char == char:
+            return code
+            
+    return ord(char)